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IMRT Quality Assurance

IMRT Quality Assurance. Niko Papanikolaou, PhD Associate Professor and Chief of Medical Physics Department of Radiation Oncology University of Arkansas for Medical Sciences Little Rock, Arkansas, USA. Outline.

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IMRT Quality Assurance

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  1. IMRT Quality Assurance Niko Papanikolaou, PhD Associate Professor and Chief of Medical Physics Department of Radiation Oncology University of Arkansas for Medical Sciences Little Rock, Arkansas, USA

  2. Outline • Discuss the QA procedures that we follow in our clinic for patient specific IMRT QA • MLC based planning on Philips Pinnacle RTP delivered on a Varian 2100EX • Tomotherapy based planning and delivery using the HiART Tomotherapy system

  3. Equipment and Tools • Phantom(s) They come in many sizes and shapes and the question is which one is the right one for the job ? A simple phantom that is easy to use, fast to setup and large enough to accommodate the typical patient dose distributions

  4. Equipment and Tools • Ion chamber(s) A reliable ion chamber that is not too small but not too large either. The choice of ion chamber is not as critical, but a good choice could make a difference on certain occasions Ion chamber systems like the MapCheck are also available for QA

  5. Equipment and Tools • Film The choice of the film is very important. But even more important is the calibration of the film and the maintenance of the film processing environment

  6. Very small energy dependence

  7. Equipment and Tools • Analysis Software and Scanners There are several software options for film analysis and IMRT QA currently available. For a routine task as such the important factors are efficiency, ease of use, accuracy and documentation

  8. Independent MU Calculations

  9. The Pinnacle IMRT QA

  10. P3IMRT QA tools • Automatically generate orthogonal DRRs to verify isocenter placement • Use the profile tool to view the dose profile across the plan between any two points • Compute the dose distribution for any beam at a given depth in a flat water phantom • Compute the dose distribution at any plane in the dose matrix • Transfer the beams from an IMRT plan to a user-defined QA phantom • Export distributions for comparative analysis

  11. Solid phantom Film Planar dose verification (single beam) Planar dose map

  12. Solid phantom Film Planar dose verification (all beams) Planar dose map

  13. Planar Dose Comparison RTP distribution Film distribution

  14. epin utility

  15. Patient

  16. Patient

  17. The Tomotherapy IMRT QA

  18. Tomotherapy – Phantom

  19. Tomotherapy – Profile Display

  20. Tomotherapy – Profile Display

  21. Tomotherapy – Isodose Display

  22. Tomotherapy – Gamma Display

  23. Conclusions • State of the art algorithms for photon dose computation should be used for both conventional and IMRT planning • What you calc is what you get … • Better outcome analysis and studies • In our experience both the Tomotherapy and the Pinnacle planning systems have a comprehensive set of tools to perform routine patient QA for IMRT

  24. Conclusions • The user has to decide what is important to evaluate when making a measurement. Is it the effect of the inhomogeneity, the motion of the MLC, the angle of beam incidence, the transfer of the plan to the RV system or perhaps all of the above ….

  25. Thank you

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