Yoriyaz H, Stabin M G, dos Santos A
Instituto de Pesquisas Energéticas e Nucleares, Cidade Universitária, São Paulo, Brazil.
J Nucl Med. 2001 Apr;42(4):662-9.
This study was intended to verify the capability of the Monte Carlo MCNP-4B code to evaluate spatial dose distribution based on information gathered from CT or SPECT.
A new three-dimensional (3D) dose calculation approach for internal emitter use in radioimmunotherapy (RIT) was developed using the Monte Carlo MCNP-4B code as the photon and electron transport engine. It was shown that the MCNP-4B computer code can be used with voxel-based anatomic and physiologic data to provide 3D dose distributions.
This study showed that the MCNP-4B code can be used to develop a treatment planning system that will provide such information in a time manner, if dose reporting is suitably optimized. If each organ is divided into small regions where the average energy deposition is calculated with a typical volume of 0.4 cm(3), regional dose distributions can be provided with reasonable central processing unit times (on the order of 12-24 h on a 200-MHz personal computer or modest workstation). Further efforts to provide semiautomated region identification (segmentation) and improvement of marrow dose calculations are needed to supply a complete system for RIT. It is envisioned that all such efforts will continue to develop and that internal dose calculations may soon be brought to a similar level of accuracy, detail, and robustness as is commonly expected in external dose treatment planning.
For this study we developed a code with a user-friendly interface that works on several nuclear medicine imaging platforms and provides timely patient-specific dose information to the physician and medical physicist. Future therapy with internal emitters should use a 3D dose calculation approach, which represents a significant advance over dose information provided by the standard geometric phantoms used for more than 20 y (which permit reporting of only average organ doses for certain standardized individuals)
本研究旨在验证蒙特卡罗MCNP - 4B代码基于从CT或SPECT收集的信息评估空间剂量分布的能力。
使用蒙特卡罗MCNP - 4B代码作为光子和电子传输引擎，开发了一种用于放射免疫治疗（RIT）中内部发射体的新的三维（3D）剂量计算方法。结果表明，MCNP - 4B计算机代码可与基于体素的解剖和生理数据一起使用，以提供3D剂量分布。
本研究表明，如果剂量报告得到适当优化，MCNP - 4B代码可用于开发一个能及时提供此类信息的治疗计划系统。如果将每个器官划分为小区域，以0.4 cm³的典型体积计算平均能量沉积，则可以在合理的中央处理器时间内（在200 MHz个人计算机或普通工作站上约为12 - 24小时）提供区域剂量分布。需要进一步努力提供半自动区域识别（分割）并改进骨髓剂量计算，以提供一个完整的RIT系统。可以预见，所有这些努力将继续发展，并且内部剂量计算可能很快会达到与外部剂量治疗计划中通常预期的类似的准确性、细节和稳健性水平。
在本研究中，我们开发了一个具有用户友好界面的代码，该代码可在多个核医学成像平台上运行，并能及时为医生和医学物理学家提供患者特异性剂量信息。未来使用内部发射体的治疗应采用3D剂量计算方法，这相对于使用了20多年的标准几何体模所提供的剂量信息（仅允许报告某些标准化个体的平均器官剂量）有了显著进步。
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