Zhang Hualin, Wang Jian Z, Mayr Nina, Kong Xiang, Yuan Jiankui, Gupta Nilendu, Lo Simon, Grecula John, Montebello Joseph, Martin Douglas, Yuh William
Department of Radiation Medicine, The Ohio State University, 300 West 10th Avenue, Columbus, OH 43210-1228, USA.
Int J Radiat Oncol Biol Phys. 2008 Jan 1;70(1):280-8. doi: 10.1016/j.ijrobp.2007.08.024. Epub 2007 Oct 29.
To evaluate the conventionally fractionated and hypofractionated grid therapy in debulking cervical cancers using the linear quadratic (LQ) model.
A Monte Carlo technique was used to calculate the dose distribution of a commercially available grid in a 6-MV photon beam. The LQ model was used to evaluate the therapeutic outcome of both the conventionally fractionated (2 Gy/fraction) and hypofractionated (15 Gy/fraction) grid therapy regimens to debulk cervical cancers with different LQ parameters. The equivalent open-field dose (EOD) to the cancer cells and therapeutic ratio (TR) were defined by comparing grid therapy with the open debulking field. The clinical outcomes from 114 patients were used to verify our theoretical model.
The cervical cancer and normal tissue cell survival statistics for grid therapy in two regimens were calculated. The EODs and TRs were derived. The EOD was only a fraction of the prescribed dose. The TR was dependent on the prescribed dose and the LQ parameters of both the tumor and normal tissue cells. The grid therapy favors the acutely responding tumors inside radiosensitive normal tissues. Theoretical model predictions were consistent with the clinical outcomes.
Grid therapy provided a pronounced therapeutic advantage in both the hypofractionated and conventionally fractionated regimens compared with that seen with single fraction, open debulking field regimens, but the true therapeutic advantage exists only in the hypofractionated grid therapy. The clinical outcomes and our study indicated that a course of open-field radiotherapy is necessary to control tumor growth fully after a grid therapy.
使用线性二次（LQ）模型评估常规分割和大分割格栅治疗在宫颈癌减瘤中的效果。
采用蒙特卡罗技术计算6兆伏光子束中商用格栅的剂量分布。LQ模型用于评估常规分割（2 Gy/分次）和大分割（15 Gy/分次）格栅治疗方案对不同LQ参数的宫颈癌减瘤的治疗效果。通过将格栅治疗与开放减瘤野进行比较，定义癌细胞的等效开放野剂量（EOD）和治疗比（TR）。使用114例患者的临床结果来验证我们的理论模型。
计算了两种方案中格栅治疗的宫颈癌和正常组织细胞存活统计数据。得出了EOD和TR。EOD仅是处方剂量的一小部分。TR取决于处方剂量以及肿瘤和正常组织细胞的LQ参数。格栅治疗有利于放射敏感正常组织内急性反应性肿瘤。理论模型预测与临床结果一致。
与单次分割、开放减瘤野方案相比，格栅治疗在大分割和常规分割方案中均具有显著的治疗优势，但真正的治疗优势仅存在于大分割格栅治疗中。临床结果和我们的研究表明，在格栅治疗后，有必要进行一个疗程的开放野放疗以充分控制肿瘤生长。
