Pellizzon Antonio Cassio Assis
Departamento de Radio-Oncologia, A.C.Camargo Cancer Center, São Paulo, SP, Brasil.
Rev Assoc Med Bras (1992). 2020 Jun;66(6):728-731. doi: 10.1590/1806-9282.66.6.728. Epub 2020 Jul 20.
Voluminous tumors represent a challenge in radiation oncology, particularly when surgical resection is not possible. Lattice radiotherapy (LTR) is a technique that may provide equivalent or superior clinical response in the management of large tumors while limiting toxicity to adjacent normal tissues. LRT can precisely deliver inhomogeneous high doses of radiation to different areas within the gross tumor volumes (GTV). The dosimetric characteristic of LTR is defined by the ratio of the valley dose (lower doses - cold spots) and the peak doses, also called vertex (higher doses - hot spots), or the valley-to-peak dose ratio. The valley-to-peak ratio thereby quantifies the degree of spatial fractionation. LRT delivers high doses of radiation without exceeding the tolerance of adjacent critical structures. Radiobiological experiments support the role of radiation-induced bystander effects, vascular alterations, and immunologic interactions in areas subject to low dose radiation. The technological advancements continue to expand in Radiation Oncology, bringing new safety opportunities of treatment for bulky lesions.
巨大肿瘤对放射肿瘤学来说是一项挑战，尤其是在无法进行手术切除时。点阵放射治疗（LTR）是一种技术，在大型肿瘤的治疗中可能提供等效或更好的临床反应，同时限制对相邻正常组织的毒性。LRT可以精确地向大体肿瘤体积（GTV）内的不同区域输送不均匀的高剂量辐射。LTR的剂量学特征由谷剂量（较低剂量——冷点）与峰值剂量（也称为顶点，较高剂量——热点）的比值定义，即谷峰剂量比。谷峰比从而量化了空间分割的程度。LRT输送高剂量辐射而不超过相邻关键结构的耐受度。放射生物学实验支持低剂量辐射区域中辐射诱导的旁观者效应、血管改变和免疫相互作用所起的作用。放射肿瘤学的技术进步不断扩展，为体积较大的病变带来了新的安全治疗机会。
