Dosimetric impact of target volume anatomical parameters on radiotherapy after right-sided breast-conserving surgery

Objective To investigate the dosimetric effects of target volume Anatomical Parameters on organ at risk (OAR) following breast-conserving surgery and subsequent radiotherapy in patients with right-sided breast cancer. Methods A retrospective study was conducted on 33 patients who underwent post-breast-conserving surgery radiotherapy. The transverse diameter (TD), oblique diameter (OD), and the ratio of transverse diameter to oblique diameter (TOR) were measured at the nipple-center plane for all patients. Bivariate Pearson correlation analysis was used to examine the effects of TD, OD, and TOR on V 20Gy , V 5Gy , D mean of the affected lung; D mean and V 5Gy of heart; D mean of the right coronary artery (RCA); D mean of the left anterior descending artery (LAD); V 5Gy of the contralateral lung; and D mean of the contralateral breast. Results OD and TD showed significant correlations with V 20Gy , V 5Gy , and D mean of the affected lung ( 0.5 < R < 0.7, P < 0.01 ); The TD was significantly correlated with Heart_D mean ( R = 0.58, P < 0.01 ), strongly correlated with RCA_D mean ( R = 0.45, P < 0.01 ), and strongly correlated with LAD_D mean ( R = 0.42, P < 0.05 ); The TOR was significantly correlated with Heart_D mean ( R = 0.47, P < 0.01 ), strongly correlated with LAD_D mean ( R = 0.47, P < 0.01 ). Conclusion Exploratory observational thresholds from our cohort: target volume with TD >8.00 cm or OD >19.56 cm indicates higher lung dose risk; TD >8.00 cm or TOR >0.47 indicates higher cardiac dose risk. These thresholds were not optimized by ROC analysis and cannot be directly used for clinical risk stratification; prospective validation is needed. Clinical planning should minimize heart and lung radiation.