The Effects Of Cardio-pulmonary Individualized Dose Consideration On The Chest Radiotherapy Treatment Plan Design

Individual dose volume effect target does not get enough attention or get totally ignored in the chest tumor treatment planning because physicists tend to focus on the physical indexes,such as target dose uniformity and conformity.Under the influence of personalized effect and verification of patient’s physical conditions,function ability of different organs vary.To maximize patient’s radiation treatment outcome,differences in patient’s organ functions and dose volume effect need to be taken into account in the treatment planning process with compromises of general indexes.The purposes of this study is to understand the personalized treatment planning idea with the consideration of target volume,through the choices of optimal beam angles which are based on patient’s specific cardio-pulmonary function to achieve the personalized treatment planning concept,furthermore,to obtain the clinical outcome.Through the IMRT plan design without consideration of the patient individual differences and the free beam angles plan design with consideration of patients’ individual differences and volume effect,we explored the merits and differences of treatment plan design for clinical analysis.This paper compared dosimetry of 55 chest wall cancer patient cases in planning design,including 39 lung cancer cases,16 esophageal cancer cases.Wherein the upper lobe lung cancer includes 5 cases,8 cases of right middle lung cancer,4 cases of the right lung lower lobe cancer,10 cases of left lung upper lobe,the left lung lower lobe in 12 cases,6 cases of upper esophageal cancer,6 cases in the middle esophagus cancer,4 cases of the lower esophageal cancer.Planning design ideas are: Plan A is the original plan.Plan B is the plan with the first priority of lung tissue dose volume.And it is based on the patient’s clinical situation of lung function and is consciously to seek the possibility of reducing the patient dose volume of lung tissue.Plan C is the plan with dose volume of heart as its first priority.And it is to seek the possibility of reducing a patient’s dose volume of heart based on cardiac functions according to the conscious patient’s clinical situation.The main idea of the planning was based on the plan original design,Plan A,then by changing the beam angles and the parameter indexes to strengthen that heart and lung constrains used in IMRT optimization,to achieve the goal of lower lung or heart tissue dose volume.Plan A,Plan B and Plan C give the prescribed dose 60 Gy for PTV with a total of 30 fractions,normalizing the dose which covers at least 95% of the target volume to 100%.Optimization assessment of physical parameters include V5、V10、V20、V30、V40、V50、V60.,and mean dose for left lung and right lung;and V₅、V₆、V₁₀、V₂₅、V₃₀、V₄₀、V₄₅、V₅₅、V₆₀、D₅、D₁₀、D₂₀、D₃₀、D₄₀、D₅₀、D₆₀、D₇₀、D₈₀、D₉₀、D₁₀₀、Mean,and mean dose for heart.Spinal maximum dose,Dmax,is 45 Gy.Statistical analysis algorithm is SPSS 17.0 statistical software.T-test were conducted among Plan A,Plan B and Plan C.P <0.05 was considered statistically significant.Statistical analysis showed that for lung cancer,esophageal chest tumor plan design,with Plan B and Plan C,the heart and lung tissue index parameter index were significantly reduced as compared to Plan A.Furthermore,the reduction of V5,V10 and other small dose volume for lung are more significant.At the same time the dose volume of other normal tissues may be increased,but were in their clinical tolerance range.For Plan C,the dose volume of heart declines more obviously.In conclusion,by comparing Plan A,Plan B and Plan C,most indicators have reached the desired goals for Plan B and Plan C.Hence,for the chest cancer patients with the individual differences as their first priority,Plan B is recommended for poor pulmonary function patient,and Plan C is recommended for the patient with a poor heart function.