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Dosimetric comparison of target-segmented plan versus conventional IMRT plan for post-mastectomy left-sided breast cancer patients / 中华放射医学与防护杂志
Chinese Journal of Radiological Medicine and Protection ; (12): 820-826, 2019.
Article in Chinese | WPRIM | ID: wpr-801033
ABSTRACT
Objective@#To compare the dosimetric differences among Target-Segmented Plan (TSP), Non-TSP, and conventional static 8-field intensity modulated radiation therapy (8F-IMRT) plan for post-mastectomy irradiation of left-sided breast cancer patients.@*Methods@#This study enrolled thirty consecutive breast cancer patients who underwent radical mastectomy and treated with post-op radiation in Department of Radiation Oncology, Renmin Hospital of Wuhan University from June 2017 to November 2018.The clinical target volume (CTV) included the ipsilateral chest wall, supra/infra-clavicular, high-risk partial axillary in high risk, and internal mammary nodes (IMN). The organs at risk (OARs) near the targets, including ipsilateral lung, heart, contralateral breast, ipsilateral humeral head and spinal cord, were contoured as well. The maximum distance of PTV′s tangent to the outermost side of the affected lung was more than 2 cm. Depending on the maximum distance, the patients were classified into three groups A(<3 cm), B(3~4 cm) and C(>4 cm), respectively. Three types of treatment plans (TSP, Non-TSP and 8F-IMRT) were created for each patient using the Eclipse treatment planning system with the same dose optimization objective . The dose-volume histograms were compared for the PTVs and OARs.@*Results@#All plans achieved the intended dose criteria.The D98% of TSP was lower than that of Non-TSP and 8F-IMRT (Z=-3.294, -3.266, P<0.05). However, the homogeneity index (HI) and conformal index (CI) of the three plans had no statistically significant difference among the three plans (P>0.05). Non-TSP required more Monitor Units (MUs)than the other two plans (Z=-3.04, -2.669, P<0.05). The Dmean of TSP was higher than that of 8F-IMRT (Z=-3.181, P<0.05). Compared with Non-TSP and 8F-IMRT plans, TSP significantly reduced V5 Gy, V10 Gy, V20 Gy and Dmeanof ipsilateral lung and heart in all patients (lung V5 Gy Z=-3.408, -3.408; V10 Gy Z=-3.408, -3.408; V20 Gy Z=-3.408, -3.124; Dmean Z=-3.408, -3.408, P<0.05; heart V5 Gy Z=-3.408, -3.408; V10 Gy Z=-3.408, -3.408; V20 Gy Z=-2.499, -3.067; Dmean Z=-3.408, -3.408, P<0.05). The Dmean of contralateral breast in Non-TSP was higher than that in TSP and 8F-IMRT (Z=-2.954, -2.215, P<0.05), and the Dmaxhas no significant difference in (P>0.05). There was no significant difference in spinal cord Dmax among the three plans, but the Dmean of humeral head in 8F-IMRT was higher than that in TSP and Non-TSP (Z=-3.01, -2.442, P<0.05). In the three groups, the mean amplitude of difference comparing Non-TSP and 8F-IMRT with TSP in ipsilateral lung(V5 Gy, V10 Gy, V20 Gy) and heart(V5 Gy, V10 Gy, Dmean) satisfied the relation D(N-T, A)<D(N-T, B) <D(N-T, C)和D(8F-T, A)<D(8F-T, B) <D(8F-T, C).@*Conclusions@#For post-mastectomy left-sided breast cancer patients, TSP is not only dosimetrically feasible as Non-TSP and 8F-IMRT treatment techniques, but also could effectively reduce the irradiation volume of the ipsilateral lung and heart in the low dose area with minimum adverse dosimetric impact on the treatment targets and other OARs.The advantage of TSP is more prominent with increasing curvature of the clinic target volume.

Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiological Medicine and Protection Year: 2019 Type: Article

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Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiological Medicine and Protection Year: 2019 Type: Article