Evaluation of surface dose outside the treatment area for five breast cancer irradiation modalities using thermo-luminescent dosimeters

International Journal of Cancer Therapy and Oncology

Theodora Leventouri¹  Suraj Prasad Khanal¹  Rashmi K Benda²  Zoubir Ouhib² 

[1] Department of Physics, Medical Physics Program, Florida Atlantic University, Boca Raton, Florida;Department of Radiation Oncology, Lynn Cancer Institute, Boca Raton Regional Hospital, Boca Raton, Florida;

关键词: TLDs;    Absorbed Dose;    Deterministic Effect;    Boost;    Induced Cancer;   

DOI  :  10.14319/ijcto.0301.17

来源: DOAJ

【 摘 要 】

Purpose: To measure and compare the surface dose outside the treatment area at six different points of interest (POIs) for five different breast cancer radiation treatment modalities by using thermo-luminescent dosimeters (TLDs). This experiment will evaluate the magnitude of the dose due to scatter and leakage radiation at different areas outside the target on a patient that could potentially lead, in the long term, to radiation induced secondary malignancies.

Methods: TLD-100 were calibrated according to the University of Wisconsin Radiation Calibration Laboratory protocol and then used for dose measurements at selected POIs namely sternum, lower abdomen, contralateral breast, thyroid, shoulder, and eye. Twenty five breast cancer patients and the following modalities were included in this study: Strut-adjusted volume implant (SAVI), mammosite multi-lumen (ML), Accuboost, electron boost and photon boost. The surface doses in all patients were measured in a single fraction. The delivered target doses were normalized to 200 cGy. Finally, breast quadrant analysis was performed.

Results: The maximum average dose for each POI was as follows: Sternum 6.51 cGy (SD 2.93), lower abdomen 4.50 cGy (SD 2.63), contralateral breast 8.52 cGy (SD 3.86), thyroid 5.50 cGy (SD 2.75), shoulder 5.58 cGy (SD 2.77), and eye 2.65 cGy (SD 0.68). The highest POI dose of 15.84 cGy was found in contralateral breast.

Conclusion: The measured surface dose at each POI varies with the modality of treatment. The surface doses show a strong correlation to the tumor bed location in the breast quadrant. The SAVI, electron boost, and photon boost modalities had delivered smaller surface dose at POIs than the Accuboost and Mammosite ML modalities. While the measured doses fall within the low range, its significance in producing second malignancies would require a large cohort of patients and a longer follow up.

【 授权许可】

Unknown