Fukumitsu Nobuyoshi, Mima Masayuki, Demizu Yusuke, Suzuki Takeshi, Ishida Takaki, Matsushita Kei, Yamaguchi Raizo, Fujisawa Masato, Soejima Toshinori
Department of Radiation Oncology, Kobe Proton Center, Kobe, Japan.
Department of Radiation Oncology, Kobe Proton Center, Kobe, Japan.
Pract Radiat Oncol. 2022 May-Jun;12(3):226-235. doi: 10.1016/j.prro.2021.10.010. Epub 2021 Nov 18.
The purpose of this study is to improve the placement of a hydrogel spacer in patients with prostate cancer receiving radiation therapy.
A total of 160 patients with prostate cancer were classified into 3 groups: No spacer (group 1; n = 30), spacer placed using conventional technique (group 2; n = 100), and spacer placed using new technique (group 3; n = 30). When placing the spacer, the tip of the needle is placed at the middle of the prostate gland (group 2), or at a level corresponding to a cranial:caudal ratio of 6:4 and as close to the prostate gland as possible (group 3). The separation effect was examined and compared among the groups.
The separation in group 2 was larger than that in group 1 from the base to the apex level of the prostate (4 mm), but the separation in group 3 was larger than that in group 2 from the middle to the apex level of the prostate (4 mm). The separation values for the middle to the apex, the spacer thickness from the apex level to the apex (10 mm), the rectal exclusion from the middle to the apex, and the laterality were correlated with the 50 and 60 Gy relative biologic effectiveness (Gy[RBE]) rectal dose (P = 4.1 × 10 - .046). The separation vales were strongly correlated with the spacer thickness at the apex (10 mm) and the apex (4 mm; P = 1.1 × 10 - 1.8 × 10). The rectal volumes at 10 to 60 Gy(RBE) differed among the groups (P = 5.1 × 10 - 5.4 × 10). The rectal volumes in group 2 were smaller than those in group 1 at all dose levels, but those in group 3 were smaller than those in group 2 at dose levels of 30 to 50 Gy(RBE).
The separation, spacer thickness, and rectal exclusion from the middle to the apex of the prostate and the laterality of the hydrogel spacer affected the reduction in the rectal dose. The rectal dose can be further reduced by implanting a spacer on the caudal and prostate side.
本研究旨在改善接受放射治疗的前列腺癌患者水凝胶间隔物的放置。
总共160例前列腺癌患者被分为3组：无间隔物组（第1组；n = 30）、采用传统技术放置间隔物组（第2组；n = 100）和采用新技术放置间隔物组（第3组；n = 30）。放置间隔物时，将针尖端置于前列腺中部（第2组），或置于头端与尾端比例为6:4且尽可能靠近前列腺的水平位置（第3组）。对各组之间的分离效果进行检查和比较。
从前列腺底部到尖部水平，第2组的分离度比第1组大（4毫米），但从前列腺中部到尖部水平，第3组的分离度比第2组大（4毫米）。从中间到尖部的分离值、从尖部水平到尖部的间隔物厚度（10毫米）、从中间到尖部的直肠排除情况以及侧向性与50和60戈瑞相对生物效应（Gy[RBE]）直肠剂量相关（P = 4.1×10 - 0.046）。分离值与尖部（10毫米）和尖部（4毫米）的间隔物厚度密切相关（P = 1.1×10 - 1.8×10）。各组在10至60 Gy(RBE)时的直肠体积不同（P = 5.1×10 - 5.4×10）。在所有剂量水平下，第2组的直肠体积均小于第1组，但在30至50 Gy(RBE)剂量水平下，第3组的直肠体积小于第2组。
从前列腺中部到尖部的分离度、间隔物厚度、直肠排除情况以及水凝胶间隔物的侧向性影响直肠剂量的降低。通过在尾端和前列腺侧植入间隔物可进一步降低直肠剂量。
