The treatment of solid tumors by alpha emitters released from 224Ra-loaded sources-internal dosimetry analysis
The treatment of solid tumors by alpha emitters released from 224Ra-loaded sources-internal dosimetry analysis
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DOI：
10.1088/0031-9155/55/4/020
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发表时间：
2010-02-21
影响因子：
3.5
通讯作者：
Kelson, I.
中科院分区：
文献类型：
--
作者：
Arazi, L.;Cooks, T.;Kelson, I.
扩散α发射体放射治疗（DART）是一种新型近距离放射治疗，可以通过α粒子治疗实体瘤。 DART 利用携带小活性镭 224 的植入源，不断释放到肿瘤中的氡 220、钋 216 和铅 212 原子，而镭 224 本身仍然固定在源上。释放的原子通过扩散和对流过程分散在肿瘤内部，通过它们的α发射，在每个源周围形成一个直径为几毫米的高剂量区域。 DART 的功效已在小鼠源性鳞状细胞癌和肺肿瘤的临床前研究中得到证实，该方法目前正在开发用于临床试验。这项工作依赖于生物动力学计算与内部剂量评估相结合，研究了由于 212 铅从肿瘤通过血液泄漏而输送到远处器官的剂量方面的 DART 安全性。研究发现，剂量限制器官是肾脏和红骨髓。假设肿瘤组织的典型源间距约为5毫米，典型的镭224活性密度为0.4-0.8 MBq g(-1)，预计可以治疗重达数百克的肿瘤，而不会达到任何器官的耐受剂量。
Diffusing alpha-emitters radiation therapy (DART) is a proposed new form of brachytherapy, allowing the treatment of solid tumors by alpha particles. DART utilizes implantable sources carrying small activities of radium-224, which continually release into the tumor radon-220, polonium-216 and lead-212 atoms, while radium-224 itself remains fixed to the source. The released atoms disperse inside the tumor by diffusive and convective processes, creating, through their alpha emissions, a high-dose region measuring several mm in diameter about each source. The efficacy of DART has been demonstrated in preclinical studies on mice-borne squamous cell carcinoma and lung tumors and the method is now being developed toward clinical trials. This work studies DART safety with respect to the dose delivered to distant organs as a result of lead-212 leakage from the tumor through the blood, relying on a biokinetic calculation coupled to internal dose assessments. It is found that the dose-limiting organs are the kidneys and red bone marrow. Assuming a typical source spacing of similar to 5 mm and a typical radium-224 activity density of 0.4-0.8 MBq g(-1) of tumor tissue, it is predicted that tumors weighing up to several hundred grams may be treated without reaching the tolerance dose in any organ.