Purpose: To explore the use of custom compensators for modulated electron radiotherapy (MERT). Method and Materials: Several simple compensators, made of acrylic and paraffin, were placed in the 10×10 cm2 electron applicator of a Varian 2100C linear accelerator. Kodak EDR2 film was placed at various depths in a solid water phantom located at a SSD of 100 cm. Simulated treatments were delivered using either a single energy or multiple energies to demonstrate the effect of the compensator on the resulting dose distribution. Dose distributions for the compensator‐shaped fields were obtained from film measurements and compared to distributions measured for open 10 × 10 cm2 fields. Results: The use of compensators with multiple electron energies resulted in complex dose distributions that cannot be formed easily with standard electron cutouts. A relatively smooth gradient was observed at locations where compensator thickness changed rapidly. It was observed that the compensator‐ shaped fields exhibited more gradual dose drop‐off at the edges of the field. The penumbra for the compensator‐shaped fields was somewhat larger than that for the open single‐energy fields. Conclusion: The use of custom compensators for modulation of electron beam energy and intensity is a promising technique that may be of clinical use in MERT treatments.
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging