Department of Oncology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark.
Department of Oncology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus C, Denmark.
Phys Med. 2019 Mar;59:127-132. doi: 10.1016/j.ejmp.2019.01.017. Epub 2019 Feb 13.
To provide an analysis of dose distribution in sub-structures that could be responsible for urinary toxicity after Image-Guided Adaptive BrachyTherapy (IGABT) in Locally Advanced Cervical Cancer (LACC).
105 LACC patients treated with radiochemotherapy and IGABT were selected. Sub-structures (bladder wall, trigone, bladder neck, urethra) were contoured on IGABT-planning MRIs. D and D, ICRU Bladder-Point (ICRU BP) and Posterior-Inferior Border of Symphysis points (PIBS, PIBS + 2 cm, PIBS - 2 cm) doses were extracted. Internal-Urethral-Ostium (IUO) and PIBS-Urethra (PIBS-U) points were defined as urethral dose surrogates. Finally, the Vaginal Reference Length (VRL) was extracted. Values were converted into total EBRT + BT equivalent dose in 2 Gy fractions using α/β = 3 and T = 1.5 h.
Median D for bladder and trigone were 71.7[interquartile-range:66.5;74.1]Gy and 57.8[53.3;63.6]Gy, respectively, while median D were 82.2[77.6;89.1]Gy and 70.7[62.0;76.7]Gy, respectively. Median ICRU BP dose was 63.7[56.5;70.5]Gy and correlated with trigone D and D, while bladder and trigone D had poor correlation (R = 0.492), as well as D (R = 0.356). Bladder neck D was always lower than trigone D and higher than IUO. Correlation between PIBS + 2 cm and IUO was poor (R = 0.273), while PIBS and PIBS-U were almost equal (R = 0.990). VRL correlated with dose to bladder base.
The study confirmed that ICRU BP and trigone doses correlate. Bladder D is not representative of trigone dose because hotspots are often placed in the bladder dome. VRL is a good indicator for bladder base sparing. In addition to D and D for whole bladder, ICRU BP, trigone D and D, IUO and PIBS are useful for lower urinary tract reporting.
分析在局部晚期宫颈癌（LACC）患者接受图像引导自适应近距离放射治疗（IGABT）后，可能导致尿毒性的亚结构剂量分布。
选择 105 例接受放化疗和 IGABT 治疗的 LACC 患者。在 IGABT 计划 MRI 上勾画亚结构（膀胱壁、三角区、膀胱颈部、尿道）。提取 D 和 D、ICRU 膀胱点（ICRU BP）和坐骨后下边界点（PIBS、PIBS+2cm、PIBS-2cm）剂量。定义尿道内口（IUO）和 PIBS 尿道（PIBS-U）点为尿道剂量替代物。最后，提取阴道参考长度（VRL）。使用 α/β=3 和 T=1.5h 将值转换为总 EBRT+BT 等效剂量，每 2Gy 分数。
膀胱和三角区的中位 D 值分别为 71.7[四分位距：66.5；74.1]Gy 和 57.8[53.3；63.6]Gy，而中位 D 值分别为 82.2[77.6；89.1]Gy 和 70.7[62.0；76.7]Gy。中位 ICRU BP 剂量为 63.7[56.5；70.5]Gy，与三角区 D 和 D 相关，而膀胱和三角区 D 相关性较差（R=0.492），D 也较差（R=0.356）。膀胱颈部 D 始终低于三角区 D，高于 IUO。PIBS+2cm 与 IUO 的相关性较差（R=0.273），而 PIBS 和 PIBS-U 几乎相等（R=0.990）。VRL 与膀胱基底剂量相关。
本研究证实，ICRU BP 和三角区剂量相关。膀胱 D 不能代表三角区剂量，因为热点通常位于膀胱穹窿。VRL 是膀胱基底保护的良好指标。除了整个膀胱的 D 和 D，ICRU BP、三角区 D 和 D、IUO 和 PIBS 对于下尿路报告也很有用。
