The efficacy of synthetic polymers as hydrogel phantoms for radiation therapy and dosimetry has been investigated for photon and charged particle (electron, proton and alpha particle) interactions. Tissue equivalence has been studied in terms of photon mass energy-absorption coefficients, KERMA (kinetic energy released per unit mass), equivalent atomic number and energy absorption build-up factors, relative to human tissues (skin, soft tissue, cortical bone and skeletal muscle), in the energy range 0.015-15 MeV. For charged particle interactions, ratio of effective atomic number is examined for tissue-equivalence in the energy region of 10 keV-1 GeV. Well established theoretical formulations are used for computation of photon mass-energy absorption effective atomic number, electron density and KERMA. Five-parameter geometric progression (G-P) fitting approximation is used to compute the values of energy absorption build-up factors. Effective atomic number for charged particle interaction is determined using logarithmic interpolation method. Using the analytical methodology, it has been revealed that all the selected synthetic polymers have good tissue-equivalence relative to all tissue except cortical bone. In particular, polyglycolic acid (PGA) and poly-lactic-co-glycolic acid (PLGA) prove to be best substitute material for photon interactions. On the other hand, % difference between effective atomic number for charged particle relative to human tissues is found least for polyethylene glycol (PEG) demonstrating adequate tissue-equivalence. Therefore, the present study is expected to be useful to choose most appropriate phantom material for radiation therapy.

中文翻译：

---

合成聚合物水凝胶作为放射治疗和剂量测定中潜在的组织模型

已经研究了合成聚合物作为用于放射治疗和剂量测定的水凝胶体模的功效，用于光子和带电粒子（电子、质子和 α 粒子）相互作用。组织等效性已在光子质量能量吸收系数、KERMA（每单位质量释放的动能）、等效原子序数和能量吸收累积因子方面进行了研究，相对于人体组织（皮肤、软组织、皮质骨和骨骼）肌肉），能量范围为 0.015-15 MeV。对于带电粒子相互作用，在 10 keV-1 GeV 的能量范围内检查有效原子序数比的组织等效性。完善的理论公式用于计算光子质量-能量吸收有效原子序数、电子密度和 KERMA。五参数几何级数 (GP) 拟合近似用于计算能量吸收累积因子的值。带电粒子相互作用的有效原子序数是使用对数插值法确定的。使用分析方法，表明所有选定的合成聚合物相对于除皮质骨以外的所有组织都具有良好的组织等效性。特别是，聚乙醇酸 (PGA) 和聚乳酸-乙醇酸共聚物 (PLGA) 被证明是光子相互作用的最佳替代材料。另一方面，对于证明足够的组织等效性的聚乙二醇 (PEG)，发现带电粒子相对于人体组织的有效原子序数之间的百分比差异最小。所以，