The Institute of Cancer Research and Royal Marsden NHS Trust, Head and Neck Radiotherapy and Imaging, Sutton, United Kingdom.
Joint Department of Physics, The Institute of Cancer Research and Royal Marsden NHS Trust, Sutton, United Kingdom.
Br J Radiol. 2020 Jul;93(1111):20200023. doi: 10.1259/bjr.20200023. Epub 2020 May 21.
This study investigates the impact of a restricted craniocaudal (CC) field length of <20 cm on the selection of head and neck cancer (HNC) patients who can be treated on the MR-Linac using a single isocentre technique. We also assess the effects of anthropometric factors and the neck position on the CC field length.
110 HNC patients who underwent radical primary or adjuvant radiotherapy were retrospectively analysed. We assessed the proportion of treatment fields with a CC length of <20 cm and the effects of gender, height, hyo-sternal neck length (distance from superior surface of hyoid to sternal notch measured on the coronal reconstruction of the planning CT) and neck position on CC length.
95% of HNC patients had a CC field length <20 cm. Female patients showed a significantly shorter median CC length than male patients in both extended ( = 0.0003) and neutral ( = 0.008) neck positions. Neck position influenced the median CC length with neutral neck being significantly shorter than extended neck ( = 0.0119). Patient height and hyo-sternal neck length showed positive correlation with the CC length, with neck length in neutral position having the strongest correlation ( = 0.65, = 0.0001 and = 0.63, < 0.0001, respectively for extended neck; = 0.55, = 0.0070 and = 0.80, < 0.0001, respectively for neutral neck). A hyo-sternal neck length of <14.6 cm predicted a CC length of <20 cm in neutral neck position.
The majority of patients with HNC at the Royal Marsden Hospital have anthropometric features compatible with their being treated on the MR-Linac using a single isocentre technique. The absolute CC field size may vary according to primary tumour site, patient factors and neck position. A hyo-sternal neck length cut-off of 14.6 cm in the neutral neck position can be used as a surrogate marker for suitability of treatment on MR-Linac.
This paper highlights the potential impact of a restricted CC field in HNC patient selection for the MR-Linac treatment. This is the first report to suggest the use of neck length as a surrogate marker for suitability of treatment on the MR-Linac.
本研究旨在探讨颅尾（CC）野长度限制在<20cm 对采用单等中心技术在 MR-Linac 上治疗头颈部癌症（HNC）患者的影响。我们还评估了人体测量因素和颈部位置对 CC 野长度的影响。
回顾性分析了 110 例接受根治性原发或辅助放疗的 HNC 患者。我们评估了 CC 长度<20cm 的治疗野比例，以及性别、身高、甲状软骨-胸骨颈长度（在计划 CT 的冠状重建上测量从甲状软骨上表面到胸骨切迹的距离）和颈部位置对 CC 长度的影响。
95%的 HNC 患者 CC 野长度<20cm。在伸展（ = 0.0003）和中立（ = 0.008）颈部位置，女性患者的 CC 长度中位数均明显短于男性患者。颈部位置影响 CC 长度，中立位明显短于伸展位（ = 0.0119）。患者身高和甲状软骨-胸骨颈长度与 CC 长度呈正相关，中立位颈长相关性最强（伸展位分别为 = 0.65， = 0.0001 和 = 0.63， < 0.0001；中立位分别为 = 0.55， = 0.0070 和 = 0.80， < 0.0001）。甲状软骨-胸骨颈长度<14.6cm 可预测中立位 CC 长度<20cm。
皇家马斯登医院的大多数 HNC 患者具有人体测量特征，适合采用单等中心技术在 MR-Linac 上进行治疗。绝对 CC 野大小可能因原发肿瘤部位、患者因素和颈部位置而异。中立位颈长<14.6cm 可作为适合在 MR-Linac 上治疗的替代标志物。
本文强调了 CC 场受限对 HNC 患者选择 MR-Linac 治疗的潜在影响。这是第一篇报告建议使用颈部长度作为适合在 MR-Linac 上治疗的替代标志物。
