回归拟合巨电压深度剂量曲线,以确定放射治疗中的材料相对电子密度
Anthony S Karl1, Jared G Steel2, George B Warr3
1Mid North Coast Cancer Institute Coffs Harbour, Mid North Local Health District, Coffs Harbour Health Campus, Coffs Harbour, NSW, 2450, Australia. anthony.karl@health.nsw.gov.au.
Physical and engineering sciences in medicine
|September 21, 2023
概括
一种新方法使用测量剂量数据准确确定放射治疗材料的相对电子密度 (RED). 这种方法提高了对CT扫描的准确性,特别是对于临床环境中的新材料和高Z组件.
科学领域:
- 医学物理 医学物理
- 放射治疗剂量计 放射治疗剂量计
- 材料科学 材料科学 材料科学
背景情况:
- 相对电子密度 (RED) 对于放射治疗剂量测量和治疗规划至关重要,与单独的质量密度相比,它提供了优越的放射性特性描述.
- 目前的RED测定依赖于CT Hounsfield Units (HU),但CT和LINAC光束之间的光谱差异可能会影响精度,特别是在新材料或高Z元素的情况下.
- 现有方法面临的挑战是材料偏离了典型的生物原子比或含有高原子数 (高-Z) 组件.
研究的目的:
- 实验性地实施和验证一种新的电子密度等效路径长度 (eEPL) 方法,用于在临床光束频谱内直接确定RED材料.
- 与标准CT衍生RED和制造商规格相比,评估这种新方法的准确性和局限性.
- 为放射治疗中未知的材料提供实用且强大的表征,特别是那些怀疑含有高Z成分的材料.
主要方法:
- 对各种材料的测量百分比剂量深度 (PDD) 曲线与参考PDD曲线 (水) 进行了回归.
- 从PDD回归计算推断的原子数与原子重量比 (Z/A).
- 通过将推断的Z/A与材料的物理密度相结合来确定RED.
主要成果:
- 通过PDD回归方法,获得了与制造商数据一致的RED值,以及在0.9至1.15RED范围内 (软组织等效) 的材料的CT衍生值.
- 在这个范围之外,推断的Z/A变得不切实际,表明eEPL模型对非软组织材料的假设的局限性.
- 该方法在有效的红色范围内证明了材料的稳定性和实用性.
结论:
- 实验性eEPL方法为在放射治疗中确定RED提供了有效和实用的方法,特别是对于软组织等价材料.
- 这种技术比CT衍生的RED提供了潜在的改进,特别是当高Z材料存在时.
- 可能需要对eEPL模型进行进一步的改进,以使其准确度超出目前软组织有效范围.
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