三维适形放疗与调强放疗治疗原发性肝癌伴门静脉癌栓的剂量学比较

目的评估三维适形放疗(3DCRT)与调强放疗(IMRT)2种不同放疗技术在原发性肝癌伴门静脉癌栓放射治疗中的优缺点。方法 20例不能手术的原发性肝癌并门静脉癌栓的患者分别进行3DCRT和IMRT 2种放疗计划设计,处方剂量均为40 Gy/20 f。比较2组计划的靶区与危及器官剂量学参数及加速器跳数(MU)。2组间比较采用t检验。结果 IMRT在计划靶体积(PTV)的剂量覆盖、均一性及适形度均优于3DCRT(P0.05);3DCRT与IMRT的肝V30 Gy及肝V20 Gy分别为33.55±5.67vs 29.41±2.67(P=0.001)和44.24±6.17 vs 41.28±4.59(P=0.021)。2组的正常肝组织低剂量区范围与胃、小肠、脊髓、双肾的受照射剂量并无显著性差异。3DCRT与IMRT的MU分别为303.7±35.8和377.4±33.2(P=0.000)。结论与3DCRT相比,IMRT有较满意的PTV高剂量覆盖及均匀的剂量分布。在危及器官保护方面,IMRT的肝脏高剂量区范围明显低于3DCRT,而不足的是,IMRT的治疗时间显著长于3DCRT。

Dosimetric comparison of 3DCRT and IMRT in treatment of primary hepatocellular carcinoma with portal vein tumor thrombus

Objective To compare three -dimensional conformal radiotherapy （3DCRT） and intensity -modulated radiotherapy （IMRT） in terms of their advantages of disadvantages in the treatment of primary hepatoeellular carcinoma （ PHC ） with portal vein tumor thrombus （ PVT＇F）. Methods Twenty patients with PHC accompanied by PVTF were enrolled in this study. Each patient underwent 3DCRT and IM RT with a prescribed dose of 40 Gy/20 fractions. The parameters included the conformity index （CI） , homogeneity index （HI） , mean dose （Dmean） , minimum dose （Dmin） , maximum dose （Dmax） , V95%, V100% , and V105% for planning target volume （PTV）, the num ber of monitor units （MUs） for evaluating planning efficiency, and Dmean, Dmax, and Dmin for the organs at risk （OAR）. The percentage of the normal liver volume receiving ≥30, 〉20, 〉 10, and 〉5 Gy （V30 Gy, V20 Gy, V10 Gy, and V5 Gy, respectively） were calculat ed to determine liver toxicity. The two radiotherapy regimens were compared in terms of the dosimetric parameters for PTV and OAR, as well as number of MUs. Results IMRT had significantly higher Dmin, Dmean, V95% , and V100% and significantly better HI and CI com pared with 3DCRT （P 〈 0.05）. The liver V30 Gy and V20 Gy were 33.55 ± 5.67 and 44.24± 6.17, respectively, for 3DCRT, versus 29.41 ±2. 67 and 41.28 ±4.59 for IMRT （P =0. 001 ; P =0.021 ）. There were no significant differences in liver V10 Gy, liver V5 Gy, stomach Dmax, small intestine Dmax, spinal cord Dmax, kidney Dmax, and kidney V20 Gy between IMRT and 3DCRT. The number of MUs was 303.7 ±35.8 for 3DCRT and 377.4 ± 33.2 for IMRT （P = 0. 000）. Conclusion IMRT provides higher tumor coverage, homoge neity, and conformity, as well as better normal liver tissue sparing, as compared with 3DCRT. However, IMRT is not superior to 3DCRT in terms of treatment efficiency.