Evaluation of w values for carbon beams in air, using a graphite calorimeter
Evaluation of w values for carbon beams in air, using a graphite calorimeter
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使用石墨热量计评估空气中碳梁的 w 值
DOI：
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发表时间：
2009
影响因子：
3.5
通讯作者：
Kyoko Abe
中科院分区：
文献类型：
--
作者：
M. Sakama;T. Kanai;A. Fukumura;Kyoko Abe
尽管最近在碳疗法方面取得了进展，但尚未获得物理数据的准确值，例如空气中的w值或电离室剂量测定的阻止功率比。用石墨量热计得到的石墨吸收剂量与使用电离室按照IAEA协议得到的石墨吸收剂量进行比较，以评估135，290，400和430 MeV/n单能碳束在空气中的w值。使用两个圆柱形腔室（PTW 30001型和PTW 30011型，Farmer）和两个平面平行腔室（PTW 23343型，Markus和PTW 34001型，鲁什），通过石墨吸收剂量和暴露于60 Co光子束进行校准。与我们的量热计测量结果的比较表明，使用电离室，在该实验能量范围内，石墨的吸收剂量低2-6%，并且使用这些电离室类型和校准方法。在治疗能量范围内，碳束在空气中的w值表示轻微的能量依赖性;然而，由于电离室的大的不确定性和未知的扰动因素，我们假设这些值在实际应用中是恒定的。在本研究中使用的能量范围内，碳束在空气中的w值估计为35.72 J C−1 ± 1.5%。这个值比IAEA TRS 398推荐的重离子束的值大3.5%。利用该估算结果，碳束中的水吸收剂量将增加相同的量。
Despite recent progress in carbon therapy, accurate values for physical data such as the w value in air or stopping power ratios for ionization chamber dosimetry have not been obtained. The absorbed dose to graphite obtained with the graphite calorimeter was compared with that obtained using the ionization chambers following the IAEA protocol in order to evaluate the w values in air for mono-energetic carbon beams of 135, 290, 400 and 430 MeV/n. Two cylindrical chambers (PTW type 30001 and PTW type 30011, Farmer) and two plane-parallel chambers (PTW type 23343, Markus and PTW type 34001, Roos) calibrated by the absorbed dose to graphite and exposure to the 60Co photon beam were used. The comparisons to our calorimeter measurements revealed that, using the ionization chambers, the absorbed dose to graphite comes out low by 2–6% in this experimental energy range and with these chamber types and calibration methods. In the therapeutic energy range, the w values in air for carbon beams indicated a slight energy dependence; we, however, assumed these values to be constant for practical use because of the large uncertainty and unknown perturbation factors of the ionization chambers. The w values in air of the carbon beams were evaluated to be 35.72 J C−1 ± 1.5% in the energy range used in this study. This value is 3.5% larger than that recommended by the IAEA TRS 398 for heavy-ion beams. Using this evaluated result, the absorbed dose to water in the carbon beams would be increased by the same amount.
A-150 塑料和石墨对于低能质子的热缺陷。
影响因子：
3.5
作者：
Schulz,RJ;Venkataramanan,N;Huq,MS
通讯作者：
Huq,MS