15/7/2015. Key Problem Address. Introduction. Outline

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1 R&D 214 Determination of Crack Area on Lead Apron used in Diagnostic Radiology Norriza Mohd Isa Medical Physics Unit Agency Nuclear Malaysia M.J. M. Isa 1, R.Yusof 2, M.H. F. Ahmad 3, M. F. A. Rahman 1, Z. Jamaluddin 1, M. K. M. Zin 1, S. A. Azizan 1, A. Hashim 1,,M.M.A. Jalil 1, M.Nahun 1 Key Problem Address Until recently there was a little information when the PPE should rejected But no guidance & proper procedure readily available for inspection of PPE in Malaysia 1 Malaysian Nuclear Agency, 43 Kajang, Selangor. 2 Faculty of Applied Sciences, Universiti Teknologi MARA, 445 Shah Alam, Selangor. 3 Department of Radiology, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, Bandar Tun Razak, 56 Cheras Kuala Lumpur. Outline Introduction Objectives & Background Materials & Methods Result & Discussion Conclusion References Introduction Personnel protective equipment (PPE) are used to reduce radiation exposure to worker PPE (eg. lead aprons, gloves, and thyroid shield) utilized by x-ray workers must be periodically evaluated for damage. Sometimes PPE is damaged when not properly handled or stored. Lead aprons sometimes are folded or dropped on the floor in such a way as to cause sharp bends in the vinyl that deteriorate the leadimpregnated vinyl. A typical lead apron consists of lead-impregnated vinyl or rubber sheets finished with an outer layer of nylon fabric. Protection Against External Radiation Exposures Attenuation Radiation Law Shielding Source Distance Time Appropriate Shielding Shortest Time Maximum Distance X o X T μt X = e T X o Ketebalan, T X o = Kadar dos sebelum perisai X T = Kadar dos selepas perisai T = Ketebalan Perisai μ = Pekali pengecilan jisim 1

2 Personnel Protective Equipment Mobile shielding and leaded aprons play an important protective role in certain applications. Normal Practice Procedure Fluoroscopy Image Output Fluoroscopy/C arm CR Image Output Computed Radiography (CR) 7 MS 838:27 Lead apron not less than.25 and should be.5 mm (esp. for fluoroscopist) A double lead apron should be worn by personnel who may receive radiation posteriorly, anteriorly and laterally. The Use of Lead Protective Equipment Human holders can be used and must be provided with adequate protection,.5 mm lead when standing in the primary beam and.25 for scatter (secondary radiation). The minimum requirement is.25 mm of lead equivalent shielding for an occupational worker, not standing in the primary beam. Inspection and testing of protective clothing must be performed as described by National Protocol (if available)/ International guideline/ manufacturer. Standard Procedure by Joint Commission on the Accreditation of Healthcare Organizations (JCAHO) Accreditation Manual for Hospitals (JCAHO 21) Parameter Will coming regulation 21.. Draft Atomic Energy Licensing (Medical, Dental And Veterinary Usage of Radiation) Regulations 21_, Acceptable Level Remedial Level Suspension Level Frequency International Reference Protective No cracks; N/A Cracks Yearly Health Devices (Lead Aprons/Thy roid Shield/Half Apron) <15 mm2 over the critical area for apron, <11 mm2 for thyroid shield observed > 15 mm2 over the critical area for apron, > 11 mm2 for thyroid shield Physics Society and Journal- Inspection of Lead Aprons: Criteria for Rejection Kent Lambert and Tara Mc Keon (21) 2

3 (PERLINDUNGAN SINARAN KESELAMATAN ASAS) 21 Personal protective equipment 2. (1) The licensee shall ensure that all personal protective equipment is maintained in proper condition and where appropriate, is tested at regular intervals; Objectives To develop procedure to determine leakage or crack area of PPE (eg. Lead apron). To assist the MOH in establishing the radiation PPE inspection program in Malaysia (Determination of crack areas/ holes). EQUIPMENTS X-ray tube system General X-ray System TOSHIBA KXO-5S Model DRX-3724HD; S/N: 13G195 INSERT MODEL DR-3724H; S/N: 3G16 kv/ma/kw Range: 15 kv/ 32 ma/ 5 kw CR system Care stream single CR Reader: Direct View Classic CR (mammography quality) S/N: Carestream Imaging Plate (Casette) Acquisition Monitor Other test tools Methods Set up standard beam (8 kvp, 25mA,.2s at 1 cm FDD) with some known 1 lead sheet thickness to plot calibration (pixel value versus Pb thickness). Expose& determine a known square hole area of Pb sheet to ensure the reliability 2 of Matlab software output in term of area determination. 3 Expose PPE (lead aprons) with the standard beam 3

