子宮頸癌術後照射における骨盤リンパ節領域に対する放射線治療計画支援プログラムの自動描出機能の使用経験

Early experience of the automatic delineation solution equipped with the radiotherapy planning support program for the pelvic lymph node region in postoperative irradiation of cervical cancer

子宮頸癌術後の再発リスク因子として，骨盤リンパ節転移や子宮傍組織浸潤，頸部間質浸潤，腫瘍径や脈管侵襲などが挙げられる。これらの因子の中で，骨盤リンパ節転移陽性例や子宮傍組織浸潤陽性例は再発高リスク群とされ，同時化学放射線療法が標準治療として推奨される^1）。従来，術後照射として全骨盤照射が施行されてきたが，近年では有害事象を減らす目的で強度変調放射線治療（intensity modulated radiation therapy：IMRT）が適用されることが多くなってきた^2）。しかし，照射範囲において骨盤リンパ節領域の臨床的標的体積（clinical target volume：CTV）やリスク臓器の輪郭作成には多くの時間を必要とする。

Postoperative irradiation is the standard therapy for patients with cervical cancer who have undergone surgery and have positive pelvic lymph nodes or are at a high risk of recurrence. But creating a clinical target volume（CTV）in the pelvic lymph node region is a time-consuming task. We have introduced the treatment planning support software system syngo.via RT Image Suite（Siemens Healthineers, Germany）and have used the automatic delineation as a tool to assist treatment planning in clinical practice. However, there have been few reports evaluating the accuracy of the automatic delineation specifically for the pelvic lymph node region. In this study, we report on the accuracy of the automatic delineation, which was assessed by calculating the Dice coefficient using the automatically or manually delineated contour information for the CTV of the pelvic lymph node area and the organs at risk.