Effect of the Cavity of Bolus and Skin on Radiotherapy Dose after Modified Radical Mastectomy
TANG Jingyi1, LI Jinkai2, WANG Peipei2, LI Caihong2, CHANG Zhigang2,
GU Xiaohuan2, HU Xiaowei2, LI Hualing2, SUN Xinchen2
1. School of First Clinical Medical, Nanjing Medical University, Nanjing Jiangsu 210000, China; 2. Department of Radiotherapy,
Jiangsu Province Hospital/The First Affiliated Hospital with Nanjing Medical University, Nanjing Jiangsu 210029, China
Abstract：Objective To study the dosimetric effect of the cavity of the bolus and skin on the target area and organs at risk during
radiotherapy after modified radical mastectomy. Methods CT localization images of 20 patients with left side radical mastectomy
were selected. The skin contour was expanded outward by 2, 5 and 10 mm, respectively, and the CT value of the enlarged part was
set as 0 to simulate the cavity gap between the bolus and skin. Based on the addition of 1 cm virtual compensation film on the chest
wall of the target side, four kinds of volume rotation intensity modulation plans were developed according to the space size: no
cavity group, 2 mm cavity group, 5 mm cavity group, 10 mm cavity group and the original group was selected as the control group
to evaluate dose differences among different groups in the target area and superficial skin, heart, affected lung and affected humeral
head. Results All the target dosimetric indexes of the five groups met the prescription dose requirements, there was statistically
significant difference of the planning target volume (PTV50) between the no cavity group, 2 mm cavity group, 5 mm cavity group
and the control group (P<0.05). In addition, with the increase of the cavity, PTV50 decreased. There was statistically significant
difference of the conformity index between the no cavity group, 2 mm cavity group, 5 mm cavity group, 10 mm cavity group and
the control group (P<0.05). There was no statistically significant difference of the heterogeneity index between the no cavity group, 2 mm
cavity group, 5 mm cavity group, 10 mm cavity group and the control group (P>0.05). For superficial skin, there was statistically
significant difference in Dmin, Dmax and Dmean doses between the 2 mm cavity group, 5 mm cavity group, 10 mm cavity group and the
control group (P<0.05), and the Dmean dose of superficial skin showed an increasing trend with the increase of cavity. The influence of
cavity on the affected lung, humeral head and heart was relatively small, and the difference was not statistically significant (P>0.05).
Conclusion The cavity can affect the target area and superficial skin dose, so the cavity should be reduced as much as possible
during radiotherapy placement.
唐静宜1，李金凯2，王沛沛2，李彩虹2，昌志刚2，顾宵寰2，胡晓伟2，李华玲2，孙新臣2. 补偿膜与皮肤间空腔对乳腺癌改良根治术后放疗剂量的影响[J]. 中国医疗设备, 2023, 38(8): 16-20.
TANG Jingyi1, LI Jinkai2, WANG Peipei2, LI Caihong2, CHANG Zhigang2,
GU Xiaohuan2, HU Xiaowei2, LI Hualing2, SUN Xinchen2. Effect of the Cavity of Bolus and Skin on Radiotherapy Dose after Modified Radical Mastectomy. China Medical Devices, 2023, 38(8): 16-20.
