Digital Image Management: the Basics Napapong Pongnapang, Ph.D. Department of Radiological Technology Faculty of Medical Technology Mahidol University
Outline From screen/film to digital radiography PACS/Tele radiology Setting up digital department Digital Imaging
Why do we go for Digital? Limitations of film-screen characteristics Limitation of physical storage space in hospital Need for electronic type imaging (PACS) Workflow convenience Image Quality Dose efficiency
PACS/Tele Radiology Picture Archiving and Communication System (PACS) A PACS system displays, archives and communicates medical digital images Tele Radiology The transmission of radiological patient images, such x-rays, CTs and MRIs from one location to another for the purpose of interpretation and/or consultation
What is PACS? P: Picture, Images & Reports A: Archive, Online, Near line, Offline C: Communication, Networking, Transfer Protocols S: System, Components & Architecture PACS: for storage and distribution of images and information when necessary
PACS Simple Look CTs DICOM CRs MRs DICOM Study Server DICOM Work Station Diagnostic Station
Importance of PACS Improve flow patient management, timing report from radiologists and work flow Enable the image comparison between pre and post treatment Solving problems of film lost, misplace and storage space Improve image and patient related data storage and accessibility
PACS: Small or Large Web Server Distribution
Scale of PACS Hospital Size (No. of beds)/ Exams per year Radiology Department ( No. of Modalities) No. of Switches Considerations: System connectivity, expandability, reliability and cost-effectiveness
1D, 2D, 3D, 4D Different DICOM Modality type: Cardiac / PET / 4D U/S.. Image size: Resolution and bit depth Image quality: Bit Depth and resolution Color / Monochromatic Exam. Size: image size x no. of images Structured Reports New DICOM IOD: Endoscopic & Microscopic images / ECGs / Security Profiles.. Types of images
PACS Consists of different components Radiologist reading stations Clinician review stations Web access Technologist/Radiographe r quality control stations Administrative stations Archive systems Multiple interfaces to other hospital and radiology systems 11
Properties of good PACS Highly availability: Fault Tolerant Enough bandwidth for sending/receiving data: Networking Flexibility: Process Connectivity with HIS : Application DICOM compatibility: Application Scalability: Storage Network-wide connection: Intranet/Application
PACS connection with HIS/RIS HIS RIS Study Server RIS/PACS interface Work Station Work Station Work Station CTs CRs MRs
PACS connection with HIS/RIS HIS: Hospital Information System with all patient data RIS: Radiology Information System connects with HIS for example; name, HN RIS: Saves additional information that is not available in HIS for example, image/exam diagnostic results PACS can connect and use data from HIS/RIS
PACS Central Architecture DICOM Modality Diagnostic Workstations (DICOM) Non-DICOM Modality Gateway or Frame Grabber Image Server (RAID) Clinical Workstations (DICOM) Diagnostic Workstation Film Digitizer Web Server Computed Radiography or DR CR/ DR QA Workstation Data Base Server Archive RIS
PACS Distributed Architecture DICOM Modality Non-DICOM Modality Gateway or Frame Grabber Diagnostic Workstations (DICOM) Clinical Workstations (DICOM) Web Server CR QA Workstation Film Digitizer Data Base Server Diagnostic Workstation Computed Radiography Archive RIS
Storage Device (Long Term) HIS/RIS Interface (Broker) Database Server RAID MOD DLT DG RIS W/S PCs CR QA Film Digitizer Frame Grabber C T M R R& F NM CR XRAY US
Display HIS/RIS Interface (Broker) SAN/NAS Database Server RAID MOD DLT Diagnostic W/S Dedicate W/S DG RIS W/S PCs CR QA Film Digitizer Frame Grabber C T M R R& F NM CR XRAY US
PACS Workstation PACS Server: Standard Server Class machine (run 24/7/365) One or two Intel Xeon processors with Intel Extended Memory 64 technology Up to 16 GB of ECC DDR-2 memory One PCI Express x4 slot, three 64-bit PCI-X slots, and two legacy PCI slots Up to 4 internal SATA or 5 SCSI hard drives PCI Express graphics (x16) Integrated dual-channel SATA/150 controller with RAID and dual channel Ultra320 SCSI controller PACS Workstation: an example of Intel Core 2 Duo class machine General Use PCs: separation from general use and clinical use Concept of Machine Separations Security Performance Cost
Diagnostic Medical Monitor LCD must support 3-5 MP at Native Resolution Backlight stabilization QC/QA of display uniformity
Video Card Must: Provide the high level of image quality and performance required for diagnostic excellence Support 10-bit capabilities, and supports a variety of up to 5 MP grayscale displays, making them the ultimate solution for precise and accurate display representation Example: Matrox MED series $1000
