Effect of Secondary Induced Radiation: An Observational Study

Measurable radiation level near the treatment head of medical electron linear accelerator (LINAC) and in its surrounding is observed due to induced activity, exposing therapy staff to unwanted radiation dose. A study has been done to reduce the exposure to lower level.2D, 3DCRT and IMRT pelvic irradiation were studied which was planned with 15 MV photon beam and also systematic study was carried out to quantify the radiation levels near LINAC head for planned beam delivery of 200, 400, 600, 800, 1000, 1500 Monitor Units for field sizes 10 x 10 cm2, 20 x 20 cm2, 30 x 30 cm2, 40 x 40 cm2. All measurements were carried out to quantify the radiation level near LINAC head. The dose received by radiation therapists was estimated. The highest personal dose received by radiation therapist was estimated at 5.2 mSv/y due to IMRT pelvic irradiation. The potential hazard to staff from induced activity in the use of high energy photon beams was considered to be very low and no specific actions are considered necessary.