ABSTRACT
Objective To compare the dose distribution of mantle-field radiotherapy using conven-tional radiotherapy(CRT) and four intensity-modulated radiotherapy(IMRT) techniques in stage Ⅰ and Ⅱ Hodgkin's lymphoma(HL). Methods Ten patients with patholocally proved early stage HL underwent CT simulation. Then both CRT and IMRT planning performed using ECLIPS treatment planning system(TPS). The dosimetric parameters of different irradiation plans were analyzed, including conformal index (CI), homo-geneity index (HI), D95 and V95 of planning target volume (PTV), Dmax,Dmean,Dmin,V5,V10,V20 and V30 of the lung, as well as Dmax of the spinal cord. Results The isodose distribution and homogeneity of PTV were better in IMRT plans when compared with CRT plans. Target coverage, target dose conformity and homogene-ity were similar among all the four IMRT techniques. The V30 of the lung using IMRT was lower than using CRT,but the low-dose volume of the lung was higher. Among the four IMRT technique plans,the lung V20 and V30 were lower in plans with more-field technique,but the V5 and V10 were higher. The Dmax of the spinal cord using IMRT was all lower than that using CRT. Conclusions IMRT is better than CRT in target cov-erage, conformity, homogeneity and normal tissue sparing, especially in protecting the spinal cord and decrea-sing high-dose lung volume,though the low-dose lung volume is higher. Seven-field IMRT technique for man-de-field radiotherapy is recommanded.
ABSTRACT
Objective To evaluate the tumor dose distribution of routine radiotherapy plan in esophageal cancer with 3D treatment planning system. Methods For the 19 esophageal cancer patients who were diagnosed, the thoracic CT were done and GTV, CTV and PTV were delineated on the image of CT. Then a routine 3 field radiotherapy planning was produced using the Cad Plan 6.4.7 treatment planning system. The dosimetric results of GTV, CTV and PTV, target conformity and the dosimetric uniformity of variant target volume gained from DVH were compared. Results The maximal dose of GTV, CTV and PTV was 51.64Gy, 51.94Gy, 51.48Gy, respectively; the minimal dose was 41.17 Gy, 25.31 Gy, 18.94 Gy, respectively; the mean dose was 49.5 Gy, 47.34 Gy, 42.92 Gy, respectively; the conformity index was 0.94, 0.69, 0.38, respectively; and the dose variability was 2.2 Gy, 7.57 Gy, 14.56 Gy. Conclusions The routine radiotherapy plan in esophageal cancer could not offer satisfactory dose distribution. The method of CT simulation and 3D treatment planning systems should be applied to decide treatment planning.