UNIDOS PTW -Universal Dosemeter

Transcription

1 PTW -Universal Dosemeter Firmware No and higher for type (connecting system M), S/N for type (connecting system W=TNC), S/N for type (connecting system N=BNT), S/N D /14 en Sa/Hn

2 - 2 - Disclaimer Disclaimer CE Mark The product bears the CE-mark "CE-0124" in accordance with the Council Directive 93/42/EEC about Medical Devices and fulfills the essential requirements of Annex 1 of this directive. The product is a class IIb device (MDD). CE-mark for officially calibrated dosemeters: The product bears the CE-mark "CE" in accordance with the Council Directive 89/336/EEC. General Information The instruction manual is an integral part of the device. It should always be kept near the device. Observance of the manual is a prerequisite for proper device performance and correct operation. Operator safety, specified measuring accuracy and interference-free operation can be guaranteed only if original devices and parts are used. Furthermore only the accessories listed in this manual are approved by PTW- Freiburg and may be used in conjunction with the device, or else accessories whose use has been expressly permitted by PTW-Freiburg. Safe operation and proper device performance are not guaranteed if accessories or consumables from other manufacturers are used. PTW-Freiburg cannot be held liable for damages resulting from the use of accessories or consumables from other manufacturers. The warranty period is 1 (one) year and begins on the day of delivery. It is unaffected by repairs covered by the warranty regulations. Devices on which moisture has developed as a result of temperature changes may not be switched on unless completely dry. PTW-Freiburg considers itself responsible for safety, reliability and performance of the device only, if assembly, extension, readjustment, modification or repair is carried out by PTW-Freiburg or by persons authorized by PTW-Freiburg, and if the device is used in compliance with the technical documentation. In case of any questions concerning service, support or warranty please contact your supplier. This technical documentation is in conformity with the device specifications and all applicable safety standards valid at printing date. All rights are reserved for devices, circuits, techniques and names appearing in the manual. No part of the technical documentation may be reproduced without written permission from PTW- Freiburg. The product fully complies with the electromagnetic immunity requirements of standard EN `Electromagnetic Compatibility - Medical Electrical Equipment`. The device is radio suppressed according to CISPR11/EN class B PTW-Freiburg is registered manufacturer according to the ElektroG (Elektro- und Elektronikgeräte-Gesetz). Elektro-Altgeräte-Register (EAR) Registration number DE PTW-Freiburg works in strict accordance with a quality management system which is continuously updated according to national and international standards. Safety instructions Dispose the packaging material according the applicable waste disposal regulations and keep it out of children's reach. Dispose used-up batteries according to national law. The product is a medical device. Only person with sufficient knowledge and skill may use the device. Before using the device, the operator must ascertain that it is in correct working order and operating condition. The operator must be trained in the use of the device. Set up the device so that the operator has a clear and unobstructed view of the control panel. The product is not suitable for operation in areas of risk where an explosion hazard may occur. Explosion hazards may be caused by the use of combustible anesthetics, skin-cleansing agents and disinfectants. Furthermore the device is of restricted suitability for application in oxygenenriched atmospheres. The atmosphere is considered to be oxygen enriched when more than 25 % of oxygen or nitrous oxide is added to the ambient air. Set up the device in a location which affords sufficient ventilation. The air gaps of the device must not be obstructed. Always observe the ambient conditions as indicated in the `Technical Specifications`. Peripheral devices (PC, printer) may only be connected if the devices meet the requirements of IEC The device is only for use to measure the dose within radiation field. The product must not be used to control radiodiagnostic equipment or radiotherapy units.

3 - 3 - Disclaimer The product is a device of IEC protection class 1. It may be put into operation only when connected to a properly installed power outlet with earthing contact. Before connecting the device to the power line, make sure that line voltage and frequency are equivalent to the ratings indicated on the nameplate of the device. Extension cords must not be used. All devices of a system must be connected to the same electric circuit. Devices not connected to that circuit must be electrically insulated (RS 232 interface with electrical insulation). Before putting the device into operation, visually inspect all connection cables for signs of damage. Damaged cables and connectors must be replaced immediately. When disconnecting the device from the power line, first remove the plug from the wall outlet, then disconnect the power cord from the device. Please observe the user manuals of all connected devices! Operation with patient contact The probes of the device may be operated with patient contact. The special instructions given in the instruction manual are to be observed. The product may not be operated within the patient environment (refer Figure 1). Together with the detectors mentioned in section the complies with the regulation DIN IEC 62C/130/CDV: It is classified according to VDE 0750 part 2-9. Figure 1: environment NOTE Definition of patient This symbol means: Refer to user manual. This symbol means: Device Type BF acc. IEC This symbol means: Separate collection for electrical and electronic equipment! (Refer also to section Disposal of the Product) This symbol means: The product bears the CE-mark.

4 - 4 - Disclaimer PTW-Freiburg Physikalisch-Technische Werkstätten Dr. Pychlau GmbH Lörracher Str Freiburg GERMANY Tel.: Fax: info@ptw.de

5 - 5 - Table of Contents Table of Contents 1 Introduction and Getting Started Introduction General Features Measuring Modes Measuring Ranges and Resolution Front Panel Ionization chambers Detectors for use with patient contact Getting Started General Hints Insert Rechargeable Batteries Putting into Operation Control Buttons Menu and Menu Keys Setting the Ionization Chamber A First Test Measurement In Case of Problems The Next Steps Basic Adjustments of General Hints Interval Time Language (German/English) Date and Time Measuring Units (radiological or electrical) RS232 Interface Parameters Entries to the Chamber Library Purpose of the Chamber Library Selecting the Chamber Library Showing Stored Chambers Editing Chamber Entries Adding Chamber Entries Deleting Chamber Entries Selecting Physical Quantities and Units Input of the Calibration Factor and the Check Reading General Hints Input of the Calibration Factor Input of the Check Reading Protecting Calibration Factors... 29

6 - 6 - Table of Contents 2 Preparing and Carrying out a Measurement Selecting a Chamber, the Measuring Quantity and the High Voltage General Hints Selecting a Chamber and a Measuring Quantity Setting the High Voltage Correction Factors General Hints Air Density Correction by Input of Temperature and Air Pressure Air Density Correction by Using the Radioactive Check Device Additional Correction Factors Performing a Measurement Preconditions Selection of Measuring Mode and Range Checking the Offset Current Performing a Measurement Reading the Measured Value Estimation of the Resolution Error Messages and Problems Error Messages on the Display Problems with Calibration and Correction Factors Verification of the Measured Value Problems with the Operation of The Measurement with Ionization Chambers Connection of Ionization Chambers to Air Density Correction General Input of Temperature and Air Pressure Adjusting the Reference Temperature of Using a Radioactive Check Device Correction Factors depending on Radiation Quality Testing the Offset Current Long-term Stability Chamber Voltage and Amplifier Polarity Effect Display... 55

7 - 7 - Table of Contents 4 Maintenance Drying Device NiCd or NiMH Rechargeable Battery Non-volatile RAM Repair of Calibrated Dosemeters Electrical Safety Change of the Mains Voltage Fuses Spare parts list Technical Data Dosemeter Circuit Diagrams Appendix: Potential Conditions Appendix: China Electronic Industry Standard Compliance Tables Table 1: Digital resolution and measuring ranges for current and charge measurement Table 2: Typical lower limits for a resolution of 0.5 % or better (dose and dose rate values are rounded off). The calibration factors represent typical values only Table 3: Typical values obtained by the system test after 15 s Pictures Figure 1: Definition of patient environment... 3 Figure 2: The front panel of with the socket for the signal input, LC-Display, control buttons, menu buttons and power button Figure 3: Mounting the rechargeable batteries Figure 4: Measuring window with measuring field, status and chamber line and on the right side the main menu Figure 5: Chamber menu Figure 6: Setup menu for adjusting the unit features and for performing test procedures Figure 7: Typical offset current versus time after switching on the at 23 C. The maximum value is about 300 fa immediately after switching the unit on. The warm-up period is 15 min Figure 8: Typical offset current versus time after switching on a warmed-up which has been switched off for 10 s. After switching on again the warm-up period should also be 15 min Figure 9: Positive and negative polarizing voltage... 74

8 - 8 - About this Manual About this Manual This instruction manual is an introduction to the operating of. It is assumed that the user has technical knowledge with respect to the handling and features of ionization chambers and other radiation detectors. Furthermore it is assumed that the user knows how to determine the dose from the uncorrected reading. The user has to know how to correct the reading depending on the radiation quality and energy to get the correct dose. For this reason detailed knowledge of the actual measurement protocol (e.g. ICRU report No. 35) is obligatory. NOTE The RS232 interface of is described in a separate manual.

9 - 9 - Introduction and Getting Started 1 Introduction and Getting Started 1.1 Introduction General Features - is a microprocessor-controlled universal reference-class dosemeter. It is used to measure dose and dose rate in radiotherapy, diagnostic radiology and radiation protection. As a dosemeter used in radiotherapy it fulfils the requirements of IEC standard 60731, as a dosemeter used in diagnostic radiology it fulfils the requirements of IEC standard 61674, and as a radiation protection dosemeter for stationary use it fulfils the requirements of IEC standard CAUTION Only ionization chambers or semi-conductor probes type BF (please refer to section 1.1.6) are allowed to be used together with with patient contact. Please obey the following rules: The must be placed outside the patient environment. To connect ionization chambers or semi-conductor probes an extension cable with protection cover must be used. If the detector is not connected to the the protective cover must be screwed onto the cable coupling of the extension cable to prevent from touching (please refer to chapter ordering information). The user should never touch the open cable coupling and the patient at the same time. - provides several measuring modes: Measurement of current and charge in electrical units (A, C). Measurement of radiological quantities as exposure JS in R, photon equivalent dose Hx in Sv, air kerma Ka and absorbed dose to water Dw in Gy. - can measure doses in radiation therapy up to 3 MGy as well as the dose of very short X-ray exposures in the range of ms. - shows the measuring time during dose measurements. - is prepared for measuring with ionization chambers, semi-conductor probes and other solid states probes (e.g. diamond detector).

