Ferrous sulphate gels for determination of absorbed dose distributions using MRI technique: basic studies.
Ferrous sulphate gels for determination of absorbed dose distributions using MRI technique: basic studies.
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使用 MRI 技术测定吸收剂量分布的硫酸亚铁凝胶：基础研究。
DOI：
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发表时间：
1989
影响因子：
3.5
通讯作者：
S. Mattsson
中科院分区：
文献类型：
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作者：
Lars E. Olsson;J. Petersson;L. Ahlgren;S. Mattsson
已发现两种凝胶适合装载硫酸亚铁溶液。在这些软组织等效模型中，可以在临床使用的磁共振成像设备中测量照射后的吸收剂量分布。目前的研究是使用没有成像特性的 0.25 T NMR 分析仪进行的。硫酸亚铁溶液（相对于硫酸为 0.05 M）可以用 4% 明胶胶凝，得到剂量计，其响应与 0-40 Gy 区间内的吸收剂量线性相关（r = 0.998）。硫酸亚铁溶液也可以用 1% 琼脂糖胶凝，但必须用氧气吹扫该凝胶，才能在相同吸收剂量间隔内获得线性关系 (r = 0.997)。硫酸亚铁负载凝胶的灵敏度对于明胶和琼脂糖来说分别是普通剂量计溶液的 2.2 或 4.0 倍。由于凝胶背景测量的标准偏差高于剂量计溶液，因此两种凝胶和剂量计溶液的最小可检测吸收剂量大致相同，即 1.0 Gy。如果平均剂量率和每脉冲吸收剂量在放射治疗加速器通常使用的限度内，则负载硫酸亚铁的凝胶的灵敏度不依赖于剂量率。
Two gels have been found to be suitable to load with ferrous sulphate solution. In these soft tissue equivalent phantoms, the absorbed dose distribution can be measured after irradiation in clinically used MR imaging equipment. The present studies were carried out using a 0.25 T NMR analyser without imaging properties. A ferrous sulphate solution, 0.05 M with respect to sulphuric acid, can be gelled with 4% gelatin to give a dosemeter which has a response which is linearly correlated (r = 0.998) with the absorbed dose in the interval 0-40 Gy. Ferrous sulphate solution can also be gelled with 1% agarose, but this gel has to be purged with oxygen to obtain a linear relationship (r = 0.997) in the same absorbed dose interval. The ferrous sulphate loaded gels have a sensitivity which is a factor of 2.2 or 4.0 times higher for gelatin and agarose, respectively, than the ordinary dosemeter solution. Because the standard deviation of background measurements is higher for the gels than for the dosemeter solution, the minimum detectable absorbed dose is about the same, or 1.0 Gy, for the two gels and the dosemeter solution. The sensitivity of the ferrous sulphate loaded gels shows no dependence on dose rate if the mean dose rate and the absorbed dose per pulse are within the limits normally used by accelerators for radiotherapy.