Abed Jessy, Lee Jenny, Craig Tim, Berlin Alejandro, Ménard Cynthia, Chung Peter
Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Ontario, Canada.
Radiation Medicine Program, Princess Margaret Hospital, University Health Network, Ontario, Canada.
J Med Imaging Radiat Sci. 2017 Dec;48(4):336-342. doi: 10.1016/j.jmir.2017.09.014. Epub 2017 Nov 29.
Local control in prostate cancer may be improved with targeted dose escalation to regions with high tumour burden. Multiparametric magnetic resonance imaging (mpMRI) combined with MRI-guided biopsies may aid in defining tumour-dense regions before radiation therapy. Deformable registration techniques may be used to map these tumour regions onto the radiotherapy planning MRI. Radiation therapy delivery techniques such as volumetric modulated arc therapy and high-dose-rate brachytherapy may allow for highly conformal dose escalation, and when coupled with image-guided radiation delivery (ie, cone beam computed technology and fiducial markers), may allow high-precision dose-escalated treatment.
Eligible prostate cancer patients were enrolled on a prospective trial of tumour dose escalation. Two strategies were investigated: (1) an integrated boost to external beam radiation for a total tumour dose of 95 Gy in 38 fractions or (2) a focal high-dose-rate boost of 10 Gy before 76 Gy in 38 fractions external beam radiation. Patients underwent MRI-guided biopsy with fiducial marker placement before therapy. mpMRI was acquired and used in conjunction with a non-endorectal coil T2 MRI and computed technology simulation images to define the gross tumour volume via a deformable registration approach for intraprostatic tumour dose escalation.
A case example for each dose escalation strategy illustrates the tumour-targeted approach using MRI guidance.
Combining mpMRI sequences with a deformable registration approach may aid in more accurate and reproducible definition of tumour-dense regions. This novel process coupled with daily image guidance may allow high-precision dose-escalated tumour-targeted radiotherapy for prostate cancer.
通过对肿瘤负荷高的区域进行靶向剂量递增，可改善前列腺癌的局部控制。多参数磁共振成像（mpMRI）与MRI引导下的活检相结合，可能有助于在放射治疗前确定肿瘤密集区域。可变形配准技术可用于将这些肿瘤区域映射到放射治疗计划MRI上。容积调强弧形放疗和高剂量率近距离放疗等放射治疗技术可实现高度适形的剂量递增，并且与图像引导放射治疗（即锥形束计算机断层扫描技术和基准标记）相结合时，可实现高精度的剂量递增治疗。
符合条件的前列腺癌患者参加了一项肿瘤剂量递增的前瞻性试验。研究了两种策略：（1）对体外照射进行综合增敏，总肿瘤剂量为95 Gy，分38次照射；或（2）在38次体外照射76 Gy之前进行10 Gy的局部高剂量率增敏。患者在治疗前接受了MRI引导下的活检并放置了基准标记。采集mpMRI，并将其与非直肠内线圈T2 MRI和计算机断层扫描技术模拟图像结合使用，通过可变形配准方法定义前列腺内肿瘤剂量递增的大体肿瘤体积。
每个剂量递增策略的一个病例示例说明了使用MRI引导的肿瘤靶向方法。
将mpMRI序列与可变形配准方法相结合，可能有助于更准确、可重复地定义肿瘤密集区域。这个新过程与每日图像引导相结合，可能允许对前列腺癌进行高精度的剂量递增肿瘤靶向放疗。
