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Program Information

Developments in Clinical Reference Dosimetry


B Muir

M Mitch

S Kry
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V Feygelman




B Muir1*, M Mitch2*, S Kry3*, V Feygelman4*, (1) National Research Council, Ottawa, ON, (2) Nat'l Institute of Standards & Technol, Gaithersburg, MD, (3) The University of Texas MD Anderson Cancer Center, Houston, TX, (4) H. Lee Moffitt Cancer Center, Tampa, FL

Presentations

11:00 AM : Updates to reference dosimetry protocols - B Muir, Presenting Author
11:18 AM : Impact of basic data - M Mitch, Presenting Author
11:36 AM : Dose to water vs. muscle: rationale - S Kry, Presenting Author
11:54 AM : Dose to water vs. muscle: practical implementation for different algorithms - V Feygelman, Presenting Author

TU-D-FS1-0 (Tuesday, August 1, 2017) 11:00 AM - 12:15 PM Room: Four Seasons 1


There have been recent and ongoing updates to clinical reference dosimetry protocols for the calibration of external beams. The addendum to the TG-51 protocol for reference dosimetry of photon beams was published in 2014 and the working group on the review and extension of beam quality conversion factors (WGTG51) is currently working on an update for electron beam dosimetry. An AAPM group has also been formed to address the long-standing question of whether clinical reference calibration should be done to water or to muscle.

This lecture will identify refinements to clinical reference dosimetry of MV photon beams as recommended in the addendum to TG-51 and discuss what the impact has been for clinical reference dosimetry. It will also present progress toward updating the TG-51 protocol for reference dosimetry for electron beams in terms of new recommendations for detector choice and updated beam quality conversion factors for accurate reference dosimetry. The impact of the recommendations in the recently-published ICRU Report on Key Data for Ionizing Radiation Dosimetry will also be discussed, where, for example, new stopping power values will affect calculated kQ factors and air-kerma based (i.e., TG-21) dose formalisms. Finally, recommendations will be presented on how a TG-51-based calibration in water relates to a calculation of dose to tissue in a patient, and when additional steps are required to make this link logically consistent.

Learning Objectives:
1. Understand the refinements to and the impact on reference dosimetry of photon beams recommended in the 2014 addendum to the TG-51 protocol.
2. Understand the changes being implemented in the upcoming addendum for electron beam dosimetry.
3. Understand the recommended changes to key data and the impacts on reference dosimetry.
4. Understand how a calibration in water relates to a dose calculation in tissue in the patient.
5. Know which planning systems inherently calculate dose to tissue and which do not and therefore require additional conversion.


Handouts


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