EPID BASED QA The future ?

Motivation – reduce QA burden Too much QA.

How do we do it in risk laden industry ? Can we just do less ? Current approaches based upon guidelines. IPEM AAPM IAEA, IEC etc Possible but in reality difficult to justify moving away from recommended (sometimes mandated) schedules

How do we do it in risk laden industry ? Can we just do less ? Risk based approaches IPEM – Report 92 Deterministic approach, couldn’t come up with clear recommendations for change. AAPM FMEA/FTA approach used in other high risk industries. Report not published after 10 years. Separate publications focussed on new clinical techniques

Can we do it more efficiently ? Need better/less tools. Need more efficient analysis. Increased automation. Reduced human involvement.

Electronic Portal Imaging Devices EPIDs are the obvious choice High resolution diode array All modern linacs have them. Maintained. Easily deployable. Data (images) are readily analysable.

Electronic Portal Imaging Devices EPID based QA is nothing new. Field Size Symmetry/Flatness MLC Accuracy Output Several commercial products available Usually deployed in a traditional paradigm.

Why the traditional approach ? Break the link between the acquisition of data and the analysis of that data. Make the data acquisition so efficient that it can be incorporated into another clinical process with minimal impact on that process. If a process has minimal cost you can collect machine performance data more frequently.

Machine Performance Data Field Size Output Symmetry/Flatness Wedge Factor Energy MLC accuracy

Our Aim To incorporate EPID QA on a regular basis to assess linac performance and improve the efficiency of QA without the use of phantoms. Create a framework and communications pathway that fully automated the QA process Simple and efficient implementation and management Minimal impact on clinical availability

Implementation 2 images per energy – open & wedged delivered through Mosaiq and captured using iCOM, as part of morning run-up. Images auto-forwarded to a QA server. At a scheduled time the image sorter routine determines analysis required from the ‘rules’ file and calls the appropriate analysis routines. Results stored in a database. Results analysed at a later date. Can perform analysis ‘on demand’ if needed.

EPID QA Framework Clinical systemsEPID based QA User-end results Mosaiq QC Patient loaded and QA beam run Image acquired on iView Database PukkaJ DICOM Store ICOM Auto- forward Conquest DICOM Server Image Sorter QC Database Flatness/ Symmetry Wedge Factor Energy Output MLC Picket fence Analysis ModulesResultsImage SortingImage Acquisition Pass/Fail Results Modules Complex analysis Plan and beam name defines analysis routine Rules set in PukkaJ to auto-forward to Conquest DICOM server if Patient ID/ Study ID is correct ICOM link to iView ensures patient demographics are correctly set IMRT beam prescriptions written and imported into Mosaiq Sorts new images and checks rules file for analysis to perform Image sorter run at scheduled times. Results and calibration data stored in database tables. Access only by Admin Separate modules for each analysis, each compiled and tested individually Read only access to the results database User end interface to view results export data. All image analysis and results performed automatically without user input. Code compiled and sits on network. GUI allows user to review data and is tailored to needs of the user

EPID based QA QC Database Flatness/ Symmetry Wedge Factor Energy Output Analysis ModulesResults Rules file determines the analysis performed Results and calibration data stored in database tables. Access only by Admin Separate modules for each analysis, each compiled and tested individually Image Sorter Rules File Config File Images Patient IDStudy IDBeam IDNo ImagesFunction ZZEPQAGantry0EPQ14/6MV_Gantry04Flatness/symmetry.exe ZZEPQAGantryAllEPQ15/6MV_GantryAll20Flatness/symmetry.exe Gantry 0, Col 0 Open / Wedge G0, C0 Open C0Open All Image Sorting Sends images to appropraite modules based on rules file Image Sorter Program

Analysis Options Output, Energy, Flatness, Symmetry – Implemented in version 0.1 of the GUI. Wedge factor and field size not displayed currently. MLC Calibration assessed separately

Current Status All linacs now being monitored. Images taken during morning runup. Results monitored prior to PM. Results compared retrospectively against conventional QA data.

Target Eventual aim is to develop a system which reduces the amount of time spent performing ‘conventional’ QA. If we have EPI QA evidence that a parameter has not changed since the last time it was measured we should not need to re-measure it. Potential to reduce QA times from 5-6 hours to 1.5 to 2 hours.

Future Goals Develop a web based gui. Incorporate MLC QA. Incorporate into the clinical QA process.

What will QA look like in the future ? QA Conventional QA EPID based QA Portal Dosimetry Risk based QA

Thanks to Aaron Huckle Jonathan Sykes Dan Johnson Phil Rixham Gillian Ward Samir Dawoud Radiotherapy Technical Services Ashraf Esmail Isobel Bond

Thank You