Correcting kernel tilting and hardening in convolution/superposition dose calculations for clinical divergent and polychromatic photon beams.
Correcting kernel tilting and hardening in convolution/superposition dose calculations for clinical divergent and polychromatic photon beams.
复制标题
校正临床发散和多色光子束的卷积/叠加剂量计算中的核倾斜和硬化。
DOI：
10.1118/1.597960
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发表时间：
1997
期刊：
影响因子：
3.8
通讯作者：
E. McCullough
中科院分区：
文献类型：
--
作者：
H. Liu;T. Mackie;E. McCullough
为了解释临床发散和多色光子束，我们已经开发了卷积剂量计算算法的内核倾斜和内核硬化校正方法。新的校正方法通过蒙特卡罗模拟进行了验证。我们的内核倾斜和内核硬化校正方法的准确性和计算时间进行了比较，现有的方法，包括terma发散校正，剂量发散校正方法，和有效的平均内核方法，没有内核硬化校正。研究了10 x 10-40 x 40 cm 2治疗野（源到轴距离（SAD）处的野大小），源到源距离（SSD）为60、80和100 cm，光子能量为6、10和18 MV。结果表明，基于中心轴上沿着15 cm深度处的相对剂量误差，对于SSD大于80 cm的小于10 x 10 cm 2的射野，可以采用terma发散校正;采用附加核硬化校正的剂量发散校正可以减小剂量误差，可能比terma发散校正更适用。对于这两种方法，剂量误差随体模中的深度线性增加;由于明显低估半影剂量，15 cm深度处的90%等剂量线偏移约2%-5%的射野宽度。对于临床光子束，核硬化效应不如核倾斜效应显著。在沿中心轴沿着15 cm深度处，非硬化校正核的剂量误差小于2.0%，但随着射野尺寸和光子能量的减小，误差增大。当射束硬化更显著时，核硬化校正对于计算具有射束修改器（如楔形件）的射野中的剂量可能更重要。核倾斜校正和核硬化校正分别使计算时间增加约3倍和0.5-1倍。这可以通过对大多数临床治疗进行更准确的剂量计算来证明。
To account for clinical divergent and polychromatic photon beams, we have developed kernel tilting and kernel hardening correction methods for convolution dose calculation algorithms. The new correction methods were validated by Monte Carlo simulation. The accuracy and computation time of the our kernel tilting and kernel hardening correction methods were also compared to the existing approaches including terma divergence correction, dose divergence correction methods, and the effective mean kernel method with no kernel hardening correction. Treatment fields of 10 x 10-40 x 40 cm2 (field size at source to axis distance (SAD)) with source to source distances (SSDs) of 60, 80, and 100 cm, and photon energies of 6, 10, and 18 MV have been studied. Our results showed that based on the relative dose errors at a depth of 15 cm along the central axis, the terma divergence correction may be used for fields smaller than 10 x 10 cm2 with a SSD larger than 80 cm; the dose divergence correction with an additional kernel hardening correction can reduce dose error and may be more applicable than the terma divergence correction. For both these methods, the dose error increased linearly with the depth in the phantom; the 90% isodose lines at the depth of 15 cm were shifted by about 2%-5% of the field width due to significant underestimation of the penumbra dose. The kernel hardening effect was less prominent than the kernel tilting effect for clinical photon beams. The dose error by using nonhardening corrected kernel is less than 2.0% at a depth of 15 cm along the central axis, yet it increased with a smaller field size and lower photon energy. The kernel hardening correction could be more important to compute dose in the fields with beam modifiers such as wedges when beam hardening is more significant. The kernel tilting correction and kernel hardening correction increased computation time by about 3 times, and 0.5-1 times, respectively. This can be justified by more accurate dose calculations for the majority of clinical treatments.
影响因子：
3.8
作者：
ROGERS, DWO;FADDEGON, BA;MACKIE, TR
通讯作者：
MACKIE, TR
影响因子：
3.8
作者：
PAPANIKOLAOU, N;MACKIE, TR;RECKWERDT, P
通讯作者：
RECKWERDT, P
使用卷积计算非均匀介质中的光子剂量分布。
影响因子：
3.8
作者：
Boyer,AL;Mok,EC
通讯作者：
Mok,EC