10 Introduction and Getting Started - stores type and serial numbers for each detector in a non-volatile memory, together with the individual calibration factors and other factors specific for the chamber. - can store up to 30 ionization chambers or detectors respectively in the chamber library. - provides two modes of air density correction when measuring with ionization chambers: 1. Input of temperature and air pressure 2. Use of radioactive check device - Additional corrections can be taken into account by user-defined correction factor. Correction factors are stored for 30 min after the instrument is switched off. - The user cannot change calibration factors in the case of officially calibrated chambers. - provides an adjustable high voltage supply. High voltage is available in increments of 50 V up to the maximum of 400 V. Polarity can be reversed by a switch at the rear of the unit. - provides an indicator of the actual resolution. One or two blinking asterisks on the display indicate non-satisfactory resolution (for details see chapter 2.3.5). - operates with mains supply or with rechargeable batteries. With battery operation the duty cycle is approx. (7... 9) h. The display is switched off if the batteries are discharged. NOTE If the display is switched off please switch off the instrument to avoid an overdischarging of the batteries. This would shorten the lifetime of the batteries. - features a back-lit LC-Display, lit on mains operation. Brightness and contrast can be adjusted with a potentiometer on the front panel. - provides an RS232 interface for control by an external computer system. The computer system must meet the requirements of IEC The warm-up period is 15 min. - is available in three versions: a) With connecting system "M" (collecting electrode and guard are on earth potential) b) With connecting system "TNC" (collecting electrode and guard are on high voltage

11 Introduction and Getting Started as well as the pre-amplifier) c) With connecting system "BNT" (collecting electrode and guard are on high voltage as well as the pre-amplifier) CAUTION is a sensitive measuring device that needs regular testing and calibration. Please make sure that the following instructions are observed: 1. Perform regular checks of the device performance as described in chapter Make sure that is serviced and maintained in accordance with chapter Perform a complete re-calibration of the including the measuring probes at least every two years. 4. Do not subject the dosemeter to direct or stray radiation Measuring Modes The provides the two measuring modes "dose" and "dose rate". Furthermore two readings are accessible in the mode "dose rate": The dose rate and the dose calculated by numerical integration of the dose rate. The following items show the three different measuring possibilities. The differences in the measuring range and resolution are shown in Table 1 in chapter NOTE There are two methods of dose measurements available: 1. X-ray diagnostics: Use measuring mode "Dose", see a) below. 2. Radiotherapy: Use measuring mode "Dose Rate" and switch display to "Integrated Dose Rate", see c) below. a) Measuring mode "Dose": Dose and charge measurement by charge collection on a capacitor. Two capacitors are accessible for the measuring ranges Low and High. This mode is recommended if a very short measuring time is required. Examples for the application of this mode are dose measurements with diagnostic X-rays and radiation protection at X-ray exposures.

12 Introduction and Getting Started b) Measuring mode "Doserate", display of the dose rate: Dose rate and current measurements by measuring the voltage drop at a resistor. Three resistors are accessible for the measuring ranges Low, Medium and High. c) Measuring mode "Doserate", display of the Dose calculated by numerical integration: In the mode "dose rate" dose measurement is performed by numerical integration of the current. This kind of dose measurement is recommended for long time measurements. The maximum integration time is 18 h, the maximum measuring value is 3 MGy Measuring Ranges and Resolution digital resolution minimum maximum measuring mode: charge (dose) Low 10 fc (500 ngy) 2 pc (100µGy) 220 pc (10 mgy) High 500 fc (25 µgy) 100 pc (5 mgy) 22 nc (1 Gy) measuring mode: current (dose rate) Low 1 fa (3 µgy/min) 200 fa (600 µgy/min) 200 pa (0,5 Gy/min) Medium 50 fa (150 µgy/min) 10 pa (30 mgy/min) 10 na (28 Gy/min) High 5 pa (15 mgy/min) 1 na (3 Gy/min) 1 µa (2800 Gy/min) measuring mode: current (dose rate), display of integrated value: charge (dose) Low 10 fc (500 ngy) 2 pc (100 µgy) 12 µc (600 Gy) Medium 0,5 pc (25 µgy) 100 pc (5 mgy) 600 µc (30 kgy) High 50 pc (2,5 mgy) 10 nc (500 mgy) 65 mc (3 MGy) Table 1: Digital resolution and measuring ranges for current and charge measurement. The minimum value is determined by the resolution limit of 0.5 %. The dose and dose rate values are rounded values. They refer to a PTW ionization chamber with a volume of 0.6 cm 3, calibrated for absorbed dose to water. The offset current of without a detector connected is less than ± 1 fa. In the case of charge measurement the drift is less than ± 60 fc within the measuring time of 1 min.

13 Introduction and Getting Started Front Panel Figure 2: The front panel of with the socket for the signal input, LC-Display, control buttons, menu buttons and power button. Brightness and contrast can be adjusted with two potentiometers. The menu buttons ENT (Enter), ESC(Escape) and the arrow keys enable the selection of menu items of the display as well as the input of numerical values and characters Ionization chambers The standard chamber for the is the ionization chamber type PTW with a volume of 0.6 cm³. The present user manual refers to this chamber in general. In addition, a multiplicity of ionization chambers can be connected to the.

14 Introduction and Getting Started Detectors for use with patient contact For measurements with patient contact use only the ionization chambers and semi-conductor probes type BF which could be found in the following list. These detectors have the sign on the connector Type of detector Conn.-system TNC Conn.-system BNT Conn.-system M Micro chamber 0.1 cm 3 TW23323 TN23323 TM23323 C chamber 0.1 cm 3 TW23322 TN23322 TM23322 Semi-conductor probe TW9111 TN9111 TM9111 The ionization chambers or semi-conductor probes should only be used with the protective sleeves. For type and ordering number please refer to chapter ordering information.

15 Introduction and Getting Started 1.2 Getting Started General Hints In this chapter a functional test of the is performed. Furthermore the user is made familiar with. For this purpose it will be described how to carry out a first measurement without going into details such as correction factors Insert Rechargeable Batteries Due to their technology rechargeable batteries show a limited durability. In order to avoid the delivery of PTW devices with overaged batteries, brand-new NiCd or NiMH rechargeable batteries L are enclosed to the devices on delivery. Before setup these new rechargeable batteries have to be inserted into the device and have to be charged. - Remove the plate at the rear. - Now put in the rechargeable batteries. - Take care to keep the correct polarity, which is indicated on the stickers. The four upper batteries have to be put in with the positive side first whereas the lower four batteries with the negative side first. - Replace the plate with the four screws. - Perform an initial charging of the rechargeable batteries about 14 h. Then the PTW device will be ready for operation. Figure 3: Mounting the rechargeable batteries

16 Introduction and Getting Started CAUTION Equipment damage - Do not operate the with disposable batteries. Use only the special rechargeable NiCd or NiMH batteries. Equipment damage - If you do not operate the in battery operation for several month, remove the rechargeable NiCd or NiMH batteries. DANGER Explosion Hazard - Do not throw the rechargeable batteries into a fire. WARNING Bodily injury - If electrolyte leaks from the battery, avoid contact with skin or clothes. Immediately clean skin or clothes that have come in contact with electrolyte with water. In case of eye contact, immediately rinse eyes with water and consult doctor. Risk of Fire or Skin Burns - Never short the rechargeable batteries together. Equipment damage - Do not open rechargeable batteries. Never expose rechargeable batteries to water. Store and use the rechargeable batteries at the ambient conditions (temperature, relative humidity) specified for the device. Please refer also to the appropriate chapter of the user manual for information about the safe handling of rechargeable batteries. NOTE The rechargeable batteries will reach their full capacity only after several charging and discharging cycles. For information about the safe handling of rechargeable batteries refer to section 4.2.

17 Introduction and Getting Started Putting into Operation - Check the switch at the rear. Positive high voltage should be selected (HV polarity +). - Before connecting the unit to the mains check the adjusted voltage on the sticker at the rear (115 V / 230 V). The changing of the voltage is described in chapter Connect the unit to the mains, but do not connect the detector to the signal input. - The unit can be tilted by means of the carrying handle. The handle can be moved by pressing both locking knobs simultaneously. - Press the ON/OFF button to put the dosemeter into operation. The display shows the PTW logo for about 2 s as well as the version number of the firmware. Then the measuring window appears. measuring mode meas. range upper limit of meas. range chamber line main menu Figure 4: Measuring window with measuring field, status and chamber line and on the right side the main menu. The upper limit of the measuring range, given in radiological units, depends on the calibration factor of the adjusted chamber.

