Bohm T D, Mourtada F A, Das R K
Department of Medical Physics, University of Wisconsin-Madison, 53706, USA.
Med Phys. 2001 Aug;28(8):1770-5. doi: 10.1118/1.1384459.
Studies of intravascular brachytherapy to prevent restenosis following angioplasty have shown many promising results. Accurate dose rate tables based on detailed models of the brachytherapy sources are necessary for treatment planning. This work will present an away and along dose rate table for a 27 mm long catheter based 32P beta source. MD-55-2 radiochromic film has been exposed at five different depths (0.5 mm-4 mm) in a polystyrene phantom using a 27 mm long Guidant 32P beta source. The total dose to the active region of the film was determined using the absolute detector response of the MD-55-2 radiochromic film. The Monte Carlo code MCNP4B2 was also used to calculate the dose to the active region of the film using a detailed model of the source, encapsulation, and radiochromic film. The dose to film calculations showed good agreement with the measurements presented in this work with an average difference of 7%. The Monte Carlo calculations were also verified against previously published depth dose in water measurements determined using radiochromic film and plastic scintillator. The depth dose calculations in water showed good agreement with the previously published measurements with the calculations being about 2.5% lower than the film measurements and about 2.5% higher than the scintillator measurements. This work then uses the verified Monte Carlo code to present a dose rate table for the 32P intravascular beta source.
血管内近距离放射治疗预防血管成形术后再狭窄的研究已显示出许多有前景的结果。基于近距离放射治疗源详细模型的准确剂量率表对于治疗计划是必要的。这项工作将给出基于27毫米长导管的32Pβ源的轴向和侧向剂量率表。使用27毫米长的Guidant 32Pβ源，MD-55-2放射变色膜已在聚苯乙烯体模中的五个不同深度（0.5毫米至4毫米）处曝光。使用MD-55-2放射变色膜的绝对探测器响应确定膜活性区域的总剂量。蒙特卡罗代码MCNP4B2也用于使用源、封装和放射变色膜的详细模型计算膜活性区域的剂量。膜剂量计算与本工作中的测量结果显示出良好的一致性，平均差异为7%。蒙特卡罗计算还与先前发表的使用放射变色膜和塑料闪烁体确定的水中深度剂量测量结果进行了验证。水中深度剂量计算与先前发表的测量结果显示出良好的一致性，计算结果比膜测量结果低约2.5%，比闪烁体测量结果高约2.5%。然后，这项工作使用经过验证的蒙特卡罗代码给出32P血管内β源的剂量率表。
