The IMRT Dose Conformal Index Evaluation Method And The Clinical Value By Rotaing The Equivalent Plans In The Lung Cancer RT

Background and Purpose The 3-Dimensional Conformal Radiotherapy(3D-CRT)and the Intensity Modulated Radiation Therapy(IMRT)can both make the prescribed-dose distributons more conformed to the 3D shape of the target in 3 dimentions,that bring it possible to give much higher dose to target and to minimize the dose to organs at risk.In this paper,a set of dose conformality index has been proposed to further improve the plan quality.Method:1.A total of 30 patients' plans,of lung cancer,were enrolled in and analyzed with the new proposed conformality index.For those plans which less conformed to the new CIs,were replanned and evaluate the differences of the CIs,dosimetry parameters between the clinical group and the two new replanned groups with paird t-test..2.cancer case was chosed and made plans for a 3 sets of 3 angled coplannar beams,and for a set of 9 angled coplannar beams with each of the beam orintation the same as the 3 sets of 3 angled coplannar beams,in condition that all the four intensiy modulation plans must forced the dose distributions in target much siminar namely the siminar TCP which called in our difinition the equivalent plans The plans were dilivered in following ways:each set of 3 beam's plan and 9 beam's plans were dilivered 30 fractions with a dose 60Gy,and each set of 3 beam's plan was dilivered by rotation with each 20 Gy by 10 fractions.TCPs&NTCPs were caculated out for omparisonsResults:1.The new replaned plans evaluated by using the proposed CIs have shown a big advantage to get a much more dose comformality to the target,and much less hogher dose volumes to OARs,which draw us a conclusion that the new proposed CIs can be used for quantificationally assessing the plan's quality.2.The results have shown that NTCP by rotating 3 set 3 beam'plans is much lower than that by 9 or 3 beam's plans when the TCPs for all plans were kept the same.