Radiotherapy
Study on dose accumulation in IMRT for left breast cancer patients after radical mastectomy
Su Ming, Yin Yong, Gong Guanzhong, Ren Jianxin, Yao Xinsen, Qiu Xiaoping
Published 2019-12-25
Cite as Chin J Radiol Med Prot, 2019, 39(12): 910-915. DOI: 10.3760/cma.j.issn.0254-5098.2019.12.006
Abstract
ObjectiveTo investigate the changes of accumulated dose in target area and organs at risk (OARs) for radiotherapy of left breast cancer by deformable and rigid image registration.
MethodsA total of 16 left breast cancer patients treated with 6 MV X-ray IMRT were analyzed retrospectively. All targets included the lymph node drainage area and the chest wall. All patients underwent simulation of the primary positioning and repositioning to obtain CT images. Primary and secondary treatment plans were developed using primary positioning CT (CT1) and repositioning CT (CT2), denoted as Plan1 and Plan2 respectively. The dose distribution of Plan2 was mapped to CT1 with rigid and deformable registration from CT2 to CT1 and then added to the dose distribution of Plan1 to obtain Plan-rigid and Plan-deform, respectively. The dosimetric differences between targets and the OARs of the four plans were compared.
ResultsThe CTV volume on CT2 was reduced by 6.64% from that on CT1. The homogeneity index (HI) increased by 23.05% after deformation-based accumulation. The Dice similarity coefficients (DSCs) of the heart, left lung and right lung were lower than those before deformable registration (0.94±0.01 vs. 0.89±0.05, 0.96±0.01 vs. 0.91±0.03, and 0.96±0.01 vs. 0.92±0.03, respectively), and the differences were statistically significant (Z=-3.208, -3.533, -3.535, P<0.05). There were no significant differences in dose-volume indices of heart and left lung between Plan1 with other plans(P>0.05), while the dose-volume indices in Plan-rigid were higher than that in Plan-deform.
ConclusionsRigid registration is recommended in patients undergoing radical resection of left breast cancer with little change in the volume and dose-volume index of the target area and organs at risk. The dose-volume index of the initial intensity modulation plan can basically reflect the dose-volume statistics of both lungs and heart.
Key words:
Breast cancer; Dose addition; Deformation registration; Dose assessment; IMRT
Contributor Information
Su Ming
School of Nuclear Science and Technology, University of South China, Hengyang 421001, China(Su Ming is working in the Radiation Physics Department of Shandong Cancer Hospital Affiliated to Shandong University, Jinan 250117, China)
Yin Yong
Department of Radiation Oncology Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China
Gong Guanzhong
Department of Radiation Oncology Physics, Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan 250117, China
Ren Jianxin
School of Physics and Technology, Wuhan University, Wuhan 430072, China
Yao Xinsen
School of Nuclear Science and Technology, University of South China, Hengyang 421001, China
Qiu Xiaoping
School of Nuclear Science and Technology, University of South China, Hengyang 421001, China
