Introduction Post-mastectomy radiation in left-sided breast cancer in women continues to pose a significant risk to the underlying lungs and heart. This study analyzed the difference in planning target volume (PTV) coverage and dose to the organs at risk (OAR) by using three different planning methods for the same patient - three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and volumetric-modulated arc therapy (VMAT). Material and methods Thirty-five left-sided breast cancer patients’ post-mastectomy were included in this study, and three different plans for adjuvant radiation were created using 3D-CRT, IMRT, and VMAT. The prescribed dose was 50Gy in 25 fractions. Kruskal-Wallis analysis of variance (ANOVA) was done, followed by a pairwise t-test to establish a hierarchy of plan quality and dosimetric benefits. The plans were compared with PTV 95 , homogeneity index (HI), conformity index (CI), hotspot (V 107% ), left lung V 20Gy , mean lung dose, heart V 25Gy , mean heart dose, and integral dose (ID) to the body. Results Both VMAT and IMRT led to improved PTV 95% coverage (95.63±1.82%, p=0.000 in VMAT; 93.70±2.16 %, p=0.000; 81.40±6.27% in 3D-CRT arm) and improved CI (0.91±0.06 in IMRT [p<0.05] and 0.96±0.02 for VMAT plans [p<0.05]) as compared to 3D-CRT (0.66±0.11), which was statistically significant on pairwise analysis. In contrast, the difference in HI and reduction in hotspots were not significantly different. Left lung V 20 was statistically very different between the three arms with the highest values in IMRT (36.64±4.45) followed by 3D-CRT (34.80±2.24) and the most negligible value in VMAT (33.03±4.20). Mean lung dose was also statistically different between the three arms. There was a statistically significant difference in mean heart dose between the three arms on pairwise analysis. Both the inverse planning methods led to a statistically significant increase in low dose volume (V 5 and V 10 ) of the ipsilateral lung, opposite lung, and heart, and increased ID to the body excluding the PTV. Conclusion While both the inverse planning modalities led to increased coverage, better CI, and better HI and decreased high dose volumes in OARs, there was increased low volume irradiation of heart, lungs, and body with VMAT faring marginally better than IMRT in coverage and decreasing lung irradiation with comparable heart irradiation.

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IntroductionIntracavitary brachytherapy (ICBT) is an integral component in the management of locally advanced cervical cancer. Spinal anaesthesia is the preferred mode of pain management during brachytherapy procedures. In high volume, resource constraint settings, it is difficult to provide spinal anaesthesia to all patients. This study attempts dosimetric comparison of high-dose-rate ICBT with spinal anaesthesia to that under conscious sedation to find out whether brachytherapy under conscious sedation is comparable with spinal anaesthesia. MethodsRetrospective data of total of 56 cervical cancer patients who received ICBT after completion of external beam radiotherapy (EBRT) were collected. Among these 56 patients, 28 patients received brachytherapy under spinal anaesthesia (SA group) and the rest under conscious sedation (CS group). Brachytherapy dose was 7 Gray per fraction weekly for three weeks. Thus, 84 brachytherapy plans of each group were analysed with respect to doses received by points A, B, P and Organs at Risk. ResultsThe mean doses received by points A, B and P were comparable in SA and CS groups (p-value >0.05). Similarly, the mean doses received by Organs at Risk (rectum, urinary bladder, and sigmoid colon) were also comparable in both the groups (p-value>0.05). ConclusionICBT under CS is dosimetrically non-inferior to SA, which makes it an alternative option.

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