Dosimetric Study On 3D-conformal Radiotherapy And Intensity Modulated Radiotherapy For The Postoperative Breast Cancer Patients

chapter I Dosimetric comparision between 3D-conformal radiotherapy and intensity modulated radiotherapy for the breast cancer patients receiving breast-concerving surgeryObjective To evalutate the potential dosimetric benefits and optimal indications of 3D-conformal radiotherapy (3D-CRT) and filed-in-filed intensity modulated radiotherapy (FIF-IMRT),direct aperture optimization intensity modulated radiotherapy (DAO-IMRT) for the intact breast.Materials and methods Ten pantients who received breast-concerving surgery were selected for this study (left 6 case and right 4 case ). For each of patients, three plans were designed in Adac pinnacle system. The total pescribed dose was 50Gy/25fractions, 2Gy /fraction.A dosimetric study on 3D-conformal radiotherapy (3D-CRT) and filed-in-filed intensity modulated radiotherapy (FIF-IMRT),direct aperture optimization intensity modulated radiotherapy (DAO-IMRT) was performed on each patients.We compared the does distribution, dose volume histograms(DVH), dose uniformity in the planning target volume (PTV) and dose received by organs at risk(OARS).Results Both FIF-IMRT and DAO-IMRT can improve dose homogeneity and decrease the volume which received overdoseage. There is no region which received more than 110% prescribed dose. DAO-IMRT can decrease the volume of ipsilateral lung which received overdosage significantly.The hot spots of the heart were also decreased .When compare to 3D-CRT ,V20 and V47.5 of ipsilateral lung were decreasd significantly in DAO-IMRT (The values of P is 0.007 and 0.005,respectively). V47.5 of ipsilateral lung of DAO-IMRT was decreased a little when compared to FIF-IMRT. There were no diffrence in V5 of contralateral breast and total lung among three groups.Conclusion Compared to 3D-CRT, both FIF-IMRT and DAO-IMRT can improve dose homogeneity and remove the hot spots.The best dose uniformity throughout the whole breast in DAO-IMRT plan was achieved. DAO-IMRT can decrease the volume of ipsilateral lung which received overdosage significantly.chapter II Dosimetric comparision between 3D-conformal radiotherapy and filed-in-filed intensity modulated radiotherapy for the breast cancer patients receiving mastectomyObjective To evalutate the potential dosimetric benefits and optimal indications of 3D-conformal radiotherapy (3D-CRT) and filed-in-filed intensity modulated radiotherapy (FIF-IMRT) for the chest wall.Materials and methods Ten pantients who received mastectomy were selected for this study (left 5case and right 5 case ). For each of patients, two plans were designed in Adac pinnacle system. The total pescribed dose was 50Gy/25fractions,2Gy/fraction.A dosimetric comparision of 3D- conformal radiotherapy (3D-CRT) and filed- in-filed intensity modulated radiotherapy (FIF-IMRT) was performed on each patients.We compared the does distribution, dose volume histograms (DVH), dose uniformity in the planning target volume (PTV) and dose received by organs at risk(OARS).Results A better dose uniformity throughout the chest wall in FIF-IMRT plan was achieved.In FIF-IMRT plan ,the Dmax was decreasd,the percentage of PTV receiving more than 103% prescribed dose(V103) decreased from 35.27 % to 18.43%(P<0.001),V105 from 20.09% to 3.89 %(P<0.001), V107 from 8.88% to 0.188% (P=0.002),and there is no region which received more than 110% prescribed dose.The hot spots between two beam were eliminated . V20 of ipsilateral lung was decreasd(P=0.003),The Dmean of contralateral lung, the Dmax and Dmean,V30,V5 of heart ;the Dmean of liver were similar in two plans.The Dmean of contralateral breast(P=0.002) and contralateral lung(P<0.001) were increased,but V5 of contralateral breast(P=0.055) and contralateral lung( P=0.605)decreased a little.Conclusion Compared to 3D-CRT,FIF-IMRT improved the dose uniformity throughout the chest wall,decreased the Dmax of PTV and the volume of hot spots within the breast.The volume of the lung which received high dose was decreased.