Z Naimi1, R Moujahed2, H Neji3, J Yahyaoui4, A Hamdoun4, M Bohli2, L Kochbati2. 1. University of Tunis El Manar, Faculty of Medicine of Tunis, 1007 Tunis, Tunisia; Department of Radiation Oncology, Abderrahmen Mami Hospital, 2080 Ariana, Tunisia. Electronic address: zeinebnaimi89@gmail.com. 2. University of Tunis El Manar, Faculty of Medicine of Tunis, 1007 Tunis, Tunisia; Department of Radiation Oncology, Abderrahmen Mami Hospital, 2080 Ariana, Tunisia. 3. University of Tunis El Manar, Faculty of Medicine of Tunis, 1007 Tunis, Tunisia; Department of Radiology, Abderrahmen Mami Hospital, 2080 Ariana, Tunisia. 4. Department of Radiation Oncology, Abderrahmen Mami Hospital, 2080 Ariana, Tunisia.
Abstract
PURPOSE: This study aimed to assess radiation dose distribution to cardiac subvolumes in left-sided breast cancer radiotherapy (LBCRT) and to clarify whether the mean heart dose (MHD) reliably reflects cardiac substructures exposure. MATERIALS AND METHODS: Fifty women referred for adjuvant LBCRT were prospectively evaluated. All patients received 3D-conformal hypofractionated radiotherapy (40Gy delivered in 15 fractions of 2.67Gy±boost of 13.35Gy). Cardiac substructures were contoured using the F. Duane's cardiac atlas. Dose distribution to cardiac chambers, left main (LM), left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA)) was assessed. Dosimetric associations were analysed. RESULTS: The mean MHD was 3.08Gy (EQD2=3.67Gy). The mean Dmean/Dmax LAD was 11.45Gy (EQD2=13.64Gy)/29.5Gy (EQD2=35.15Gy). Low doses were delivered to LM, LCx, and RCA (Dmean≤1.3Gy). The left ventricle (LV) was the most exposed cardiac chamber with Dmean/Dmax of 4.78Gy/37Gy. The strongest correlation with MHD was found for Dmean LAD (r=0.81). For every 1Gy increase in MHD, Dmean LAD rose by 3.4Gy. However, the proportion of variance in Dmean LAD predictable from MHD was moderate (R2=0.65). For all other cardiac substructures, R2 values were<0.7. CONCLUSION: Our study showed high exposure of LAD and LV in LBCRT. With poor predictive value, MHD may underestimate doses to cardiac substructures. For optimal heart sparing radiotherapy, we recommend to consider LV and LAD as separate organ at risk.
PURPOSE: This study aimed to assess radiation dose distribution to cardiac subvolumes in left-sided breast cancer radiotherapy (LBCRT) and to clarify whether the mean heart dose (MHD) reliably reflects cardiac substructures exposure. MATERIALS AND METHODS: Fifty women referred for adjuvant LBCRT were prospectively evaluated. All patients received 3D-conformal hypofractionated radiotherapy (40Gy delivered in 15 fractions of 2.67Gy±boost of 13.35Gy). Cardiac substructures were contoured using the F. Duane's cardiac atlas. Dose distribution to cardiac chambers, left main (LM), left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA)) was assessed. Dosimetric associations were analysed. RESULTS: The mean MHD was 3.08Gy (EQD2=3.67Gy). The mean Dmean/Dmax LAD was 11.45Gy (EQD2=13.64Gy)/29.5Gy (EQD2=35.15Gy). Low doses were delivered to LM, LCx, and RCA (Dmean≤1.3Gy). The left ventricle (LV) was the most exposed cardiac chamber with Dmean/Dmax of 4.78Gy/37Gy. The strongest correlation with MHD was found for Dmean LAD (r=0.81). For every 1Gy increase in MHD, Dmean LAD rose by 3.4Gy. However, the proportion of variance in Dmean LAD predictable from MHD was moderate (R2=0.65). For all other cardiac substructures, R2 values were<0.7. CONCLUSION: Our study showed high exposure of LAD and LV in LBCRT. With poor predictive value, MHD may underestimate doses to cardiac substructures. For optimal heart sparing radiotherapy, we recommend to consider LV and LAD as separate organ at risk.
Authors: Francisco Acevedo; Teresa Ip; María Orellana; Gonzalo Martínez; Luigi Gabrielli; Marcelo Andia; Cecilia Besa; Mauricio P Pinto; Cesar Sánchez; Tomas Merino Journal: J Clin Med Date: 2022-07-04 Impact factor: 4.964