18 Introduction and Getting Started Control Buttons The main functions of are accessible with the seven control buttons: MOD, RGE, NUL, STA, HLD, RES and INT. These buttons are responsible for the following functions: MOD - RGE - displayed NUL - STA - HLD - RES - INT - Selection between the measuring modes "dose" and "doserate". The selected mode is indicated in the status field on the top left of the display. Selection of measuring ranges. In the measuring mode "dose" the ranges Low and High are available. In the measuring mode "dose rate" the ranges Low, Medium and High are available. The measuring range and the upper limit of the selected measuring quantity (dose, charge, dose rate or current) are in the status line on the right side. Automatic zeroing of the unit. The zeroing should be performed with the detector connected but not irradiated) and with the extension cable used for the measurements. The zeroing takes about 75 s. It can be interrupted by pressing the ESC button. In this case the electrical adjustment is not changed.*) Resets the reading to zero and starts a dose or charge measurement or a numerical integration. In the lower left corner of the measuring field "STA" is displayed. Above STA you can see the measuring time. Fixes a momentary dose or dose rate reading. The measurement however is not interrupted. The hold status is indicated in the measuring window by "HLD" in the lower left corner. To leave the hold status press the HLD key once again. Terminates dose measurements and resets the dose and time value to zero. It has no influence on the dose rate value. RES as well as ESC terminates the automatic zeroing. Performs STA and after the interval time HLD. The default value of the interval time is 60 s. See chapter for changing the interval time. *) If the message "zeroing not possible" appears press the ESC button and repeat the zeroing. The zeroing ist not possible during the first 5 min after switching on the.

19 Introduction and Getting Started Menu and Menu Keys After the is switched on the measurement window appears according to Figure 4. On the right of the measuring field the main menu appears with the following items: - SETUP - D &D or Q I (only in measuring mode "doserate" or "current") - CORRECT (only if radiological units are chosen) - CHAMBER The blinking cursor can be moved from item to item with the arrow keys on the right side of the display. After pressing ENT the window associated with the selected menu item appears. Pressing ESC quits the window and you are back in the main menu. The Setup and Correction menus will be described in detail in chapters 1.3 and 0. The menu item "CHAMBER" allows the setup of an ionization chamber, the high voltage, the measuring quantity and the calibration factors. This procedure will be described in the next chapter Setting the Ionization Chamber - Be sure that shows the measuring window according to Figure 4. If necessary, press the ESC key. - Use the arrow keys to move the cursor to the menu item "CHAMBER". Press ENT to get to the Chamber menu (see Figure 5). The cursor should now be positioned in the first line before the word "CHAMBER". relates each chamber to an entry number. This number appears on the right side of the word "CHAMBER". Additionally each chamber can be labeled. This label appears in the first line as well. - Now press ENT to set the cursor to the entry number. Use the arrow keys to toggle through the chamber library. If the entry number does not change only data for one chamber are stored in your. Figure 5: Chamber menu

20 Introduction and Getting Started - When the desired chamber appears press ENT. - Check if the indicated high voltage is suitable for the selected chamber. If you want to change the chamber voltage proceed as follows: Set the cursor with the arrow keys to the line "Voltage". Press ENT to set the cursor to the numerical value for the high voltage. Select the desired voltage with the arrow keys. Press ENT to set the actual high voltage to the selected value. - Check whether the calibration factor N is greater than 0. To change the calibration factor proceed as follows: Set the cursor to the line of the calibration factor N. Press ENT to move the cursor to the numerical value of the calibration factor. Select the desired value for each digit of the calibration factor with the arrow keys, then press ENT (the calibration factor for a chamber (0.6 cm 3 ) is about Gy/C). Pay attention to the positive sign of the exponent. Check after the procedure whether the calibration factor has been set to the correct value. - Press ESC to get back to the main menu.

21 Introduction and Getting Started A First Test Measurement - Check the following before you connect the ionization chamber to : The correct entry number and chamber label should be indicated in the chamber line (last line on the measuring window). Make sure that the correct value of high voltage is adjusted in the chamber menu. WARNING Use only ionization chambers which are adapted to the connecting system of (M, TNC or BNT system). Please note that adaption cables from one system to the other may result in high voltage on touchable parts of the connectors or of the ionization chamber. - Now connect the ionization chamber to the. It is not necessary to switch the off. - Select the desired measuring mode (dose or dose rate) with the MOD key. - If you want to perform a numerical dose integration (in the case of the measuring mode "dose rate") select D &D in the main menu. The status line shows " Doserate dt ". - Press the STA key to perform a zero measurement (the chamber is not irradiated). If necessary execute the automatic zeroing by pressing the NUL key. The zeroing takes about 75 s. *) - Now irradiate the ionization chamber and try the control keys STA, HLD, RES and INT. If you wish to perform a numerical dose integration move the cursor to the menu item "D &D". Press ENT to get the actual dose rate during the dose integration. *) If the message "adjustment impossible" appears, press the ESC key and repeat the zeroing. The zeroing is not possible during the first 5 min after switching on the.

22 Introduction and Getting Started In Case of Problems After switching on the LC-Display remains dark. Check the power cable. Set contrast and brightness of the display with the potentiometers on the front panel. The message "LowBat" appears blinking below the status line. Check the power cable and the connection to the mains. The measuring value remains zero even if the ionization chamber is irradiated. Check if the calibration factor is greater than 0 (see chapter 1.2.6). Use another ionization chamber or another extension cable. The automatic zeroing is impossible. Wait at least 5 min after switching on. This is also necessary, if has been switched off only for a short time. Before a zeroing, that should possess validity for longer time, the warm-up period of 15 min is to be waited, see chapter 4. Be sure the chamber is not irradiated during the zeroing. Connect the chamber to without the extension cable. If the zeroing works now the extension cable is defective. Disconnect the chamber and the extension cable from. If now the zeroing works the ionization chamber is defect or the humidity in the chamber or in the connector is too high (if humidity is too high, leakage currents in the ionization chamber may occur, see chapter 3).

23 Introduction and Getting Started The Next Steps You are now quite familiar with the basic functions of your. It is now time to tell which ionization chambers or detectors you want to use. Afterwards you will be able to execute correct dose and dose rate measurements. The next steps are as follows: - Basic adjustment of (chapter 1.3). - Entries to the chamber library (chapter 1.4). - Input of the calibration factors and the check readings (chapter 1.5). - Carrying out a correct measurement (chapter 2). 1.3 Basic Adjustments of General Hints The allows to some features with the help of the Setup menu. The adjustments are stored in a non-volatile memory (see chapter 4.3). Furthermore the setup menu provides test procedures such as the display test (see 3.4.5) or the chamber voltage test (see 3.4.3). The Setup menu is called by selecting the menu item "SETUP" in the main menu. Move the cursor to the setup line and press ENT. Then the following menu appears. Figure 6: Setup menu for adjusting the unit features and for performing test procedures. With the arrow keys the desired menu item can be selected. Press ENT to activate the item. You can cancel amendments by pressing ESC.

24 Introduction and Getting Started Interval Time The interval time is used with the control key INT. If a dose or charge measurement is started with INT the changes to hold status after the interval time. The interval time affects also the measuring time to determine the control reading k m (see chapter 2.2.3). The interval time should not be less than 60 s for this measurement. The standard value for the interval time is 60 s. The available range is 6 s to 9999 s. NOTE The interval time is quickly adjusted to 6 s or 60 s by using the keys NUL or RES instead of the arrow keys Language (German/English) - Select in the setup menu the item "Miscellaneous". Select the item "Language" by pressing ENT. - Choose the language with the arrow keys. Finally quit by ENT. Press ESC to leave the menu Date and Time - Select the menu item "Miscellaneous". Move to line "Date" or "Time". - Adjust the date or time with the arrow keys. Quit each input with ENT till the cursor moves to the front of the line. Press ESC to leave the menu "Miscellaneous".

25 Introduction and Getting Started Measuring Units (radiological or electrical) - Select the menu item "Units". Select the desired unit with the arrow key. Quit with ENT. NOTE provides several radiological units (Gy, Sv). To select a specific radiological unit see chapter RS232 Interface Parameters - Move the cursor to the line "RS232 Parameters". - Select the desired parameter by pressing ENT once or twice. Adjust the parameters with the arrow keys. - Press ENT till the cursor is on the beginning of the line. 1.4 Entries to the Chamber Library Purpose of the Chamber Library Before any dose or dose rate measurement must be adjusted to a specific ionization chamber. The entry number and the label of the ionization chamber are shown in the chamber line (last line of the measuring window). checks automatically for which quantity the chamber is calibrated. Furthermore provides the calibration factor and sets the high voltage to the last value used with that chamber. Before using the you should enter all chambers that you are using in the chamber library. The necessary steps are described in the following Selecting the Chamber Library - Select "SETUP" in the main menu. - Select "Chamber Library" in the setup menu. You can quit the chamber library with ESC.

