Dosimetric study of volumetric modulated arc therapy and tomo direct simultaneous integrated boost for patients receiving breast-conserving surgery for left breast cancer
10.3760/cma.j.cn371439-20220330-00075
- VernacularTitle:左侧乳腺癌保乳术后瘤床同步推量容积调强放疗与断层径照剂量学研究
- Author:
Biao ZHAO
1
;
Bo LI
;
Yupu ZHU
;
Lishuang MA
;
Meifang YUAN
;
Yi YANG
Author Information
1. 昆明医科大学第三附属医院 云南省肿瘤医院放射治疗科，昆明 650118
- Keywords:
Unilateral breast neoplasms;
Breast-conserving surgery;
Volumetric modulated arc therapy;
Tomo direct;
Dosimetry
- From:
Journal of International Oncology
2022;49(7):385-389
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the dosimetry difference between volumetric modulated arc therapy (VMAT) and tomo direct (TD) in tumor bed simultaneous push radiotherapy after left breast-conserving surgery, and to provide more dosimetry reference for clinic.Methods:A total of 22 patients with left breast cancer who underwent simultaneous quantitative radiotherapy after breast-conserving surgery were selected from the Department of Radiation Oncology, Yunnan Cancer Hospital from December 2018 to June 2020. The localized CT images and target organs at risk and other structural data were collected. Two radiotherapy plans, VMAT and TD, were designed for the same patient, and the dosimetry differences of target areas and organs at risk were compared and analyzed between the two groups.Results:In terms of target dosimetry, there were statistically significant differences in the D 2% [ (59.99±0.19) Gy vs. (59.55±0.51) Gy, t=4.09, P<0.001], D 98% [ (57.19±0.08) Gy vs. (57.46±0.22) Gy, t=-5.10, P<0.001], conformal index (CI) (0.76±0.05 vs. 0.58±0.13, t=8.19, P<0.001) and homogeneity index (HI) (0.05±0.00 vs. 0.04±0.01, t=4.89, P<0.001) of the planning gross tumor volume (PGTV) between VMAT and TD plans. However, there was no statistically significant difference in the D 50% [ (58.73±0.10) Gy vs. (58.73±0.24) Gy, t=-0.03, P=0.974]. There were statistically significant differences in the D 50% [ (52.21±0.33) Gy vs. (53.00±0.72) Gy, t=-4.81, P<0.001], D 98% [ (48.44±0.43) Gy vs. (49.09±0.21) Gy, t=-6.80, P<0.001], CI (0.83±0.06 vs. 0.67±0.06, t=10.52, P<0.001) and HI (0.20±0.01 vs. 0.19±0.01, t=8.75, P<0.001) of the planned target volume (PTV) between the two plans. However, there was no statistically significant difference in the D 2% [ (59.01±0.45) Gy vs. (59.00±0.48) Gy, t=0.22, P=0.830]. In terms of organs at risk, there were statistically significant differences in the V 20 [ (18.81±2.86) % vs. (22.03±1.91) %, t=-5.36, P<0.001] and D mean [ (11.66±1.32) Gy vs. (12.85±1.46) Gy, t=-4.10, P=0.007] of left lung, V 5 [ (5.70±2.90) % vs. (0.30±0.13) %, t=16.44, P<0.001] and D mean [ (2.45±0.29) Gy vs. (0.43±0.14) Gy, t=9.09, P<0.001] of right lung, D mean [ (3.22±0.72) Gy vs. (1.69±0.80) Gy, t=5.41, P<0.001] of right breast, D 2% [ (5.37±1.97) Gy vs. (0.46±0.09) Gy, t=11.75, P<0.001] of cord between VMAT and TD plans. There were no significant differences in the V 5 of left lung [ (53.00±5.99) % vs. (50.00±7.69) %, t=1.91, P=0.061], V 5 of right breast [ (11.51±4.60) % vs. (8.06±3.49) %, t=1.59, P=0.120], V 30 [ (1.49±0.69) % vs. (1.51±0.71) %, t=-0.06, P=0.952] and D mean [ (3.99±0.97) Gy vs. (3.90±1.03) Gy, t=0.56, P=0.581] of heart between the two plans. Conclusion:TD and VMAT can meet the clinical dosimetry requirements for patients with left breast cancer after breast-conserving surgery. However, the two techniques have their own characteristics. VMAT has better conformity and TD has better uniformity. TD is significantly better than VMAT in protecting the right lung, right breast and spinal cord of healthy organs at risk. VMAT is better in protecting the left lung. Both VMAT and TD basically achieve the same protection for heart.
