Comparison of flattening filter and flattening filter free planning techniques in left breast radiotherapy

This thesis examines 50 patients who underwent breast conserving surgery after diagnosed with left breast cancer. All patients' medical conditions were similar and they were compatible with deep inspiration breath hold technique. Mean age of the patients were 54 and their ages were between 30 and 70. The patient group was dominantly middle aged which effected to use DIBH technique positively. 6 plans were created for each patient (by using 3 techniques). There are 300 plans in total. In this retrospective study, all 3DCRT, IMRT and VMAT plans were calculated using 6MV photon beams both FF and FFF modes and they were created on CT scans obtained by DIBH technique. The prime purpose of this thesis is to evaluate HI, CI, treatment time values and heart doses for each plan using FF and FFF beams. Showing how FF and FFF beams effect breast radiotherapy plans is aimed.FFF beams held the advantage of a shorter treament time as expected. DIBH technique is quite important to treat the patient in the shortest time as possible. FFF beams has the treatment time advantage in DIBH technique. FFF beamed 3DCRT plans had the shortest breath holding time for patients and they had better CI values. For HI values there were no statistically significant result for VMAT plans and FF beamed plans had more significant results for IMRT and 3DCRT plans. Irradiated volume of the heart was smaller and the treament time for the patien was shorter in the plans thanks to DIBH technique and FFF beams. FFF beamed plans were the most advantageous ones in every aspects. Late adverse effects of breast RT are rather important for patient groups whose survival rates are quite high. These adverse effects including coronery heart disease and death due to cardiac problems might be lowered by using FFF beams in breast RT. Keywords: Deep breath hold technique, flattened and unflattened beams, breast radiotherapy, treatment time for radiotherapy