PET/CT图像融合对骨转移瘤放射治疗肿瘤区勾画的影响

Value of integrated positron-emission tomography and computed tomography in gross tumor volume delineation for radiotherapy for bone metastasis

目的评价PET/CT图像融合在三维适形放射治疗骨转移瘤肿瘤靶区勾画中的作用.方法选取3例病理证实原发灶为肺癌、肝癌和肾癌且合并全身多发性骨转移瘤患者,选择腰椎、胸椎、肋骨、髂骨、肩胛骨、股骨转移病灶各1处,标记为BM1～6,由8位放射肿瘤学医师分别在治疗计划CT上勾画6处骨转移瘤的肿瘤区体积(GTV),比较依据CT和PET/CT图像融合资料勾画GTv的差异.结果有骨皮质破坏的病灶BM1～5,依据CT勾画的GTV较依据PET/CT勾画的GTV大(P<0.05),而无明显骨皮质破坏的病灶BM6则相反(P<0.05).依据PET/CT勾画GTV时,不同观察者之间的差异小于依据CT勾画GTV时的差异.结论 PET/CT图像融合能提高骨转移瘤GTV勾画的精确性和重复性,从而减少对周围正常组织损伤而增加放射治疗的增益比.

Objective To evaluate the role of integrated positron-emission tomography and computed tomography (PET/CT) in gross tumor volume (GTV) delineation for three-dimensional conformal radiotherapy for bone metastasis. Methods Three patients with multiple bone metastases were enrolled in this study, whose primary tumors were pathologically identified as lung cancer, liver cancer and renal cell carcinoma. In each case, 6 sites of bone metastases were selected, labeled as BM1 to BM6 which located in the lumbar, thoracic vertebra, rib, ilium, scapula and thighbone respectively. The GTVs of the 6 bone metastases were delineated on the CT scans for treatment planning by 8 radiation oncologists, and the results were compared with the delineation obtained on the basis of integrated CT and PET/CT for analyzing the interobserver variability. Results For BM1-5 with obvious bone cortex lesions by the carcinoma, the GTV delineated on the basis of CT was greater than that derived from PET/CT (P<0.05), whereas for BM6 with intact bone cortex, the contrary result was observed (P<0.05). For any of these bone metastasis, the interobserver variability in GTV delineation with PET/CT was less than that with CT. Conclusion PET/CT is useful for improving the accuracy of GTV delineation for the protection of the normal tissues during radiotherapy.