26 Introduction and Getting Started Showing Stored Chambers - Select the menu item "Show/Edit Entries". - Select the chamber type and change the type number with the arrow keys. In the second line, it is shown whether a chamber entry exists to the momentary shown type number. Select the type number "*" if you want to use a chamber with a type number not stored in. This type stands for any chamber type which is not administered by. - If the type number has got an entry press ENT and select the menu item "Entry Number". With the arrow keys you can toggle through the different chamber entries belonging to this type number. Quit the item with ESC Editing Chamber Entries - Select the menu item "Show/Edit Entries". - Select the chamber corresponding to chapter Select the menu item "Edit Entry". - Select the desired line with the arrow keys, press ENT and change the values using the arrow keys. Quit with ENT or cancel with ESC. CAUTION The serial number of a chamber with protected calibration factor is not erasable. Only entry numbers of chambers which are not listed in the chamber library can be chosen. The label for the ionization chamber has to be entered digit by digit and character by character. In this mode the following control keys have special functions: NUL: 0 STA: A INT: a RES: space HLD: restoring of the character entered before

27 Introduction and Getting Started Adding Chamber Entries - Select the menu item "Add Entry". - Select the chamber type. If the desired type is not stored in use the "*" type. Select "diode" for solid state detectors. - Select the entry number. - Enter the serial number of the chamber. Enter the label. - Select the item "Add Entry" and press ENT to store the entry permanently Deleting Chamber Entries - Select the menu item "Delete Entry". - Select the desired chamber type. Select the entry number. - Move the cursor to the last line and press STA. NOTE 1.) Entries of chambers with protected calibration factors are not erasable. 2.) The actual selected chamber shown in the measuring window is not erasable. First select another chamber in the chamber menu (see 1.2.5) Selecting Physical Quantities and Units - Select the desired chamber as described in chapter Go back to the chamber library with ESC. - Select the item "Define Measuring Quantities & Units". - Select the desired quantities and adjust the unit for the dose rate measurement. Should an ionization chamber not be used for a specific unit choose OFF. - Go back with ESC into the menu "Chamber Library".

28 Introduction and Getting Started NOTE 1.) For each selected quantity a calibration factor has to be entered (see chapter 1.5.2). 2.) The quantity used in the measuring window cannot be switched off. First select another quantity. 1.5 Input of the Calibration Factor and the Check Reading General Hints The calibration factors of the ionization chambers delivered with are already stored in the memory. If you want to add chamber entries (according to chapter 1.4) the calibration factors have to be typed in for each measuring quantity. If you want to use a radioactive check device for a specific ionization chamber you have to enter the control reading, the radionuclide and its measuring date. This information is also permanently stored in. The calibration factor and the check reading can be taken from the test certificate of the chamber. NOTE We recommend to have the calibrated in time intervals of two years maximum by a qualified laboratory Input of the Calibration Factor - Select the measuring window and choose the menu item "CHAMBER". - Choose the desired ionization chamber. Move to the line "Calibration factor" and enter the calibration factor for the selected chamber. Check that the exponent has positive sign. Typical values of calibration factors for different ionization chambers are listed in table Table 2, chapter

29 Introduction and Getting Started WARNING Under no circumstances switch off the immediately after the input of a calibration factor! needs about 1 s to store the calibration factor internally. Switching off the during the storing procedure can cause a damage of the NOVRAM. Then all calibration data will be lost Input of the Check Reading If you want to use a radioactive check device, enter the check reading as follows: - Select the menu item "Chamber" in the measuring window. Choose the desired ionization chamber. - Move to the line "Source". Set the radionuclide and the date the control reading kp,0 refers to (see test certificate of the ionization chamber). - Move to the line kp,0 and set the value for the reference conditions (20 C or 22 C and hpa; see chapter and test certificate of the ionization chamber). NOTE To set the calibration factors for further measuring quantities, move to the line "Quantity" and choose the desired quantity. Now proceed as described above to set the calibration factor and eventually the check source and the check reading k p, Protecting Calibration Factors It is possible to protect the calibration factors against unauthorized change. This status is indicated in the chamber menu by the label *calibr.* The protecting procedure is as follows: - Disconnect from the mains. Switch off the. - Remove the front panel screws and carefully remove the panel. Pay attention not to disconnect any cable. - On the second printed circuit board from the left you can find a 4-pole DIL switch on the front end. This switch is accessible without removing the printed circuit board. With the first switch from above can be set in the protected calibration mode.

30 Introduction and Getting Started First switch from above to the left: protected calibration: OFF First switch from above to the right: protected calibration: ON - If the calibration mode is ON, calibration factors can be locked and unlocked. - If the calibration mode is OFF, neither the locking nor the unlocking of calibration factors is possible. - After the selection fix the front panel with the screws. Be sure that no cable gets jammed. If you now set the into operation you can lock or unlock calibration factors as follows: Locking: Enter the calibration factor as described in chapter Move the cursor to the line "Quantity" with the arrow keys. Press ENT to move the cursor to the quantity (for example Dw). - Press STA to lock the calibration factor. On the right side of the quantity the label *calibr.* appears. Unlocking: Protected calibration factors are labeled *calibr.* in the chamber menu. To unlock these calibration factors proceed as follows: - Move into the chamber menu as described in chapter Move the cursor to the line "Quantity" with the arrow keys. Press ENT to move the cursor to the quantity (for example Dw). - Press the RES key to unlock the calibration factor. - The calibration factor can now be changed as described in chapter After locking or unlocking the calibration factor do not forget to set the protected calibration mode OFF. For this purpose proceed as described in the beginning of this chapter and move the DIL switch back in the position: "protected calibration mode: OFF".

31 Preparing and Carrying out a Measurement 2 Preparing and Carrying out a Measurement 2.1 Selecting a Chamber, the Measuring Quantity and the High Voltage General Hints It is recommended to switch on without any detector connected. This procedure avoids that inadvertently too high voltage is applied to the detector. The warm-up period of is 15 min for stabilizing the offset current. Figure 7 (chapter 5) shows the offset current versus time after switching on. NOTE If is switched off for a short time the warm-up period of 15 min has also to be observed, even if has already reached its working temperature (see chapter 5, Figure 7). Usually there is no reason to switch off for a short time because: The power cable can be disconnected even while is switched on. The built-in accumulator takes over the power supply without any delay. In the case of troubles with the processor can be reset with the Resetbutton on the rear. Before a measurement you must tell which ionization chamber is to be used. Select the ionization chamber with the menu item "Chamber" on the right side of the measuring window. The selected ionization chamber is specified by the entry number and the label. This information is indicated in the bottom line of the display. Together with the ionization chamber selection, the measuring quantity and the high voltage are set. It is recommended not to connect the ionization chamber to before the chamber is selected and the adjusted high voltage is checked. In the following, it is assumed that the ionization chambers were properly inputed into the chamber library in accordance with section 1.4, and the calibration factors were inputed for the intended measuring quantities in accordance with section

32 Preparing and Carrying out a Measurement Selecting a Chamber and a Measuring Quantity - Choose the item "Chamber" in the main menu. - Press ENT and select the desired ionization chamber with the arrow keys. Press ENT to quit the selection. The cursor moves to the beginning of the line. - Select the desired measuring quantity and unit with the item "Quantity" (the measuring quantities and units accessible are filed in the chamber library, see chapter 1.4.7) Setting the High Voltage - Check the high voltage displayed in the chamber menu and the position of the slider "HV-polarity" on the rear. The default high voltage setting corresponds to the high voltage used last for the adjusted chamber. An ionization chamber normally is used with the highest allowed chamber voltage Umax. This voltage can be found in the according chamber data sheet. has stored Umax for each type of chamber; for the chamber type "*" you have Umax = 400V. It is not recommended to use an ionization chamber with a voltage less than 30 % of Umax. In this case a warning appears. If a chamber with protected calibration factors is used, the indication (*calibr.*) disappears from the measuring window. NOTE 1.) Check the high voltage before connecting any detector or ionization chamber to. 2.) The usual polarity of the collected charge is "+". (See also Appendix. The position of the HV switch corresponds to the potential of the chamber wall towards the central electrode.) Before changing the polarity with the switch "HV-Polarity" on the rear, select the measuring range High (with RGE) and make sure that no ionization chamber is connected to the. 3.) If the input current is negative, the minus sign appears on the left of the measuring value. - Press ESC to get back to the main menu. On the last line of the display the selected chamber is displayed.

33 Preparing and Carrying out a Measurement - Connect the ionization chamber to (it is not necessary to switch off). Pay attention to the correct type and serial number! NOTE is a very sensitive measuring instrument for the measurement of very low doses and dose rates. For the measuring range "Low" it is recommended to wait about 15 min after applying the high voltage to the ionization chamber. During this period the electric potential in the chamber will stabilize. 2.2 Correction Factors General Hints Correction factors are factors by which the measured value has to be multiplied to get the corrected value. indicates in the measuring field whether the reading is corrected or uncorrected. NOTE Correction factors are stored for approximately 30 min after switching off. There are no corrections possible for the detector type "diode" and "diamond". There are basically two correction factors: Air density correction kd either calculated from temperature and pressure or determined by a check measurement with a radioactive check device. The product k of all remaining correction factors (energy dependence of the ionization chamber, polarity effect or insufficient saturation, etc.)

34 Preparing and Carrying out a Measurement Air Density Correction by Input of Temperature and Air Pressure - Select the item "CORRECT" in the main menu. If necessary, select the correction mode "t&p" (press ENT on line "Air Density Correction" and toggle with the arrow keys). - Input the temperature in Centigrade (range of 10 C to 40 C is accepted). Input the absolute air pressure (range of 500 hpa to 1300 hpa is accepted). Note that the absolute air pressure is not the pressure corrected to sea level. The correction factor k is explained in chapter NOTE The correction factor k D calculated from temperature and pressure is indicated in the correction menu Air Density Correction by Using the Radioactive Check Device - Switch on and allow for a warm-up period of 15 min. Make sure that the temperature of the check device is equal to the temperature of the measuring point. - Check if the interval time matches the measuring time for kp,0 indicated in the test certificate for the ionization chamber (see chapter 1.3.2). - Set the measuring mode and range according to the test certificate of the ionization chamber. Perform an interval measurement with the ionization chamber not irradiated (key INT). The measured value should be less than 0.5 % of the check reading kp,0 indicated in the test certificate. - If necessary perform the automatic zeroing (NUL) with the ionization chamber not irradiated. - Select the menu item "CORRECT" in the main menu. If necessary select the correction mode "k p /k m" with the menu item "Air Density Correction". - Insert the ionization chamber into the radioactive check device. Take care that the serial number of the chamber, check device and of the adaptor itself correspond to the serial number indicated in the test certificate of the ionization chamber.

