A dosimetric comparison of copper and Cerrobend electron inserts.
A dosimetric comparison of copper and Cerrobend electron inserts.
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DOI：
10.1120/jacmp.v17i5.6282
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发表时间：
2016-09-08
影响因子：
2.1
通讯作者：
Hogstrom KR
中科院分区：
文献类型：
--
作者：
Rusk BD;Carver RL;Gibbons JP;Hogstrom KR
本工作旨在评价电子束治疗中使用铜孔插件与铅合金（Cerrobend）孔插件相比产生的剂量差异。具体而言，本研究检查了铜孔插件是否可以在临床上使用，使用铅合金孔插件测量的调试数据相同。铜内衬购自.decimal，LLC，匹配的铅合金Cerrobend内衬在内部构建，用于9种方形内衬区域尺寸（to）和5种施源器尺寸（to）的32种组合。在Varian Clinac 21 EX加速器上，使用水中电子二极管测量选定铜和Cerrobend插入物的百分比深度剂量和离轴相对剂量分布，用于一组施源器（）和能量（6、12、20 MeV），源-表面距离（SSD）为100和110 cm。在100 cm SSD和110 cm SSD的较小子集上，测量了所有射野尺寸-垫片组合和5种可用能量（）的剂量输出。使用这些数据，生成2D平面绝对剂量分布并进行比较。对于99%的点，一致性标准为最大剂量或1 mm的一致距离。射束剂量测定的伽马分析显示，96个衬垫尺寸、施源器、能量和SSD的组合中有94个在点的标准范围内。在射野外，与Cerrobend相比，铜插入物显示插入物下的韧致辐射剂量更少（在20 MeV和100 cm SSD下的最大差异为2.5%）。这种效应在大施源器与小射野尺寸组合的最高能量下最为突出，导致一些伽马分析失败。在磁场内部，与Cerrobend相比，更多的电子从铜的准直器边缘散射，导致在浅深度处铜的磁场边缘处的剂量增加（在20 MeV和100 cm SSD处最大增加为1%）。剂量差异随着SSD的增加而减小，在110 cm SSD处没有伽马失效。任何能量下射野大小的测量，或能量下小射野的测量（），显示超过99%的点的剂量差异小于。所有比较标准失败的区域均来自铜插件下的较低场外剂量，这是由于韧致辐射产生减少，这在临床上有利于减少计划治疗体积外健康组织的剂量。所有射野尺寸-施源器尺寸-能量组合100%通过标准。因此，临床上可接受使用Cerrobend插件测量剂量分布的铜插件进行治疗计划剂量计算和监测单元计算。PACS编号：87.56.jk
The purpose of this work was to evaluate differences in dose resulting from the use of copper aperture inserts compared to lead‐alloy (Cerrobend) aperture inserts for electron beam therapy. Specifically, this study examines if copper aperture inserts can be used clinically with the same commissioning data measured using lead‐alloy aperture inserts. The copper inserts were acquired from .decimal, LLC and matching lead‐alloy, Cerrobend inserts were constructed in‐house for 32 combinations of nine square insert field sizes ( to ) and five applicator sizes ( to ). Percent depth‐dose and off‐axis relative dose profiles were measured using an electron diode in water for select copper and Cerrobend inserts for a subset of applicators () and energies (6, 12, 20 MeV) at 100 and 110 cm source‐to‐surface distances (SSD) on a Varian Clinac 21EX accelerator. Dose outputs were measured for all field size‐insert combinations and five available energies () at 100 cm SSD and for a smaller subset at 110 cm SSD. Using these data, 2D planar absolute dose distributions were generated and compared. Criteria for agreement were of maximum dose or 1 mm distance‐to‐agreement for 99% of points. A gamma analysis of the beam dosimetry showed 94 of 96 combinations of insert size, applicator, energy, and SSD were within the criteria for of points. Outside the field, copper inserts showed less bremsstrahlung dose under the insert compared to Cerrobend (greatest difference was 2.5% at 20 MeV and 100 cm SSD). This effect was most prominent at the highest energies for combinations of large applicators with small field sizes, causing some gamma analysis failures. Inside the field, more electrons scattered from the collimator edge of copper compared to Cerrobend, resulting in an increased dose at the field edge for copper at shallow depths (greatest increase was 1% at 20 MeV and 100 cm SSD). Dose differences decreased as the SSD increased, with no gamma failures at 110 cm SSD. Inserts for field sizes at any energy, or for small fields () at energies , showed dosimetric differences less than for more than 99% of points. All areas of comparison criteria failures were from lower out‐of‐field dose under copper inserts due to a reduction in bremsstrahlung production, which is clinically beneficial in reducing dose to healthy tissue outside of the planned treatment volume. All field size‐applicator size‐energy combinations passed criteria for 100% of points. Therefore, it should be clinically acceptable to utilize copper insets with dose distributions measured with Cerrobend inserts for treatment planning dose calculations and monitor unit calculations. PACS number(s): 87.56.jk
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DOI：
10.3109/02841868509134368
发表时间：
1985-01-01
期刊：
ACTA RADIOLOGICA ONCOLOGY
影响因子：
--
作者：
RIKNER, G
通讯作者：
RIKNER, G
影响因子：
3.8
作者：
Almond, PR;Biggs, PJ;Rogers, DWO
通讯作者：
Rogers, DWO
影响因子：
3.5
作者：
Gauer, T.;Sokoll, J.;Schmidt, R.
通讯作者：
Schmidt, R.
影响因子：
3.8
作者：
TENHAKEN, RK;FRAASS, BA;JOST, RJ
通讯作者：
JOST, RJ
DOI：
10.3109/02841868009130153
发表时间：
1980-01-01
期刊：
ACTA RADIOLOGICA ONCOLOGY
影响因子：
--
作者：
LAX, I;BRAHME, A
通讯作者：
BRAHME, A