Seminar

Medical Physics Seminar – Monday, April 18, 2022

Dosimetry of small static photon fields: Challenges and solutions

View Flyer

speaker

Saiful Huq, PhD, FAAPM, FInstP
Professor and Director UPMC Hillman Cancer Center and University of Pittsburgh School of Medicine, Pittsburgh, PA

Intensity modulated radiotherapy, Stereotactic radiosurgery and stereotactic body radiotherapy routinely use radiation beams of small field sizes to treat small tumors. The delivery of such treatments are routinely performed using specialized dedicated machines such as CyberKnife, GammaKnife, Tomotherapy as well as accelerators equipped with high-resolution multileaf collimators. The International Atomic Energy Agency (IAEA) and the American Association of Physicists in Medicine have jointly published a Code of Practice (CoP), TRS483, that provides recommendations for reference dosimetry using ionization chambers in machines that cannot establish a conventional 10 cm x 10 cm reference field. The formalism for reference dosimetry is based on the work of Alfonso et al., Med. Phys. 35 (2008). The CoP also provides recommendations for measurements of field output factors in small fields using high-resolution detectors such as diodes, diamond, and radiochromic film. Experimentally determined and/or Monte Carlo calculated correction factors for recommended ionization chambers are given for reference dosimetry in non-standard machine specific reference (msr) fields. The CoP also provides data for correction factors for high-resolution detectors such as diodes, diamond detectors etc for the determination of field output factors. These data are based on a vetted survey of literature data combined with Monte Carlo calculations.

In this presentation I will provide a review of the recommendations given in TRS483 Code of Practice for reference dosimetry performed in machine-specific-reference fields and relative dosimetry performed in static small fields in high energy photon beams.

Location: Webex

Time: 4:00PM-5:00PM