35 Preparing and Carrying out a Measurement - Check if the actual date is correctly displayed next to the k p value. calculates k p for the actual date, taking the radioactive decay into account. If the actual date is not displayed next to the k p value, switch the correction mode OFF and select "Correction mode k p /k m " again. - Select the menu item "measure k m " to start the k m measurement. The measuring time should correspond to the time indicated in the test certificate for the chamber (the measuring time is the interval time adjusted in the main menu). NOTE The k m measurement is not equivalent to an interval measurement. Performing a k m measurement only takes the calibration factor into account but not the correction factors k, k D and k p /k m. If you change the calibration factor of a chamber you also have to change the k p, 0 value to get correct measuring values with the k p /k m correction. k p, 0 is calculated according to Nnew k p,0,new = k p,0,old N old Additional Correction Factors - Select "CORRECT" in the main menu. - Set the desired air density correction (see chapter or 2.2.3). - Move to the last line "k" and input the correction factor k. The accepted input range is 0.5 to 2.0, usually k is in the range 0.8 to 1.2. NOTE The correction factor k is the product of all correction factors except the air density correction. The most important corrections are factors for correcting for the energy dependence of the ionization chamber as well as factor for the polarity effect and incomplete saturation. For details see the relevant dosimetry protocol (i.e. ICRU Report 35). The usual input range for k is 0.8 k 1.2. When entering values outside this range a warning message will appear.

36 Preparing and Carrying out a Measurement 2.3 Performing a Measurement Preconditions Check before starting a measurement: Wait at least 15 min after switching on the. This warm-up period must also be observed if is switched off for only a short time (see chapter 2.1.1). The correct ionization chamber is selected according to chapter 2.1. Before connecting the ionization chamber the correct high voltage has to be adjusted. The desired measuring quantity, unit and high voltage is adjusted (see chapter 2.1.) Correction factors are adjusted (see chapter 2.2). shows the measuring window with the main menu Selection of Measuring Mode and Range The measuring mode depends on the application. - Adjustment for dose measurements in radiation therapy: Select the mode "Doserate" with the MOD key. On the status line "Doserate" or " Doserate dt " is indicated. Select the menu item "D &D" with the arrow keys until " Doserate dt on the status line. " appears Select the desired measuring range with RGE (usually High). - Adjustment for dose measurements in X-ray diagnostics: Select the measuring mode "Dose" with MOD. On the status line "Dose" is indicated. Select the desired measuring range with RGE (usually Low). - Adjustment for dose rate measurements: Select the measuring mode "Doserate" with MOD. Now "Doserate" or " Doserate dt " is indicated on the status line.

37 Preparing and Carrying out a Measurement When " Doserate dt "Doserate" reading. " is indicated, switch with the menu item "D & D" to the Select the measuring range with RGE (as a rule High for radiation therapy and Low for X-ray diagnostics) Checking the Offset Current Check the reading of the dosemeter with the ionization chamber not irradiated as follows: - For dose measurements: Press the INT key to perform a measurement for the interval time. - For dose rate measurements: Observe the reading. - Compare the values expected with your measurements. If necessary perform the "automatic zeroing" (NUL). For the automatic zeroing the ionization chamber should be connected to with the extension cable used for the measurement. Do not move neither the ionization chamber nor the cable. An automatic zeroing takes about 75 s. - Check again the offset current after performing the zeroing. - Check the offset current without cable and ionization chamber when the offset current exceeds the usual value even if the warm-up period has been at least 15 min and the zeroing has been performed correctly. Please refer also to chapter Performing a Measurement - For dose measurements: start the measurement with STA or the INT key. "STA" is indicated on the bottom left of the measuring window. - For dose rate measurements: the dosemeter is automatically set to the "RUN" status. This means that the dosemeter is always prepared for a measurement. - With the HLD key the actual measuring value is fixed without interrupting the measure- ment. To finish the HLD status press the HLD key a second time. - In the case of dose measurement by numerical integration the reading can be changed from dose to dose rate with the menu item "D &D". - The reading can be reset with the RES key only for dose measurements.

38 Preparing and Carrying out a Measurement Reading the Measured Value "OL" (Overload) is indicated if the measuring range is overranged. The minus sign indicates negative current. This is the case if operates with negative high voltage or the measuring value is so low that the reading oscillates around zero. The polarity of the high voltage is selected with the switch on the rear. Before changing the polarity select the measuring range "high" and disconnect the ionization chamber from. Notice the prefix of the measuring unit. Unit and prefix are displayed on the right of the measured value. If one or two blinking "*" appear on the right top side of the measuring window the resolution is below a certain value. a) Blinking "**": The measuring value is based on a current or charge measurement with resolution worse than 1 %. In other words the reading in electrical units is less than 100 times the resolution. For X-ray diagnostics it is recommended that the resolution is at least 1 %. To improve the resolution select the lower measuring range with RGE. In the case of dose measuring in the mode "Dose" you can improve the resolution by extending the measuring time. You will find more details about this in the next chapter. b) Blinking "*": The displayed measuring value is based on a current or charge measurement with a resolution worse than 0.5 %. That means the reading in electrical units (A, C) is less than 200 times the resolution but over 100 times. For radiation therapy the resolution should be at least 0.5 %. To improve the resolution select the lower measuring range with RGE. In the case of dose measuring in the mode "Dose" you can improve the resolution by extending the measuring time. You will find more details in the next chapter. c) No blinking asterisks: The measuring value has a resolution of 0.5 % or better, sufficient for X-ray diagnostics and radiation therapy.

39 Preparing and Carrying out a Measurement Estimation of the Resolution As described in chapter the blinking "**" or "*" indicates a resolution which is less than 1 % or 0.5 %, respectively. Note, as the calculation of the resolution is based on a current or charge measurement it is possible that the dose or dose rate reading apparently shows a better resolution. Example: The 0.6 cm 3 ionization chamber has a calibration factor of about Gy/C. The ionization chamber irradiated may produce a current of pa. The reading in radiological units is therefore mgy/min. As a current resolution in the range Low is pa the current of 200 pa is measured with a resolution of 0.5 %. Therefore no blinking * is displayed. Now the dose rate is lowered so that the current falls to say 180 pa. The blinking "*" occurs as the resolution is now lower than 0.5 %, the corresponding resolution of the dose rate value of Gy/min is therefore less than 0.5 %, too. The display of the dose rate in radiological units (e.g mgy/min) must therefore not lead into the assumption, the resolution of the measurement is far better than 0,5%. Look at Table 1 (chapter 1.1.3) to get the lower limit for a measuring current or charge with a resolution of at least 0.5 %. The lower limits for measuring in radiological units, with the resolution better than 0.5 %, depend on the calibration factor of the ionization chamber. Table 2 shows the limits for different chamber volumes.

40 Preparing and Carrying out a Measurement Chamber Volume Calibration Factor [Gy/C] Mode "Dose" Lower Limits Mode "Doserate" Low High Low Medium High [Gy] [Gy] [Gy/min] [Gy/min] [Gy/min] 0.02 cm³ m m m cm³ m m 6.00 m cm³ m m 3.00 m m cm³ µ m m 30.0 m cm³ µ m m m cm³ µ µ µ m 60.0 m 112 cm³ µ µ 3.00 µ µ m 1000 cm³ n µ µ µ m cm³ n n n µ µ Table 2: Typical lower limits for a resolution of 0.5 % or better (dose and dose rate values are rounded off). The calibration factors represent typical values only. When measuring dose or charge by the numerical integration of dose rate or current respectively the reading may show an apparent resolution better than 1 % while the "*" or "**" are still blinking. In this case the resolution of the basic current measurement is less than 1 % or 0.5 %, respectively. Change to a lower measuring range to increase the resolution.

41 Preparing and Carrying out a Measurement 2.4 Error Messages and Problems Error Messages on the Display Below the status line "LowBat" is displayed blinking. The batteries are almost discharged. Nevertheless will operate with its full performance for about 20 min. After this time the display goes dark, the must be connected to the mains. Connect to the mains and switch on. The batteries will be recharged within 14 h. is protected against overloading. Blinking "*" or "**" on the right of the measuring value. The resolution for the basic current measurement is less than 0.5 % ("*" is blinking) or 1.0 % ("**" blinking). Extend the measuring time (only if measuring dose in the dose mode) or switch to a lower measuring range. Typical values for a lower limit obtaining a resolution of at least 0.5 % are listed in Table 2 (see chapter 2.3.6). "OL" instead of the measuring value. measuring OL means overload of the measuring range. OL may also appear if measuring the dose by numerical integration in the mode "Doserate" and the selected range for the basic dose rate measurement is overloaded. The message OL will disappear by pressing RES or selecting a higher range. In the mode " Doserate dt Clear OL by pressing RES. " the maximum integration time of 18 h is reached.

42 Preparing and Carrying out a Measurement After pressing the NUL key the message "zeroing impossible" appears. The detector has been moved or irradiated during the zeroing. The warm-up period after switching on was less than 5 min. This warm-up period must also be observed if has been switched off for a short time. Detector or extension cable are defective. Try zeroing without cable or detector. has been exposed to high humidity and the drying device is used up. Change the drying device (see chapter 4.1). Below the status line "HV Error" is blinking. The current limitation in the high voltage supply has been activated. Correct measurements are no longer possible. The cause of the problem may be a short circuit in the ionization chamber or in the extension cable. The 20 ma fuse labeled "HV Fuse" at the rear is blown. Correct measurements are no longer possible. The high voltage control circuit is defective. Correct measurements are no longer possible, must be sent to the factory for repair. The end value of the measuring range displayed in the uppermost line is blinking. The radiological calibration factor is 0.0. Enter the correct value (this error message is displayed only for firmware version 2.30 or higher).

43 Preparing and Carrying out a Measurement Problems with Calibration and Correction Factors Correction Factors: kp /k m out of The warning appears after measuring k m (see chapter 2.2.3). The correction factor k p /k m for the air density correction is out of The measuring value k m deviates from the control value k p by more than 20 %. The user can decide, whether the value will be stored or not. k out of The warning appears after input of the correction factor k (see chapter 2.2.4). The correction factor k is out of the usual range of The user can decide, whether the value will be stored or not. t out of 10 C C The error message appears after input of t for the air density correction. The error message will disappear after a short time. The input value is not accepted. p out of 500 hpa hpa The error message appears after input of p for the air density correction (see chapter 2.2.2). The error message will disappear after a short time. The input value is not accepted. k out of The error message appears after input of the correction factor k (see chapter 2.2.4). The error message will disappear after a short time. The input value is not accepted. resolution too small The error message appears after measuring km with radioactive check device (see chapter 2.2.3). Check that the measuring mode (MOD key) and the measuring range (RGE key) is set according to the test certificate.

44 Preparing and Carrying out a Measurement kp /k m out of The error message appears after measuring k m with the radioactive check device (see chapter 2.2.3). Compare the serial number of the - radioactive check device - ionization chamber - adaptor for the ionization chamber (only in the case of flexible chambers) with the corresponding values in the test certificate. Check the selected radionuclide and the actual date indicated in the chamber menu. Compare all the parameters in the chamber menu with the corresponding values in the test certificate. kp-date is obsolate The error message appears after selecting the k p /k m -correction menu if the has not been switched off over night (date has changed). The calculation of the kp-value is based on an older date. The message appears for about 2 s if the menu item "measure km" or "km" is selected. If km is correctly measured afterwards or entered manually, will calculate the proper kp-value for the actual date and also update the date and the ratio kp/km Calibration Factors: N out of The error message appears after input of the calibration factor N. The calibration factors deviates by a large amount from the typical values of the 0.02 cm³ ionization chamber resp. of the 10,000 cm³ chamber. Table 2 (chapter 2.3.6) shows typical calibration factors depending on the chamber volume. Pay attention to the positive sign of the exponent. The error messages will disappear after a short time. The input value is not accepted.

45 Preparing and Carrying out a Measurement Verification of the Measured Value In the case of a chamber with protected calibration factors the indication *calibr.* is not present. The high voltage is adjusted to a value less than 30 % of the maximum allowed voltage U max (see chapter 2.1.3). The measuring value remains zero. Check that the calibration factor for the selected ionization chamber is correctly adjusted. The measuring value is negative. po- The ionization current is negative. The polarity of the current depends on the larity of the high voltage. You have the impression that measuring value is not correct or inaccurate. Check the type and serial number of the ionization chamber connected and compare these to the corresponding values stored in. Check whether blinking "*" or "**" appear on the right of the measuring value. This indicates insufficient resolution of the measuring value (see chapter 2.3.5). Check the high voltage value displayed in the chamber menu. Check the selected measuring quantity, unit and calibration factor and compare these to the corresponding values in the test certificate. Check the correction factors kd, kp/km and k. Check the offset with the chamber not irradiated. If necessary perform the automatic zeroing (NUL) as described in Check the high voltage applied to the ionization chamber (see chapter 3.4.3).

46 Preparing and Carrying out a Measurement Problems with the Operation of The STA, RES and INT-key do not work in the measuring mode "dose rate" (resp. current). The STA, RES and INT-key are only activated for dose (or charge) measurements. For measuring dose in the measuring mode "dose rate" switch over to the numerical integration " Doserate dt " (or " Current dt ") with the menu item "D D" & ("Q I"). cannot be controlled with the keys on the front panel. The control keys are locked because was set into the remote mode via the RS232 interface. (In the remote mode "RS232" is indicated on the status line). Send a "Local" command via the RS232 interface, or reset the with the reset key on the rear. In the case of troubles with the processor reset the processor with the reset key on the rear. Check the selected chamber data and correction factors before performing further measurements. The LC-Display remains dark. The accumulators are discharged. Connect to the mains. With the switched on the accumulators will be recharged within 14 h. Overloading is not possible. Wait 15 min before performing further measurements. The following message appears: "F01: non valid tag NOVRAM" and further controlling is not possible. The non-volatile memory (NOVRAM) contains invalid data. In this case no resetting is possible. Please send the back to the factory. The typical life time of the NOVRAM is about 10 years (see chapter 4.3).

47 The Measurement with Ionization Chambers 3 The Measurement with Ionization Chambers 3.1 Connection of Ionization Chambers to Every PTW chamber which is mentioned in the chamber library of can be connected to. Please note the user manuals of each ionization chamber. If using a chamber not installed in the chamber library select the chamber type "*". The standard ionization chamber for is the ionization chamber type PTW with a volume of 0.6 cm 3. The chamber is vented and can be used in solid state phantoms. This user manual refers to this chamber. Check that the ionization chamber has the same connecting system as the (PTW M connectors, TNC connectors or BNT connectors). The use of an adapter cable between the two systems is not allowed because then touchable parts of the ionization chamber or the connector could be at high voltage. Only original PTW extension cables must be used between the ionization chamber and the. The total length of the connection cables must not exceed 100 m. Before connecting the ionization chamber to check the following: - The chamber is selected in the chamber library and the high voltage is adjusted - The desired polarity is selected with the switch on the rear. Now you can connect the ionization chamber to. It is not necessary to switch the off for this purpose. The ionization chamber type is ready for measuring a few seconds after connecting it to. For measurements free in air in a 137 Cs or 60 Co beam a build-up cap should be used. For ionization chamber type a build-up cap is available.

48 The Measurement with Ionization Chambers 3.2 Air Density Correction General The PTW chamber type is a "vented " ionization chamber. The pressure and temperature of a vented ionization chamber adapts to the ambient values within a few minutes. As opposed to the vented chamber the response of a sealed chamber does not vary by more than 1 % within 8 h provided the temperature is within the range of +10 C to +40 C (see IEC 60731). In both cases the air density correction has to be performed before any measurement. For the vented chamber air density correction is possible by input of temperature and pressure or by using the radioactive check device. For a sealed chamber air density correction is only possible by means of the radioactive check device. After carrying out the air density correction the message "uncorr." changes to "corr." on the right side of the measuring value Input of Temperature and Air Pressure The input of temperature and air pressure is described in chapter 2.2. The displayed correction factor is calculated according to the following formula: (273 + t) p 0 k D = T 0 p t is the temperature in C and p the absolute air pressure in hpa at the measuring point. The reference values T 0 and p 0 are: T 0 = 20 C (293 K) p 0 = hpa Additionally the reference value T 0 = 22 C (295 K) is available. The reference value has to be adjusted according to the test certificate delivered with the ionization chamber. The adjustment of the reference value is described in chapter The selected value is indicated in the correction menu.

49 The Measurement with Ionization Chambers Adjusting the Reference Temperature of The air density correction factor by input of temperature and pressure is calculated according to the formula in chapter There are two reference temperatures T 0 selectable, depending on the national requirements. The default setting for reference temperature is shown in the Air Density Correction menu. If you have to change the reference temperature proceed as follows: - Switch off. Disconnect from the mains. - Remove the front panel screws front panel and carefully remove the panel. Pay attention that you do not disconnect any cable. - On the second printed circuit board from the left you can find the 4-pole DIL switch. This switch is accessible without removing the printed circuit board. With the second switch from the top the reference is selected. Switch to the left T 0 = 293 K (20 C) Switch to the right T 0 = 295 K (22 C) - Now replace and fix the front panel with the screws. Be sure that no cable gets jammed. - Check the selection of the reference value in the correction menu. NOTE Ex factory will be delivered with a temperature of 20 C (293 K). The only exceptions are the following countries: USA, Japan and the Netherlands, where the will be delivered with a temperature of 22 C (295 K) Using a Radioactive Check Device If the ionization chamber is delivered with a radioactive check device the so-called control reading kp,0 is indicated in the test certificate of the ionization chamber. The control reading kp,0 was made by a measurement of the dose from the ionization chamber with the check source in position and subsequently correcting to the reference values of temperature and pressure. The reference values and the measuring date are indicated on the test certificate. For air density correction you have to measure the dose with the ionization chamber in the corresponding check source. The measuring procedure is described in chapter The measuring result k m is called the actual control reading.

