Brewster Frank, Middleton Zoe, McWilliam Alan, Brocklehurst Andrew, Radhakrishna Ganesh, Chuter Robert
Christie Medical Physics and Engineering, The Christie NHS Foundation Trust, Manchester, UK.
Leeds Teaching Hospitals NHS Trust, Leeds, UK.
Clin Transl Radiat Oncol. 2024 Sep 13;49:100859. doi: 10.1016/j.ctro.2024.100859. eCollection 2024 Nov.
Tumours in the liver often develop on a background of liver cirrhosis and impaired liver function. As a result, radiotherapy treatments are limited by radiation-induced liver disease, parameterised by the liver mean dose (LMD). Liver function is highly heterogeneous, especially in liver cancer, but the use of LMD does not take this into account. One possible way to improve liver treatments is to use quantitative imaging techniques to assess liver health and prioritise the sparing of healthy liver tissue.
Anatomical T2 and quantitative iron-corrected T1 (cT1) images were made available for 10 patients with liver metastases. Functional liver volumes were automatically segmented on the quantitative images using a threshold. Liver stereotactic ablative body radiotherapy (SABR) plans were made using a departmental protocol. Liver-sparing plans were then made by reducing the dose to the functional sub-volume.
The sparing plans achieved a statistically significant ( ) reduction in the functional liver mean dose, with a mean reduction of 1.4 Gy. The LMD was also significantly different ( ) but had a smaller magnitude with a mean reduction of 0.7 Gy. There were some differences in the planning target volume D ( ) but the sparing plans remained within the optimal tolerance and the D was not significantly different ( ).
This study has, for the first time, demonstrated the use of cT1 maps in radiotherapy showing significant reductions in dose to the healthy liver. Further work is needed to validate this in liver cancer patients, who would likely benefit most.
肝脏肿瘤常发生于肝硬化及肝功能受损的背景下。因此，放射治疗受放射性肝病限制，以肝脏平均剂量（LMD）作为参数。肝功能具有高度异质性，尤其是在肝癌中，但LMD的使用并未考虑到这一点。改善肝脏治疗的一种可能方法是使用定量成像技术来评估肝脏健康状况，并优先保护健康肝脏组织。
为10例肝转移患者提供了解剖T2图像和定量铁校正T1（cT1）图像。使用阈值在定量图像上自动分割功能性肝体积。根据科室方案制定肝脏立体定向消融体部放射治疗（SABR）计划。然后通过降低对功能性子体积的剂量来制定肝脏保护计划。
保护计划使功能性肝脏平均剂量在统计学上有显著（ ）降低，平均降低1.4 Gy。LMD也有显著差异（ ），但降低幅度较小，平均降低0.7 Gy。计划靶体积D（ ）存在一些差异，但保护计划仍在最佳耐受范围内，且D无显著差异（ ）。
本研究首次证明了在放射治疗中使用cT1图谱可显著降低对健康肝脏的剂量。需要进一步开展工作，在可能受益最大的肝癌患者中对此进行验证。
