Measurement of ipsilateral lung and heart dose in radiotherapy of left sided mastectomy patients in common different clinical techniques: A phantom study

Abstract

Background: The aim of this study was to compare the radiation dose to ipsilateral lung and heart for different radiotherapy (RT) techniques including; two tangential photon beams, electron therapy and combined photon-electron. Materials and Methods: Treatment planning of the mentioned techniques on the CT images of a chest phantom was done using treatment planning system (TiGRT, Lina Tech, China). According to the plans, the phantom was irradiated with 6 MV photon and 10 MeV electron beams of Siemens Primus linac. Radiation dose was also measured using LiF Thermo Luminescence Dosimeter (TLD) which was placed inside 3 mm depth holes of ipsilateral lung and heart on the phantom. Results: The mean (+/- SD) radiation dose to the ipsilateral lung of the combined photon-electron was 66.12 +/- 5.16 of prescribed dose. Whereas for the heart, it was 64.05 +/- 2.62. Mean (+/- SD) dose of ipsilateral lung and heart for electron irradiation was 54.51 +/- 3.88 and 34.21 +/- 3.41, respectively. The mean (+/- SD) radiation dose to ipsilateral lung and heart of the tangential was 50.73 +/- 3.01 and 31.36 +/- 3.13, respectively. The mean (+/- SD) radiation dose to the chest wall-lung interface for electron therapy (72.44 +/- 2.01 ) was significantly different in comparison with tangential (65.23 +/- 4.20; p = 0.045) and combined photon-electron (68.14 +/- 3.53 ; p = 0.032). Conclusion: Tangential beams is more suitable for treating mastectomy patients compared to the other techniques such as electron therapy and combined photon-electron, due to lower radiation dose to patient's ipsilateral lung and heart.