Experimental Study on Stereotactic Radiotherapy and Ir-192 High Dose Rate Brachytherapy of Liver Cancer

为了评价立体定向放疗和Ir-192高剂量率（HDR）近距离放疗对肝癌的治疗效果，采用兔正常肝和VX2移植瘤进行了实验研究。在距Ir-192源5mm处给予正常兔肝脏40Gy剂量。间质性近距离放射治疗5天后肝脏组织学表现为肝细胞坏死或凋亡及异物肉芽肿伴出血。离源较远的肝细胞基本正常。应用立体定向放射外科系统对后肢VX2肿瘤进行放射治疗。整个肿瘤组织给予40 Gy的剂量。立体定向放疗5天后肿瘤组织学表现为几乎所有肿瘤细胞坏死和凋亡。VX2肿瘤也行Ir-192 HDR间质近距离放疗。VX2肿瘤在距源5mm处给予40Gy剂量。近距离放疗后5天肿瘤组织学表现为肿瘤源附近细胞坏死或凋亡。肝细胞和VX2肿瘤细胞的凋亡和坏死被认为是辐射效应。立体定向放疗对VX2肿瘤的治疗效果优于Ir-192 HDR近距离放疗，因为剂量分布不同。定向放疗可能是一种很有前途的肝癌治疗手段。立体定向放射治疗一次给药高剂量，无侵袭性。

To evaluate effect of stereotactic radiotherapy and Ir-192 high dose rate(HDR) brachytherapy on liver cancer, experimental study was performedusing normal liver and transplanted VX2 tumor in the rabbits. A dose of 40Gy at a distance 5mm from Ir-192 source was given to normal liver of rabbits. Histological findings of the liver 5 days after interstitial brachytherapy showed necrosis or apoptosis of hepatic cells and foreign body granuloma with hemorrhage. Hepatic cells at long distance from the source were essentially normal. VX2 tumors transplanted in the muscle of hind leg were irradiated by stereotactic radiosurgery system. A dose of 40 Gy was administrated to the whole tumor tissue. Histological findings of the tumor 5 days after stereotactic radiotherapy showed necrosis and apoptosis of almost all tumor cells. VX2 tumors were also irradiated by Ir-192 HDR interstitial brachytherapy. A dose of 40Gy at a distance 5mm from the source was given to VX2 tumors. Histological findings of the tumor 5days after brachytherapy showed necrosis or apoptosis of tumor cells near the source. Apoptosis and necrosis of hepatic cells and VX2 tumor cells were thought to be radiation effects. Therapeutic effect of stereotactic radiotheapy on VX2 tumors was superior to that of Ir-192 HDR brachytherapy, because of the difference of dose distributions.Streotactic radiotherapy may be a promising therapeutic tool for liver cancer. High dose administration to tumor at one time can be achieved by stereotactic radiotherapy without invasiveness.