玻璃体替代物对碘125辐射的衰减在葡萄膜黑色素瘤治疗中的应用

Attenuation of iodine 125 radiation with vitreous substitutes in the treatment of uveal melanoma.

作者信息

Oliver Scott C N, Leu Min Y, DeMarco John J, Chow Philip E, Lee Steve P, McCannel Tara A

机构信息

Department of Ophthalmology, Jules Stein Eye Institute, University of California-Los Angeles, 100 Stein Plaza, Los Angeles, CA 90095, USA.

出版信息

Arch Ophthalmol. 2010 Jul;128(7):888-93. doi: 10.1001/archophthalmol.2010.117.

DOI:10.1001/archophthalmol.2010.117

PMID:20625051

Abstract

OBJECTIVE

To demonstrate attenuation of radiation from iodine 125 ((125)I) to intraocular structures using liquid vitreous substitutes.

METHODS

Four candidate vitreous substitutes were tested for attenuation using empirical measurement and theoretical calculation. In vitro and ex vivo cadaveric dosimetry measurements were obtained with lithium fluoride thermoluminescent dosimeters to demonstrate the attenuation effect of vitreous substitution during (125)I simulated plaque brachytherapy. Theoretical dosimetry calculations were based on Monte Carlo simulation.

RESULTS

In a cylindrical phantom at a 17-mm depth, liquid vitreous substitutes as compared with saline showed significant reduction of radiation penetration (48% for 1000-centistoke [cSt] silicone oil [polydimethyl-n-siloxane], 47% for 5000-cSt silicone oil [polydimethyl-n-siloxane], 40% for heavy oil [perfluorohexyloctane/polydimethyl-n-siloxane], and 35% for perfluorocarbon liquid [perfluoro-n-octane]). Human cadaveric ex vivo measurements demonstrated a 1000-cSt silicone oil to saline dose ratio of 35%, 52%, 55%, and 48% at arc lengths of 7.6, 10.6, 22.3, and 28.6 mm from the plaque edge, respectively, along the surface of the globe. Monte Carlo simulation of a human globe projected attenuation as high as 57% using 1000-cSt silicone oil.

CONCLUSIONS

Intraocular vitreous substitutes including silicone oil, heavy oil, and perfluorocarbon liquid attenuate the radiation dose from (125)I. Cadaveric ex vivo measurements and Monte Carlo simulation both demonstrate radiation attenuation using 1000-cSt silicone oil at distances corresponding to vital ocular structures. Clinical Relevance Attenuation of radiation with silicone oil endotamponade in the treatment of uveal melanoma may significantly reduce radiation-induced injury to vital ocular structures.

摘要

目的

使用液态玻璃体替代物来证明碘125（¹²⁵I）对眼内结构的辐射衰减情况。

方法

通过经验测量和理论计算对四种候选玻璃体替代物的衰减情况进行测试。使用氟化锂热释光剂量计进行体外和离体尸体剂量测定，以证明在¹²⁵I模拟敷贴近距离放射治疗期间玻璃体替代的衰减效果。理论剂量计算基于蒙特卡洛模拟。

结果

在深度为17毫米的圆柱形模型中，与盐水相比，液态玻璃体替代物显示出辐射穿透的显著降低（1000厘沲[cSt]硅油[聚二甲基-n-硅氧烷]为48%，5000-cSt硅油[聚二甲基-n-硅氧烷]为47%，重油[全氟己基辛烷/聚二甲基-n-硅氧烷]为40%，全氟化碳液体[全氟-n-辛烷]为35%）。人体尸体离体测量显示，在距敷贴边缘7.6、10.6、22.3和28.6毫米的弧长处，沿着眼球表面，1000-cSt硅油与盐水的剂量比分别为35%、52%、55%和48%。使用1000-cSt硅油对人体眼球进行蒙特卡洛模拟预测的衰减高达57%。