Tertiary collimator system for stereotactic radiosurgery with linear accelerator

english

1998

volume 32, issue 1

Onkološki inštitut Ljubljana

In the last decade, stereotactic radiosurgery (SRS) with linear accelerator (linac) has become an important irradiation technique for a variety of malignant and benign intracranial lesions. Although there exist some other radiosurgery techniques, linac based SRS meets the requirements needed for SRSwith low cost modifications. On of the most important additional parts of the equipment is tertiary collimator system which can be attached onto the linac head. We designed and built such system that can be easily fixed onto linac PHILIPS SL - 75/5 with 5 MV photon energy. In our department, we alreadyuse this linac for conventional radiation therapy. Our tertiary collimator system meets all the requirements important for this special modality of radiation therapy. It allows fine centering of the system and has ten various collimators with divergent circular openings having a nominal field diameter ranging from 1.0 cm to 4.0 cm at the isocenter. The accuracy ofthe system was checked by exposing x - ray films at various gantry positions, and recording misalignment of the beams. The width of penumbra was determined using two different dosimetry techniques (film dosimetry and diode measurements).

10.11.2023