4 Experiment Set-up Obtain digital image of PPE using Computed Radiography (indirect digital radiography) system. Convert CR digital image (dcm) to BMP format Determine crack or defect area using Matlab software. Staffs are setting up the equipments and the lead apron sample for the testing Types Lead apron samples with various thickness and manufacturers Aging Thicknesses (mmpb) No. of samples Results & Discussion New >> years New.3 5 >> 2 years.5 3 New.5 2 After 2 years After 9 years.3mmpb.3 mmpb.5 mmpb.5 mmpb.25 mmpb.3 mmpb 3D image for the New lead apron (.5 mmpb) 35 CR y =.29x x R² =.978 CR 15 Poly. (CR) Dose in 4

5 Gray Scale CR Calibration Curve for 8 kvp 25 2 Hubungan Dose denagn Ketebalan Filter y = 26.3x R² = Gray Scale CR Bacaan Dose (ugy) 15 1 Hubungan Dose dengan ketebalan filters Linear (Hubungan Dose dengan ketebalan filters) Plumbum Thickness (mm) filters (mmpb) rate (It/Io) Ln dose Calibration graph for Lead Apron using 8 kvp Pb thickness(mm) Thickness result for.5 mmpb lead apron >> GL6gb Please give filename and write together with file format?: mek8.xlsx r = 9 c = 5 Do you want to determine ln doserate from the thickness value of the object or otherwise? Type(y/n): n Answer =n What is ln doserate division you obtained?: The thickness of glove is : lead equivalent (mm) Do you want to determine ln doserate from the thickness value of the object or otherwise? Type(y/n): n Answer =n What is ln doserate division you obtained?: The thickness of glove is : lead equivalent (mm) Calibration Curve for Crack Area Evaluation No Lead sheet Mean thickness Pixel Value (mm) Gray Scale :-255 : Black Image 255: white Image Square hole area on a Pb sheet as a reference tool >> leakareastd please give filename and write together format file: 8 kvp s.bmp ry =65 cx =64 what is number of pixels y-exist for the reference object: 65 what is size of the reference object in cm: 1 The conversion factor index : cm per pixel for y-exist what is number of pixels x-exist for the reference object: 64 what is size of the reference object in cm: 1 The conversion factor index : cm per pixel for x-exist IND = 2.438e-4 MAl =.6697 R = 439 The area is :.9791 cm2 The area is : mm2 >> Digital Image of the tool 5

6 Range of PV range selection based on lead apron image of lead sheets KVp:8 mas: 25 ma &.2s HVL:2.882 mmal Pb equivalent thickness (mmpb) Pixel Value (PV) Range Mean Min Max Example of software output >> leadleak2 please give filename and write together format file: S1,im2.bmp ry = 25 cx = 248 what is number of pixels y-exist for the reference object?: 21 what is size of the reference object in cm?: 1 The conversion factor index : cm per pixel for y-exist what is number of pixels x-exist for the reference object?: 627 what is size of the reference object in cm?: 1 The conversion factor index : cm per pixel for x-exist IND = e-6 The area is :.3872 cm2 The area is :3.872 mm2 Defect/ Leakage areas of lead aprons Aging Stated Mean Range Area (mm 2 ) of Thicknesses pixel Pixel Lead (mmpb) of value value PV: PV: PV: PV: PV: PV: PV: PV: Total apron Lead aprons area s (leak) (mm 2 ) >> ,8 years (more than 15mm 2 ) New ,1 11, >> , ,92 years ,2 New , Conclusions The lead apron more than 9 years has cracks more than 15mm 2 in area close to critical organs (as mention by Lambert and McKeon, 21). Therefore it should be replaced or rejected for optimal protection. The new lead aprons have uniform pixel values for whole area and no decreasing for its thickness But the lead apron more than 2 years it started decreasing of their thickness of lead. In order to ensure that PPE is comply with MOH requirement for safety and Health purposes; PPE should be undergo inspection periodically (at least once a year or upon request by users). How to Care PPE Inspect PPE for defect (tears, perforations & thinning creases) If not use please hang lead apron by both shoulder on a rack Keep PPE at clean and free of chemicals area Do not lay PPE over any processor system and source of heat Do not puncture PPE with any sharp objects Do not put PPE on the floor or crinkle it Do not clean it with any chemical Hand wash PPE with mild soup & water, rinse with a damp cloth and then hang it to air dry. 6

7 References 1. Joint Commission on Accreditation of Healthcare Organizations (JCAHO). Accreditation Manual for Hospitals, Environment of Care Section 1.6. Chicago:JointCommission on Accreditation ofhealthcare Organizations; Lambert KN, McKeon T. Inspection of lead aprons: Criteria for rejection. Health Phys (Supplement 1) Operational Radiat Safety 8:5:367-S69: Acknowledgement Thank to staff of Radiology Department, HUKM and Putrajaya Hospital for their cooperation in giving us borrowing some lead aprons as samples to undergo the test for this project. Future work 1. Improve existing output results presentation of the test by using Matlab Graphical User Interface GUI approach. Thank You for your attention 2. Extending the standard beam for other beam quality (e.g 9 kvp) 7