Department of Radiation Oncology, Institut Gustave Roussy, Villejuif, France.
Radiother Oncol. 2011 Apr;99(1):73-8. doi: 10.1016/j.radonc.2011.02.002. Epub 2011 Mar 23.
To compare the dose distribution between three-dimensional conformal radiotherapy (3DCRT), intensity modulated radiotherapy (IMRT) with six coplanar beams (6b-IMRT) and IMRT with nine coplanar beams (9b-IMRT) during adjuvant radiotherapy for retroperitoneal sarcoma.
The 10 most recent patients who had received adjuvant radiotherapy were reviewed. Three different treatment plans were generated (3DCRT, 6b-IMRT and 9b-IMRT) to deliver 50.4 Gy in 28 fractions. The dose delivered to the organs at risk (intestinal cavity (IC), contra- and ipsilateral kidney, liver, stomach and whole body), and the conformity index (CI) were compared.
The integral dose to the intestinal cavity was similar with the three modalities but the dose distribution was different, with a change-over around 25 Gy: the V50 and the V40 were reduced five- and twofold, respectively, with IMRT compared to 3DCRT, and the V20 was increased by about 25% with IMRT. A similar integral dose was delivered to the whole body with the three modalities. The treated volume (V95 body) was approximately halved with IMRT compared to 3DCRT, and the CI was twice as good with IMRT than with 3DCRT. As expected, the V5 (body) was higher with IMRT compared to 3DCRT (p<0.0001) (a 12% increase with 6b-IMRT and a 21% increase with 9b-IMRT). Compared to 3DCRT, the mean dose delivered to the contralateral kidney increased from 1.5 to 4-4.4 Gy with IMRT. The number of monitor units was increased with IMRT, especially when nine beams were used instead of six.
As expected, IMRT greatly reduced the high-dose irradiated volume and increased the low-dose exposure of the intestinal cavity, with a change-over around 25 Gy, compared to 3DCRT. The conformity index was compellingly better with IMRT. The integral dose delivered to the whole body was conserved with both 3DCRT and IMRT. Longer follow-up is needed to assess late toxicities to the small bowel, contralateral kidney and the risk of second cancers.
比较腹膜后肉瘤辅助放疗中三维适形放疗（3DCRT）、六野调强放疗（6b-IMRT）和九野调强放疗（9b-IMRT）的剂量分布。
回顾了最近接受辅助放疗的 10 例患者。生成了三种不同的治疗计划（3DCRT、6b-IMRT 和 9b-IMRT），以 28 个分次给予 50.4 Gy。比较了危及器官（肠腔（IC）、对侧和同侧肾脏、肝脏、胃和全身）的剂量和适形指数（CI）。
三种方式的肠腔积分剂量相似，但剂量分布不同，在 25 Gy 左右发生变化：与 3DCRT 相比，IMRT 使 V50 和 V40 分别减少了五倍和两倍，而 V20 则增加了约 25%。三种方式的全身积分剂量相似。与 3DCRT 相比，IMRT 使受照体积（V95 全身）减少了近一半，CI 提高了两倍。与 3DCRT 相比，IMRT 使 V5（全身）更高（p<0.0001）（6b-IMRT 增加 12%，9b-IMRT 增加 21%）。与 3DCRT 相比，对侧肾脏的平均剂量从 1.5 Gy 增加到 4-4.4 Gy。与 3DCRT 相比，IMRT 的剂量明显增加，特别是使用 9 个射野而不是 6 个射野时。
与 3DCRT 相比，IMRT 大大降低了高剂量照射体积，增加了肠腔的低剂量暴露，在 25 Gy 左右发生变化，CI 明显更好。两种方式的全身积分剂量相似。需要更长的随访时间来评估小肠、对侧肾脏的晚期毒性和第二癌症的风险。
