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SU‐E‐T‐72: Dosimetric Effects of Vaccum Bag, Body Positioning System and Accelerator Treatment Couch for Lung Cancer Radiotherapy
Author(s) -
Lin X,
Yin Y,
Sun T,
Zhang G,
Liu T,
Bai T
Publication year - 2011
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3612023
Subject(s) - medicine , nuclear medicine , radiation therapy , dosimetry , lung cancer , radiation treatment planning , lung , spinal cord , treatment of lung cancer , radiology , psychiatry
Purpose: To study the effect of vaccum bag, body positioning system and accelerator treatment couch on the dosimetry of lung cancer radiotherapy. Methods: Ten patients with central lung cancer treated with radiotherapywere enrolled in this study, using Varian Eclipse treatment planning system delineated three different regions of dose calculation on CT images of each patient. Only the contours of patientsˈ surface were delineated on the first group CT images; contours of vaccum bag and body positioning system were added on the second group CT images;then contours of accelerator treatment couch were added on the third group CT images. Same plans were designed on each patientˈs three group CT images respectively, and named plan1, plan2, plan3. The dose of target and organs at risk and the number of MUs were analyzed. Results: The maximum, minimum, mean dose to target and the target volume receiving prescription dose have no statistically significant differences among three group plans.No statistically significant differences were observed in the maximum dose of spinal cord between plan1 and the other plans. Compared with plan2, the maximum dose of spinal cord increased 3% in plan3(p=0.008). No statistically significant differences were observed in the mean dose of heart and ipsilateral lung among three plans.For the volume receiving more than 20 Gy (V20) of ipsilateral lung,plan3 and plan1 showed the highest and lowest values respectively, significant differences were observed between any two plans. Compare to plan1, the plan2 and plan3 statistically significantly increased the maximum, minimum and mean dose of subcutaneous 5mm and 10mm regions of the patientsˈ back, and the plan3 performed more obviously. Compared to plan1, the MUs of plan2 and plan3 increased 2% and 5% respectively(p<0.005). Conclusions: Vaccum bag, body positioning system and accelerator treatment couch would affect the dose of radiotherapy plans, we should consider these factors when designing plans, and correct the dose if necessary.