Abstract
Aim: Dosimetric analysis of three different Radiotherapy techniques in patients with Breast Cancer and their impact on OAR’s. Materials and Methods: 12 patients of Carcinoma Breast who received breast radiotherapy were selected for analysis. Computed tomography (CT) simulation image data sets were retrieved. Planning target Volume (PTV), heart and ipsilateral lung were contoured for planning and analysis of doses. Three different plans using conventional bi-tangential fields were prepared, Plan 1 with SAD full beam with wedge (SAD-FBW), Plan 2 with SSD half beam with wedge (SSD-HBW) and plan 3 with SSD half beam without wedge techniques (SSD-HBO) in CMS Xio TPS. Statistical analysis was done using SPSS version 16.0. Results: The PTV coverage was significantly better in SAD-FBW techniques when compared with the other two techniques i.e. SSD-HBW (mean = 92.33, SD = 4.69, p = 0.005) and SSD-HBO (mean = 75.05, SD = 11.92, p = 0.002). The mean heart doses were significantly better in SAD-FBW compared to SSD-HBW (mean = 3.75, SD = 2.27, p = 0.017) but in SSD-HBO technique mean heart doses were better than SAD-FBW technique (mean = 3.27, SD = 1.94, p = 0.004). Similarly, the left lung V20 values were significantly better in SSD-HBO technique than SAD-FBW technique (mean = 11.75, SD = 4.34, p = 0.004) but there was statistically insignificant difference between the SAD-FBW and SSD-HBW techniques. The treatment monitor units were significantly less in SAD-FBW compared to SSD-HBW but SSD-HBO has less MU compared to SAD-FBW technique. Conclusion: SAD Full Beam with wedge technique is practically better than SSD Half Beam technique with or without wedge without compromising PTV coverage considering other dosimetric parameters. We also recommend that centers treating patient with half beam SSD techniques should shift immediately to SAD techniques.
Highlights
Breast cancer is the most common female cancer in the India with an ASR (Age Standardized Rate) of 25.8 as per Globocan 2012 [1]
The most recent analysis of Early Breast Cancer Trialists Collaborative Group (EBCTCG) included individual patient data from 45,000 women in 86 randomized trials. Provisional results from this overview show that radiotherapy after breast surgery reduced the 5 year local recurrence by 15.7% and the 15 year breast cancer mortality by 4.2% and that post mastectomy radiotherapy for node-positive disease reduced the 5 year local recurrence by 19.3% and the 20 year breast cancer mortality by 6.3% [3] [4]
This was shown in our study that the Planning target Volume (PTV) coverage is best when SAD full beam with wedge (SAD-FBW) technique is used compared to use of half beam block technique (Table 1) which is still a common practice in many centers across India
Summary
Breast cancer is the most common female cancer in the India with an ASR (Age Standardized Rate) of 25.8 as per Globocan 2012 [1]. The most recent analysis of Early Breast Cancer Trialists Collaborative Group (EBCTCG) included individual patient data from 45,000 women in 86 randomized trials. Provisional results from this overview show that radiotherapy after breast surgery reduced the 5 year local recurrence by 15.7% and the 15 year breast cancer mortality by 4.2% and that post mastectomy radiotherapy for node-positive disease reduced the 5 year local recurrence by 19.3% and the 20 year breast cancer mortality by 6.3% [3] [4]. One of the aims in modern radiotherapy is to avoid early and late side effects associated with treatment This can be achieved by steep dose gradients between the target volume and the surrounding normal tissues. The main concern of IMRT is increase in healthy soft tissue dose which might cause an increased risk of late secondary malignancy [6]
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