AbstractID: 8125 Title: The Need for New Approaches in Dosimetry and Calibration of Small
Beams for Radiotherapy
The Need for New Approaches in Dosimetry and Calibration of Small Beams For Radiotherapy
International Atomic Energy Agency (IAEA) Working Party on Small and Novel Field
Dosimetry in Cooperation with the AAPM Therapy Physics Committee
A working party has been formed by the International Atomic Energy Agency (IAEA) with
cooperation of the AAPM Therapy Physics Committee to examine the issues of dosimetry of
small fields and systems for which careful dosimetry techniques must be applied and which
cannot be calibrated according to calibration standards like the IAEA TRS-398 or the AAPM
TG-51 calibration protocols. This committee has documented the need for fine resolution when
determining the dose in small fields to overcome partial volume effects which can lead to a
severe underprediction of dose. There is a need to calibrate commercially available beams which
cannot open their field sizes to the required 10 cm x 10 cm as stipulated in official protocols. In
addition even those delivery systems which can be calibrated are often utilized, for example for
stereotactic radiosurgery or IMRT which is often composed of large numbers of small and
irregular fields. This talk will summarize the issues of small field dosimetry and calibration and
document the need for a change in approach. It is hoped that the committee can recommend
modifications and additions to standard protocols and measurement procedures to improve the
dosimetry of small fields.