Benefit of PACS: Source: www.medicalimagingtalk.com
Benefit of PACS: Workflow Source: Philips
Benefit of PACS: Real-time clinical consultation Radiology PACS Clinician
How to get start? Set up project management team Project planning and execution Training
A step further digital modality Digital ready modalities CT MRI Ultrasound NM Modalities that may need to be replaced Plain film
Digital Radiography
From screen/film to DR Images from analog to digital Image viewing, transferring and archiving Digital image processing Factors affecting techniques: Dynamic range Detector energy response Detector efficiency
DR: Acquisition Technology Photostimulable Phosphors ( CR or PSP ) Photostimulable phosphor plates Flat-panel Detectors Direct DR (DDR): Amorphous Selenium Detector matrix of transistors, without photon conversion layer Indirect DR (IDR): Amorphous Silicon TFT or CCD with CsI conversion layer
Interesting Points Screen-film characteristics are different from digital radiography Among types of digital radiography, they are different Technical settings by Technologist are different for conventional vs. digital imaging QC procedures/film Reporting for each type of these modalities are different
Transforming to Digital : Workflow changes
Workflow: DR vs. Conventional CONVENTIONAL X-RAY IMAGING SYSTEM X-RAY TUBE CASSETTE SCREEN X-RAY FILM PROCESER X-RAY IMAGE
Workflow: DR vs. Conventional DIGITAL X-RAY IMAGING SYSTEM
DR IMAGE PROCESSING FLOW DIAGRAM ID Station Imagespecific parameters Image Readout Raw image Image Enhancement Processed image Image Output Reduced image Analysis Imagederived parameters
Workflow: Computed Radiography (CR) Plate Reader ADC / EDR PACS Soft-Copy Read Hard Copy QCW Network
Workflow: Flat Panel System Technique Image Processing (QC) & Acquisition PACS Image Display Hard Copy QCW WLM (RIS)
What about dose?
It has been proved that DR reduces dose Bacher K., et, al.2003;181(4):923-9. Dose reduction in patients undergoing chest imaging: digital amorphous silicon flat-panel detector radiography versus conventional film-screen radiography and phosphor-based computed radiography. RESULTS: The amorphous silicon flat-panel detector radiography system allowed an important and significant reduction in both entrance skin dose and effective dose compared with the film- screen radiography (x 2.7 decrease) or computed radiography (x 1.7 decrease) system. In addition, image quality produced by the amorphous silicon flat-panel detector radiography system was significantly better than the image quality produced by the film-screen or computed radiography systems, confirming that the dose reduction was not detrimental to image quality. Bacher K., et, al.2006;187(3):630-7.image quality and radiation dose on digital chest imaging: comparison of amorphous silicon and amorphous selenium flat-panel systems RESULTS: The amorphous silicon flat-panel system allowed an important and significant reduction in effective dose in comparison with the amorphous selenium flat-panel system (p < 0.0001) for both the posteroanterior and lateral views. In addition, clinical image quality analysis showed that the dose reduction was not detrimental to image quality.
It has been proved that DR reduces dose Hamer OW., et, al. 2005 Nov;237(2):691-700. Chest radiography with a flat-panel detector: image quality with dose reduction after copper filtration. RESULTS: Subjectively equivalent chest radiographic image quality was found with estimated 30% reduction after addition of 0.3-mm copper filtration with flat-panel cesium iodideamorphous silicon technology. dose BJR (2007), 984-987 RESULTS: Preliminary findings suggested that possible 50% dose reduction can be achieved.
Why dose reduction? Reduce dose = reduce stochastic risks Dose optimization Pediatrics patients
PACS and patient dose monitoring Regulatory requirements Accreditation requirements Liability and Public Relations Research Quality Assurance Awareness & Patient Safety Individual Patient cumulative dose record
Dedicated dose tracking software Integrate dose metrics from imaging systems or PACS typical formats: DICOM RDSR preferred Integrate with PACS, RIS, EMR Analysis capabilities Selection of Reference Doses Automated notification
Conclusions Digital radiography is different from conventional screen/film system in dynamic range, detector response and the form of images. Transition from analoqe to digital imaging will result in work flow changes DR technologies include direct and indirect systems for x- ray detection, and the indirect systems include PSP and flat-panel detectors PACS helps manage image archiving and distribution