Hill R, Holloway L, Baldock C
South Western Sydney Cancer Services, Liverpool Hospital, Elizabeth Street, Liverpool, NSW 2170, Australia.
Phys Med Biol. 2005 Nov 7;50(21):N331-44. doi: 10.1088/0031-9155/50/21/N06. Epub 2005 Oct 19.
Solid phantoms are widely used in radiation therapy for both relative and reference dosimetry. Two water equivalent phantoms, RMI-457 Solid Water and Plastic Water, were evaluated for use in kilovoltage x-ray dosimetry in the energy range from 75 to 300 kVp. Relative and reference dosimetry measurements were performed in the solid phantoms and compared with water. The results indicate that RMI-457 Solid Water could be used for output factor determination for all energies tested and the measurement of percentage depth doses for the 300 kVp x-ray beam, with data agreeing to within 1%, compared to the same measurements in water. For the same criteria, Plastic Water could only be used for output factor determination of the 300 kVp x-ray beam. The superior agreement of the calculated mass-energy absorption coefficients for Solid Water and water, as compared to Plastic Water and water was consistent with the experimental results. Reference dosimetry is not recommended with the solid phantoms for the energies studied due to the lack of published correction factors. It is recommended that any solid phantom be tested by comparison with water in the same manner before being used for the dosimetry of kilovoltage x-ray beams.
固体模体在放射治疗的相对剂量测定和参考剂量测定中都有广泛应用。对两种水等效模体，即RMI - 457固体水模体和塑料水模体，进行了评估，以确定其在75至300 kVp能量范围内的千伏级X射线剂量测定中的适用性。在固体模体中进行了相对剂量测定和参考剂量测定，并与水的测定结果进行了比较。结果表明，RMI - 457固体水模体可用于所有测试能量下的输出因子测定以及300 kVp X射线束的百分深度剂量测量，与在水中进行的相同测量相比，数据一致性在1%以内。对于相同标准，塑料水模体仅可用于300 kVp X射线束的输出因子测定。与塑料水模体和水相比，固体水模体和水的计算质能吸收系数的更高一致性与实验结果相符。由于缺乏已发表的校正因子，不建议在所研究的能量下使用固体模体进行参考剂量测定。建议在将任何固体模体用于千伏级X射线束剂量测定之前，先以相同方式与水进行比较测试。