50 The Measurement with Ionization Chambers NOTE The k m measurement is not equivalent to an interval measurement. Performing a k m measurement only takes the calibration factor into account, but not the correction factors k, k D and k p /k m. If you want to change the calibration factor and make the air density correction by using the radioactive check device, then you have to change the k p, 0 value to the same degree. calculates the control reading k p from the control reading k p,0 at the date indicated on the test certificate, taking the radioactive decay of the source into account. It is therefore essential to check for the correct actual date (the actual date is indicated in the correction menu in the line above the bottom line). For the calculation of kp the following half-live periods are used: - 90 Sr days (28.7 years) Cs days (30.25 years) - 14 C 5730 years, taken to be infinite After measuring km the correction factor kp/km is calculated and displayed in the correction menu. NOTE The thermometer should only be removed from the check device for shipment. The difference in temperature between thermometer and place of the chamber is ( ) C. For measuring the control reading km the ionization chamber and the check device should be in thermal equilibrium with the environment. A deviation in temperature of 1 C between radioac-tive check device and the environment causes an error of 0.34 %. The check device type requires approximately 3 min/k within a range of 5 C to 15 C to adapt to the ambient temperature. After use remove the ionization chamber and close the check device with the screw cap. Keep the check device at a temperature close to the measuring temperature. Do not keep the ionization chamber in the check device as it may cause damage in the case of improper handling.

51 The Measurement with Ionization Chambers 3.3 Correction Factors depending on Radiation Quality The calibration factors stored in refer to a reference radiation quality. This radiation quality is indicated in the test certificate of each ionization chamber. If measurements are performed with different beam qualities (energy, type of radiation) a correction factor for the radiation quality has to be considered. Correction factors for various X-ray qualities are listed in the test certificate of each ionization chamber. Correction factors for high energy photon and electron radiation can be determined according to national and international dosimetry protocols (e.g. DIN , IAEA Technical Report Series No. 277). Input the correction factor for radiation quality as the factor k in the correction menu (see 2.2.4). The usual range for k is 0.8 to 1.2. If a factor outside this range is entered displays a warning message. accepts values between 0.5 and 2.0. If a correction factor k unequal to 1 is entered into the hint "corrected" is displayed next to the measuring value. 3.4 Testing the Offset Current The offset current gives measuring values with the ionization chamber not irradiated. The offset current is due to leakage currents in - the amplifier - the ionization chamber - the ionization chamber cable, extension cable or cable connectors Checking the offset current is described in chapter Typical values for the leakage current of the amplifier and of the ionization chamber type PTW are listed in the technical data.

52 The Measurement with Ionization Chambers Long-term Stability The long-term stability of and the specific ionization chamber can be checked with a radioactive check device. Before the check, the must be switched on for at least 15 min and the high voltage has to be applied to the chamber for the same time. The air density correction has to be performed by entering temperature and air pressure. It is recommended to proceed as follows: - Switch on and select the ionization chamber, measuring quantity and high voltage. Connect the ionization chamber to. - Check the offset current. If necessary perform the automatic zeroing (NUL). - Put the ionization chamber into the check device. Select the measuring mode dose/doserate and the desired measuring range (usually Low). - Wait 15 min. Be sure that the ionization chamber and the check device are in thermal equilibrium with the environment. For the check device type the rate of change in temperature is about 3 min/k within a range of 5 C to 15 C to adapt to the ambient temperature. - Input the temperature and absolute pressure for air density correction. The thermometer of the check device provides the required temperature. - Start the measurement with INT for an interval time of at least 60 s. The interval time can be adjusted in the setup menu. Provided the radioactive decay is correctly considered, the standard deviation of the measuring values for 1 year should be less than 0.5 %.

53 The Measurement with Ionization Chambers Chamber Voltage and Amplifier The delivery of the correct chamber voltage (high voltage) at the measuring volume of the ionization chamber and the proper function of the amplifier can be checked by the following system test: - Set the to the chamber to be checked. - Set the measuring mode "Current" or "Doserate". Select range Low for chamber type Connect the chamber to with or without extension cable. Polarity and absolute value of the high voltage are without importance for this test. - Allow the instrument to warm up for 15 min. - Check the offset current. If necessary perform the automatic zeroing (NUL). - Choose "SETUP" in the main menu. Choose the menu "TESTS". - Choose "System Test". (This menu item does not appear if the chamber type "diode" or "diamond" have been selected.) - If for the choosen chamber the appropriate maximum high voltage Umax has not been adjusted, a warning appears to tell you that for the system test Umax will be set automatically. Press STA to continue. - Start the system test by pressing STA. automatically performs a dose measurement by numerical integration. After starting the measurement the voltage is set to 0 V and measures the according charge difference. - Read the measured value after approximately 15 s. For a PTW 0.6 cm 3 -chamber this value should be in between the limits of Table 3. If it does not, there is an interruption of the high voltage supply into the measuring volume of the chamber, or the high voltage supply or amplifier are defective. Another reason for a reading out of the limits of Table 3 is a defect at the connected chamber (e.g. damaged electrode). Therefore it is recommended to perform the system test also without the chamber connected and comparing the measuring values with the limits of Table 3. - Press ESC to quit the system test. returns to the measuring window with the parameters and high voltage used before.

54 The Measurement with Ionization Chambers Type 10001, without chamber Type 10001, with PTW Farmer type chamber Type or 10005, without chamber Type or 10005, with PTW Farmer type chamber Measuring range low medium low medium Absolute value for the system test Charge < 0.5 pc 250 pc pc < 125 pc 250 pc pc Table 3: Typical values obtained by the system test after 15 s Before the system test is performed you have to set the to the "current" mode. Please notice that the expected values differ very much depending on the chamber type and connecting system Polarity Effect The polarity effect leads to a different reading at positive and negative high voltages. The effect depends on the radiation quality. The polarity effect can be measured with as follows: - Select the desired ionization chamber in the chamber menu. Check the high voltage indicated by. Check if the positive polarity is selected (switch "HV-Polarity" on the rear). - Wait 15 min after switching on. From now on must not be switched off till the complete measuring procedure has been finished. - Connect the ionization chamber to. Pre-irradiate the chamber until the electrical potentials inside the chamber are stabilized and you get a constant current display (approx. 15 min). - Switch radiation off and wait until the displayed current has dropped to zero. If necessary perform an automatic zeroing. - Perform the dose measurement at the desired radiation quality. Note the air pressure and the temperature at the measuring point.

55 The Measurement with Ionization Chambers - Disconnect the ionization chamber from and select range High. - Now change the polarity to negative with the switch "HV-Polarity" on the rear. WARNING While changing the polarity the measuring range High must be adjusted and no chamber must be connected to! - Connect the ionization chamber to again. Pre-irradiate the chamber until the electrical potentials inside the chamber are stabilized and you get a constant current display (approx. 15 min). - Switch radiation off and wait until the displayed current has dropped to zero. If necessary perform an automatic zeroing. - Now repeat the dose measurement. Note air pressure and temperature at the measuring point. - Correct the readings for positive and negative voltage for air density and compare the corrected readings. - Disconnect the ionization chamber from and select range High. - Set the high voltage back to positive polarity Display The reading can be checked as follows: - Select the menu item "SETUP" on the main menu (see chapter 1.3.1). - Select the menu item "Tests". - Select the menu item "Display Test". - Check the correct display of each figure as well as the prefix (f, p, n, µ, m, k, M, G, T) of the measuring unit.

56 Maintenance 4 Maintenance 4.1 Drying Device The drying device is used to protect the amplifier against humidity. The drying device can be examined at the bottom of. If the humidity inside the amplifier is less than 40 % the color of the drying device is blue. If the humidity exceeds 40 % the color changes to pink. In this case exchange the drying device. As a rule the life of the drying device is at least 5 years. Drying devices can be ordered from PTW via ordering number L To exchange the drying device proceed as follows: - Switch off. - Disconnect from the mains. - Use the packing of the new cartridge as a screw driver for removing the used cartridge, turn the screw to the left. - Remove the black O-ring and the white plastic ring from the used cartridge. - Remove the packing container from the new cartridge by turning to the left. Then fix the white ring and finally the black O-ring. - Put the new cartridge into the as fast as possible. NOTE 1.) Exchange the drying device at low humidity in the environment. 2.) Be sure that is switched off to prevent contact to high voltage during the exchange of the cartridge. 3.) Used drying devices cannot be dried by heating, they must be replaced.

57 Maintenance 4.2 NiCd or NiMH Rechargeable Battery The NiCd or NiMH battery L of allows operation for (7... 9) h. operates at its full performance until the display goes blank. As a warning "LowBat" is indicated about 20 min before the display goes blank. In this "stand-by" mode the input current is reduced to a few ma. To avoid an over-discharging of the batteries the should be switched off (or connected to the mains) after the display has gone blank. The battery is being charged when the is connected to the mains and the is switched on (the display is illuminated). The charging takes about 14 h. is protected against overloading. To check the charge level disconnect from the mains and check whether "LowBat" appears. To exchange the batteries, if necessary, proceed as follows: - Switch off. - Disconnect from the mains. - Remove the plate at the rear and take out the 8 batteries. - Now put in the new batteries. Take care to keep the correct polarity, which is indicated on the stickers. The four upper batteries have to be put in with the positive side first whereas the lower four batteries with the negative side first. Use only NiCd or NiMH batteries. - Replace the plate with the four screws. NOTE For the rechargeable batteries to keep their full capacity, they should be fully discharged and then recharged again approximately every 3 months.

