Department of Medical Physics and Biomedical Engineering, University College London, Gower Street, London, United Kingdom.
Neuro-Oncology Team, Department of Oncology, University College London Hospital NHS Foundation Trust, 250 Euston Road, London, United Kingdom.
Br J Radiol. 2023 Jun 1;96(1146):20220384. doi: 10.1259/bjr.20220384. Epub 2023 Apr 27.
Glioblastoma (GBM) is the most common malignant primary brain tumor with local recurrence after radiotherapy (RT), the most common mode of failure. Standard RT practice applies the prescription dose uniformly across tumor volume disregarding radiological tumor heterogeneity. We present a novel strategy using diffusion-weighted (DW-) MRI to calculate the cellular density within the gross tumor volume (GTV) in order to facilitate dose escalation to a biological target volume (BTV) to improve tumor control probability (TCP).
The pre-treatment apparent diffusion coefficient (ADC) maps derived from DW-MRI of ten GBM patients treated with radical chemoradiotherapy were used to calculate the local cellular density based on published data. Then, a TCP model was used to calculate TCP maps from the derived cell density values. The dose was escalated using a simultaneous integrated boost (SIB) to the BTV, defined as the voxels for which the expected pre-boost TCP was in the lowest quartile of the TCP range for each patient. The SIB dose was chosen so that the TCP in the BTV increased to match the average TCP of the whole tumor.
By applying a SIB of between 3.60 Gy and 16.80 Gy isotoxically to the BTV, the cohort's calculated TCP increased by a mean of 8.44% (ranging from 7.19 to 16.84%). The radiation dose to organ at risk is still under their tolerance.
Our findings indicate that TCPs of GBM patients could be increased by escalating radiation doses to intratumoral locations guided by the patient's biology ( cellularity), moreover offering the possibility for personalized RT GBM treatments.
A personalized and voxel level SIB radiotherapy method for GBM is proposed using DW-MRI, which can increase the tumor control probability and maintain organ at risk dose constraints.
胶质母细胞瘤（GBM）是最常见的恶性原发性脑肿瘤，放疗（RT）后会局部复发，这也是最常见的失败模式。标准 RT 实践在不考虑肿瘤影像学异质性的情况下，将处方剂量均匀应用于肿瘤体积。我们提出了一种新策略，使用弥散加权（DW）MRI 来计算大体肿瘤体积（GTV）内的细胞密度，以便将剂量递升到生物靶区（BTV），从而提高肿瘤控制概率（TCP）。
利用十名接受根治性放化疗的 GBM 患者的 DW-MRI 预处理表观弥散系数（ADC）图，根据已发表的数据计算局部细胞密度。然后，使用 TCP 模型从推导的细胞密度值计算 TCP 图。使用同时整合升压（SIB）将剂量递升到 BTV，BTV 定义为预期预升压 TCP 处于每个患者 TCP 范围最低四分位数的体素。SIB 剂量的选择使 BTV 中的 TCP 增加到与整个肿瘤的平均 TCP 相匹配。
通过对 BTV 应用 3.60 Gy 至 16.80 Gy 等剂量 SIB，该队列的计算 TCP 平均增加了 8.44%（范围为 7.19%至 16.84%）。危及器官的辐射剂量仍在其耐受范围内。
我们的研究结果表明，通过在患者生物学（细胞密度）的指导下将辐射剂量递升到肿瘤内部位，可以提高 GBM 患者的 TCP，并且为个性化 RT GBM 治疗提供了可能性。
使用 DW-MRI 提出了一种针对 GBM 的个性化和体素级 SIB 放疗方法，它可以提高肿瘤控制概率并保持危及器官剂量限制。
