Program Information
Neutron Particles Contamination InLinear Accelerator During Total Body Irradiation Treatment
S Ahmed1*, K Mariam2 , A Hussain3 , A Tariq4 , (1) Sinsh Institute of Urology and Transplantation (2) Aga Khan university Hospital, Karachi, sindh, (3) Tom Baker Cancer Centre (TBCC), Calgary, Canada, (4) NED university of engineering and technology, Karachi, sindh
Presentations
SU-I-GPD-E-5 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: High energy linear accelerators when driven above 10MV, unwanted neutron produced and its measurement is very challenging due to low percentage. For the case of total body irradiation (TBI) treatment, usually the number of MU’s are about 2000 to2500 per filed per fraction. Therefore, neutron equivalent dose (NED) measurements should perform for higher energy photon. The purpose of the study is to measure effect of different parameters on the production neutrons inside and outside of the treatment room during TBI treatment.
Methods: Two standard TBI setup simulated to find out NED for 10MV and 18MV beam using water equivalent phantom with Ludlum Model 42-31H Neutron Detector. First set of observation obtained without phantom by placing the detector on couch, further readings obtained with 3cm increment in lateral directions and up and down direction from isocenter, entire process repeated with phantom which simulating the laterals and AP/PA treatment delivery.NED also find out as a function of field size. Scattered neutron doses along the phantom and along the passage of the maze are also measured. For radiation protection of staff and general worker, measurements also performed outside the bunker including controlled and supervise area.
Results: Results shows, NED values measure with phantom are high at head level and then gradually decrees. For without phantom, are low at the mid-level and high at the edges for AP/PA but different for the case of lateral direction.The scatter NED values along phantom is less but outside the field is comparatively higher. Along the maze area at the entrance point the values approximately zero and then gradually increases.
Conclusion: Study suggested, TBI treatments done with 10MV may have less neutron contamination than 18MV, less contamination lead to less scattered, which eventually leads to less neutron absorb dose to patient as well as staff.
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