Lee Larissa J, Sadow Cheryl A, Russell Anthony, Viswanathan Akila N
Harvard Radiation Oncology Program, Department of Radiation Oncology, Brigham and Women's Hospital/Dana-Farber Cancer Institute, 75 Francis Street, Boston, MA 02115, USA.
Int J Radiat Oncol Biol Phys. 2009 Nov 1;75(3):803-9. doi: 10.1016/j.ijrobp.2008.11.052. Epub 2009 Mar 13.
To compare high dose rate (HDR) point B to pelvic lymph node dose using three-dimensional-planned brachytherapy for cervical cancer.
Patients with FIGO Stage IB-IIIB cervical cancer received 70 tandem HDR applications using CT-based treatment planning. The obturator, external, and internal iliac lymph nodes (LN) were contoured. Per fraction (PF) and combined fraction (CF) right (R), left (L), and bilateral (Bil) nodal doses were analyzed. Point B dose was compared with LN dose-volume histogram (DVH) parameters by paired t test and Pearson correlation coefficients.
Mean PF and CF doses to point B were R 1.40 Gy +/- 0.14 (CF: 7 Gy), L 1.43 +/- 0.15 (CF: 7.15 Gy), and Bil 1.41 +/- 0.15 (CF: 7.05 Gy). The correlation coefficients between point B and the D100, D90, D50, D2cc, D1cc, and D0.1cc LN were all less than 0.7. Only the D2cc to the obturator and the D0.1cc to the external iliac nodes were not significantly different from the point B dose. Significant differences between R and L nodal DVHs were seen, likely related to tandem deviation from irregular tumor anatomy.
With HDR brachytherapy for cervical cancer, per fraction nodal dose approximates a dose equivalent to teletherapy. Point B is a poor surrogate for dose to specific nodal groups. Three-dimensional defined nodal contours during brachytherapy provide a more accurate reflection of delivered dose and should be part of comprehensive planning of the total dose to the pelvic nodes, particularly when there is evidence of pathologic involvement.
使用三维计划近距离放射治疗宫颈癌，比较高剂量率（HDR）B点剂量与盆腔淋巴结剂量。
国际妇产科联盟（FIGO）分期为IB-IIIB期的宫颈癌患者接受了70次基于CT治疗计划的串联HDR治疗。对闭孔、髂外和髂内淋巴结（LN）进行轮廓勾画。分析了每次分割（PF）以及累计分割（CF）时右侧（R）、左侧（L）和双侧（Bil）淋巴结的剂量。通过配对t检验和Pearson相关系数比较B点剂量与淋巴结剂量体积直方图（DVH）参数。
B点的平均PF和CF剂量分别为：右侧1.40 Gy±0.14（CF：7 Gy），左侧1.43±0.15（CF：7.15 Gy），双侧1.41±0.15（CF：7.05 Gy）。B点与淋巴结D100、D90、D50、D2cc、D1cc和D0.1cc之间的相关系数均小于0.7。仅闭孔淋巴结的D2cc和髂外淋巴结的D0.1cc与B点剂量无显著差异。观察到右侧和左侧淋巴结DVH之间存在显著差异，这可能与串联装置偏离不规则肿瘤解剖结构有关。
对于宫颈癌的HDR近距离放射治疗，每次分割的淋巴结剂量近似于远距离放射治疗的等效剂量。B点不能很好地替代特定淋巴结组的剂量。近距离放射治疗期间三维定义的淋巴结轮廓能更准确地反映所给予的剂量，应成为盆腔淋巴结总剂量综合计划的一部分，尤其是在有病理受累证据时。
