Assessment of the Effect of Breathing Movements on the Skin Dose by Comparison of TLD Measurements and Plan Data in Breast Cancer Radiotherapy
Özet
Breast cancer is the most common type of cancer in women. One out of every four women suffers from breast cancer in the world. İt is important for receiving adequate skin dose in breast cancer radiotherapy. The detailed information of dose in various depths of skin has a critical importance to determine new treatment techniques. If the skin dose homogeneity is not achieved, the risk of recurrence of disease is increased. Therefore, the homogeneity of dose distribution should be provided on the surface as it is in other parts of the breast.
The aim of this study is to investigate the effect of respiratory movement and using the bolus on skin dose in breast cancer patients treated with helical tomotherapy. TLDs were placed on both the surface of the Alderson RANDO phantom's breast in eight points and on the projections of each points which is about 5 mm deep. A mechanism was used, which can be adjusted to the different frequency and amplitude values to simulate for measurements. The measurements were performed statically and dynamically (frequency=0.3 Hz, amplitude=5mm). Each measurement was repeated with and without bolus. The mean dose values were measured by using TLDs and bolus during respiratory at the surface and at 5 mm depth. The measured TLDs and calculated doses of TPS were compared, investigating the change of skin dose. The data were evaluated using the SPSS 20.0 statistical analysis program. According to the results, it is concluded that the respiratory movement is not a significant effect on the skin dose and it is not necessary to use the bolus. Besides, when TPS and TLD results were compared to each other; it is seen that, the estimation of skin dose of, TPS calculations was higher than TLDs measurements. This is clinically accepted. The results are in good agreement with literature values.