Medical Physics Seminar – Monday, December 12, 2011
"Measurements and Calculations of Doses Outside the Treatment Volume External Beam Radiation Therapy"
Bryan Bednarz, Ph.D.
Assistant Professor, Department of Medical Physics, UW-School of Medicine & Public Health, Madison, WI USA
Location: 1335 (HSLC) Health Sciences Learning Center, 750 Highland Avenue, Madison, WI 53705
This seminar will provide an overview of the forthcoming TG-158 report, Measurements and calculations of doses outside the treatment volume from External Beam Radiation Therapy”. The current task group is presented to compliment upcoming reports of the NCRP and ICRP. This task group report will document how to perform measurements and calculations of organ doses for outside the treated volume irradiations from various existing and emerging treatment modalities and procedures. It is conceivable that more accurate dosimetry will improve patient risk assessment, understanding of dose response coefficients, treatment planning, as well as design of the radiation delivery machines. This report will also highlight the broader basis for concern of non-target doses that is relevant in clinical care (e.g., including non-somatic effects), and will also offer techniques to minimize non-target doses.
This report will specifically:
1. Provide a rough estimate of doses associated with different treatment approaches in clinical practice
2. Discuss the uses of dosimeters and phantoms for measuring photon, electron, and neutron exposures,
3. Discuss the uses of calculational techniques (including Monte Carlo) for dosimetric evaluations,
4. Highlight major concerns with non-target radiation, and
5. Highlight techniques that may be considered for reducing non-target doses
The focus of this report will be doses from external treatment beams and will consider relatively new modalities such as IMRT, tomotherapy, SBRT, protons, and carbon-ion therapy. Brachytherapy doses are not covered in this report. Imaging modalities such as PET, CT, or CT/PET that are used for treatment planning, as well as online image-guiding modalities, such as on-board imaging and megavoltage cone beam computed tomography (MV-CBCT), will only be briefly mentioned.