University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
J Xray Sci Technol. 2011;19(3):345-53. doi: 10.3233/XST-2011-0298.
Radiation therapy using antiprotons is a potential interesting future modality. Energetic antiprotons penetrate matter with almost near identical stopping powers and radio biological effectiveness (RBE) as protons in the region well before the Bragg peak region. When the antiprotons come to rest at or near the Bragg peak, they annihilate releasing almost 2 GeV per annihilation. Most of the energy is carried away on the average by 4 to 5 energetic pi mesons. The annihilations lead to roughly a doubling of physical dose with additional increase due to RBE in the Bragg peak region. This study was undertaken in order to assess the effect of the products of antiproton annihilations on depth dose profiles through MCNPX simulations. Beams of protons and antiprotons with varying energies and field sizes were used in the simulations. In our study, for 126 MeV beam, the peak to entrance (P/E) dose ratios of 4.9 for protons and 8.9 for antiprotons were found which gave the antiproton/proton P/E dose ratio equals to 1.8. This is in excellent agreement with the previous result obtained with FLUKA simulations.
使用反质子进行放射治疗是一种很有前途的未来治疗模式。在布拉格峰区域之前的区域，反质子的能量几乎与质子的阻止能力和放射生物学效应（RBE）完全相同，因此可以穿透物质。当反质子在布拉格峰处或附近静止时，它们会湮灭，每次湮灭释放近 2 吉电子伏特的能量。平均而言，大约有 4 到 5 个高能π介子带走了大部分能量。湮灭导致物理剂量增加约一倍，并且由于布拉格峰区域的 RBE 进一步增加。本研究旨在通过 MCNPX 模拟评估反质子湮灭产物对深度剂量分布的影响。在模拟中使用了不同能量和射野大小的质子和反质子束。在我们的研究中，对于 126 MeV 的束流，质子的峰到入口（P/E）剂量比为 4.9，反质子的 P/E 剂量比为 8.9，这使得反质子/质子的 P/E 剂量比为 1.8。这与使用 FLUKA 模拟得到的先前结果非常吻合。
