Howell R W, Rao D V, Sastry K S
Department of Radiology, University of Medicine and Dentistry of New Jersey, Newark 07103.
Med Phys. 1989 Jan-Feb;16(1):66-74. doi: 10.1118/1.596404.
In the context of radioimmunotherapy of cancer, there is a need for continued improvement of dosimetry of radionuclides localized in tumors. Current methods assume uniform distribution of radionuclides in the tumor despite experimental evidence indicating nonuniormity. We have developed a model in which nonuniform distribution of radioactivity in the tumor is taken into account. Spherically symmetric radionuclide distributions, depending linearly and exponentially on the radial position, are considered. Dose rate profiles in the tumor are calculated for potentially useful beta-emitting radionuclides, including 32P, 67Cu, 90Y, 111Ag, 131I, and 188Re, and for 193mPt, an emitter of conversion electrons and low-energy Auger electrons. For the radionuclide distributions investigated, high-energy beta emitters, such as 90Y, are most effective in treating large tumors (diameter, d greater than approximately 1 cm), whereas for small tumors (d approximately 1 mm), medium energy beta emitters such as 67Cu are better suited. Very small tumors (d less than 1 mm), and micrometastases are best handled with low-energy electron emitters such as 193mPt.
在癌症的放射免疫治疗背景下，需要持续改进肿瘤中定位的放射性核素的剂量测定法。尽管有实验证据表明放射性核素在肿瘤中的分布不均匀，但目前的方法仍假定其在肿瘤中呈均匀分布。我们已经开发了一个模型，该模型考虑了肿瘤中放射性的非均匀分布。考虑了呈球对称的放射性核素分布，其分别线性和指数地依赖于径向位置。针对包括32P、67Cu、90Y、111Ag、131I和188Re在内的潜在有用的β发射放射性核素，以及针对转换电子和低能俄歇电子发射体193mPt，计算了肿瘤中的剂量率分布。对于所研究的放射性核素分布，高能β发射体，如90Y，在治疗大肿瘤（直径d大于约1 cm）时最有效，而对于小肿瘤（d约1 mm），中等能量的β发射体如67Cu更适合。非常小的肿瘤（d小于1 mm）和微转移灶最好用低能电子发射体如193mPt来处理。
