关键词: 胃肿瘤;放射疗法,适形;放射治疗剂量;对比研究

Abstract:

Objective   To evaluate threedimension  conformal radiation therapy (3D-CRT)， intensity-modulated radiation therapy (IMRT) and simplified intensity-modulated   radiation therapy (sIMRT) in post-operative radiotherapy for gastric cancer. Methods   A total of 10 patients with gastric body cancer were chosen for this study. All were of the T3 or T4 type, with or without  lymph  node metastasis, and surgery had been performed. All patients were  subjected to 3D-CRT, IMRT and sIMRT   treatment regimes. The dose prescriptions were 45.00Gy to 95％ of PTV and 42.75Gy to 99％ of PTV． DVHs and 3D dose distributions of the three regimes were compared． Results   IMRT， sIMRT and 3D-CRT had  comparable PTV coverages with the prescribed doses, but IMRT and sIMRT  showed better dose conformity than 3D-CRT． For a normal liver， V23, V30 and mean dose  for IMRT and sIMRT  were similar and  lower than those for 3D-CRT, although these doses were  still within the clinical tolerance range for 3D-CRT． V15 and  V23 for sIMRT showed the lowest doses for kidneys, as contrasted to  3D-CRT being the highest． IMRT, sIMRT and 3D-CRT  had comparable maximum doses to the spinal cord． Conclusions   IMRT， sIMRT and 3D-CRT have adequate and  accurate PTV coverages for the prescribed doses in postoperative radiotherapy for gastric carcinoma，and can protect  neighboring organs.  Overall, sIMRT is the best among the three  techniques.

Key words:  Stomach carcinomas; Radiotherapy, conformal; Dosage ； Control study