58 Maintenance 4.3 Non-volatile RAM uses the non-volatile memory (NOVRAM) to store the calibration factors and the ionization chamber data. After switching on the data are checked to their validity. If non-valid data are detected the message "F01: non valid tag NOVRAM" appears. Data loss is possible at the end of the life time of the NOVRAM. The typical lifetime is about 10 years. We recommend to replace the memory for reasons of precaution at which data can be transferred. shall be sent back to factory for memory replacement. 4.4 Repair of Calibrated Dosemeters In your country it may not be allowed to open the housing of a calibrated dosemeter without loosing the validity of the official calibration. Please be aware of the procedure valid in your country. 4.5 Electrical Safety is a Class I equipment. The housing and all accessible parts are connected to the protective earth conductor or connected to low voltage with the opposite pole also connected to the protective earth conductor. The maximum current of the high voltage supply for the ionization chamber is limited to 0.5 ma. In the case of damage or touching of conducting parts the current flows directly or via the protective earth conductor to earth. Connection to the mains is made by a 3pole detachable power supply cord and a mains socket with protective earth conductor. WARNING Disconnect from the power line and switch the power off before opening the housing.

59 Maintenance 4.6 Change of the Mains Voltage operates with 115 V or 230 V. The voltage adjusted ex factory is indicated on the sticker at the rear. To change the voltage proceed as follows: - Switch off. - Disconnect from the mains. - Remove the 4 screws of the upper cover of and take the cover away. - There is a red slider in the black housing in the middle of the printed circuit board on the right side near the upper edge of the board. Look from the right side of at the positioning of the slider. Slider to the rear ( rear panel): 230 V Slider to the front ( front panel): 115 V - Remount the housing cover. - Fit in the correct fuses at the mains socket at the rear: 230 V: 160 ma, slow blow fuse 115 V: 315 ma, slow blow fuse - Correct the sticker on the rear to the correct mains voltage. 4.7 Fuses 3 slow blow fuses are used accessible from the rear. Disconnect from the power line and turn the power off before replacing the fuses. Fuses for the high voltage supply: Fuses for 230 V: Fuses for 115 V: 20 ma, slow blow fuse 2 x 160 ma, slow blow fuse 2 x 315 ma, slow blow fuse

60 Maintenance 4.8 Spare parts list Designation PTW No. resp. Ordering information Desiccant for L Sealing ring for drying device L Distance ring for drying device Drawing No Fuse set for 230 V 2 x L251018, 1 x L Fuse set for 115 V 2 x L251009, 1 x L Set of NiCd or NiMH batteries 8 x L Carrying handle L Complete assemblies LC-Display (with EL-foil) Keyboard Power supply board Switched power supply L UDF T UDE-B T UDN-A T

61 Technical Data 5 Technical Data 5.1 Dosemeter Name: Producer: Mode of operation: Application: PTW- dose and dose rate measuring device, type (connecting system: M), type (connecting system: TNC) type (connecting system: BNT) PTW-Freiburg permanent operation Reference class dosemeter for dose and dose rate measurement in radiotherapy to IEC in diagnostic radiology to IEC in radiation protection for stationary use inside buildings to IEC Charge and current measuring device Electrical safety class: I acc. IEC Measuring quantities and units: Measuring modes: Sampling rate in the integration mode: Max. integration time: Interval time: - absorbed dose to water [Gy] - absorbed dose to air [Gy] - air kerma [Gy] - photon equivalent dose [Sv] - exposure [R] - the corresponding dose rates - charge [C] - current [A] - dose or charge - dose rate or current - numerical integration of dose rate or current 1 khz 18 h 6 s s

62 Chamber voltage: Technical Data 0 V... ± 400 V, increments of 50 V Accuracy of chamber voltage: 1 % Accuracy of the ratio of two chamber voltages: Limitation of the current supplied by high voltage: 0.5 % typ. 0.5 ma by semiconductors (1.0 ma max.); 20 ma by slow-blow fuse (see rear panel) Measuring ranges: see table 1 (chapter 1.1.3) Accuracy of current and charge measurement: Offset current (zero drift): Zeroing: ± (0.5 % + 1 count) ± 1fA automatically within 75 s Non-Linearity: ± 0.5 % acc. to IEC Long-term stability: Nominal conditions for operation Temperature: Humidity: Air pressure: Nominal conditions for transport and storage Temperature: Humidity: Air pressure: Display: Response time: Time constant for measuring current or dose rate: ± 0.05 % p.a. 10 C C 10 % % rel. humidity; max. 20 g/m³ ( ) hpa ( ) C ( ) % rel. humidity; max. 20 g/cm³ ( ) hpa 4 digits 1.5 s in all ranges Measuring Range Low: 350 ms Medium and High: 200 ms Warm-up period: 15 min (see figure 5)

63 Dimensions: Weight: Lifetime of the non-volatile memory: Power supply: Desiccant: Technical Data width 257 mm height 152 mm length 262 mm 6.4 kg typically 10 years 115 V / 230 V ( )%; Hz, NiCd or NiMH-Batteries (2.2 Ah, IEC 285-2: KR 27/50) (operation independent of mains h). PTW order number L Size 10-17; PTW order number L137004

64 Technical Data Figure 7: Typical offset current versus time after switching on the at 23 C. The maximum value is about 300 fa immediately after switching the unit on. The warm-up period is 15 min.

65 Technical Data Figure 8: Typical offset current versus time after switching on a warmed-up which has been switched off for 10 s. After switching on again the warm-up period should also be 15 min.

66 Technical Data 5.2 Circuit Diagrams Diagram No. Function Topology of the Parts Amplifier Logic UDA-A CPU /230 V Mains-/Charging Unit UDE Block Diagram Amplifier and Logic Block Diagram Overview Potentials NOTE 1.) Service is only allowed for authorized persons. 2.) Under no circumstances the amplifier box may be opened, because the isolation properties will get worse. Service for the amplifier must be done in the factory. 3.) Replacing parts on the CPU or amplifier boards may cause a change of internal calibration data. In this case a new calibration of the electronics must be performed in the factory.

67 Technical Data Drawing No Topology of the Parts

68 Technical Data Drawing No Amplifier Logic UDA-A

69 Technical Data Drawing No CPU

70 Technical Data Drawing No /230 V Mains-/Charging Unit UDE

71 Drawing No Technical Data Block Diagram Amplifier and Logic

72 Technical Data Drawing No Block Diagram

73 Technical Data Drawing No Overview Potentials

74 Appendix: Potential Conditions Appendix: Potential Conditions The polarity of the polarizing voltage of PTW dosemeters is defined by the potential of the chamber wall with respect to the guard. Both positive and negative polarizing voltages are shown in Figure 9. Connecting system BNT or TNC: Collecting electrode and guard on high voltage. For positive high voltage (HV) the potentials of collecting electrode and guard are negative with respect to earth potential by the value of the HV. The outer electrode (chamber wall) is on earth potential. Connecting system M: Collecting electrode and guard on earth potential. For positive HV the outer electrode (chamber wall) is positive with respect to earth potential. In either case, negative ions generated in the chamber volume will be attracted by the chamber wall when a positive polarizing voltage (HV switch at + position) is applied and to the central or collection electrode when a negative polarizing voltage (HV switch at - position) is applied. POS NEG Figure 9: + Positive and negative polarizing voltage

75 Appendix: China Electronic Industry Standard Compliance Appendix: China Electronic Industry Standard Compliance 附录 : 中华人民共和国电子产业标准 This Supplement concerns China Electronic Industry Standard Compliance 此附录涉及中华人民共和国电子产业标准的相关规定 The following product pollution control information is provided according to SJ/T Marking for Control of Pollution caused by Electronic Information Products. 根据 SJ/T 标准规定的 电子信息产品污染控制标识要求 特提供以下有关产品污染控制方面的信息 1. Explanation of Pollution Control Label 污染控制标识说明 This symbol indicates the product contains hazardous materials in excess of the limits established by the Chinese standard SJ/T Requirements for Concentration Limits for Certain Hazardous Substances in Electronic Information Products. The number in the symbol is the Environment-friendly Use Period (EFUP), which indicates the period during which the toxic or hazardous substances or elements contained in electronic information products will not leak or mutate under normal operating conditions so that the use of such electronic information products will not result in any severe environmental pollution, any bodily injury or damage to any assets. The unit of the period is Year. In order to maintain the declared EFUP, the product shall be operated normally according to the instructions and environmental conditions as defined in the product manual, and periodic maintenance schedules specified in Product Maintenance Procedures shall be followed strictly. Consumables or certain parts may have their own label with an EFUP value less than the product. Periodic replacement of those consumables or parts to maintain the declared EFUP shall be done in accordance with the Product Maintenance Procedures. This product must not be disposed of as unsorted municipal waste, and must be collected separately and handled properly after decommissioning. 该标识表明本产品含有的有毒有害物质超出 SJ/T 标准规定的 电子信息产品中有毒有害物质的限量要求 标识中的数字为本产品的环保使用期限 ( EFUP ), 表明在正常使用的条件下, 电子信息产品内含的有毒有害物质或元素不会发生外泄或突变, 用户使用该电子信息产品不会对环境造成任何严重污染或对人身 财产造成任何严重损害的期限 单位为年 为保证所声明的环保使用期限, 应按产品手册中所规定的指示和环境条件进行正常使用, 并严格遵守产品维护程序中规定的定期维护和保养日程 产品中的耗件或某些零部件可能具有单独的标识, 其环保使用期限有可能短于产品本身的环保使用期限 应按产品维护程序定期更换这些耗件或零部件, 以保证所声明的整个产品的环保使用期限 本产品在使用寿命结束后不可作为普通生活垃圾处理, 必须另行收集并作妥善处理