模拟调强放疗照射离体细胞的质量保证

目的：在模拟调强放疗方式照射细胞的过程中，保证细胞按调强方式被照射，照射剂量准确。方法：在细胞培养瓶中装满细胞培养液，水平固定在标准水箱（30cm×30cm×30cm）电离室横梁上，在水箱中加水到电离室上方5cm，用CT机（philips brilliance bigbor CT）扫描获取图像，传到计划系统（ECLIPSE 7．0）中；再用一个空的培养瓶替换装满培养液的培养瓶，重新用CT机扫描，获取图像，传到计划系统中。采用先设野中野后合并野中野的设计方法，设计模拟调强照射计划，设定电离室处的吸收剂量400cGy。再把此水箱放到加速器（Varian 600-C／D）下，按设计的模拟调强照射计划进行照射，同时用电离室（NE 0．6cc）剂量仪（NE FARMER 2570）测量得到实际吸收剂量。结果：在细胞培养瓶中装满细胞培养液时模拟调强照射实测得到397cGy，与理论值相差-0．8％；在细胞培养瓶中不装细胞培养液时模拟调强照射实测得到395cGy，与理论值相差-1.3％。结论：用CT模拟定位，用计划系统通过设野中野的方法设计模拟调强照射计划是可行的，可以实现模拟调强照射离体细胞，理论剂量与实测剂量相差小于2％。

Quality Assurance of Irradiating Vitro Cell in Intensity Modulated Radiation Therapy Model

Objective： To assure the absorbed dose of the vitro cell irradiated is exact and the irradiation is in intensity modulated radition therapy model. Methods： Fill the cell culture solution to full in the culture flask and Fix its level on ionization room crossbeam in standard water box（30 cm×30 cm×30 cm）, its water is added to superjacent 5 centimetres place of ionization room. Use CT machine（PHILIPS Brilliance Bigbor CT） to scan a water box, to gain images, sending these images to the treatment plan system （ECLIPSE 7.0）. Substitute a empty space culture flask for the culture flask filling a culture solution to full again, in again, using CT machine to scan, gain images, sending these images to the treatment plan system. Design IMRT （intensity modulated radiation therapy） plan by merging fields in field. The absorbed dose setting up the ionization room place are 400 cGy. Irradiating the water box in the accelerator （Varian 600-C/D） according the IMRT plan, measure the reality absorbed dose in this water box by using the ionization room dosemeter （NE FARMER 2570, NE 0.6 cc）. Results： Reality measures the irradiation simulating IMRT when filling the cell culture solution to full in cell culture flask getting 397 cGy, and theory value differ by 0.8%; reality measures the irradiation simulating IMRT when not holding the cell culture solution with in cell culture flask getting 395 cGy, and theory value differ by 1.3%. Conclusion： It is feasible that localization using a CT simulator and designing IMRT plan to irradiate vitro cell. Theory dose differ by from to measuring dose really being smaller than 2%.