LINEAR PD SOURCES FOR PROSTATE BRACHYTHERAPY

每年有超过20万的新患者罹患前列腺癌，其中非裔美国人的比例格外高，每年有41800人死于前列腺癌。近距离放射治疗是一种有效的前列腺癌治疗方法，(2)并且被越来越多的患者所选择。当前一代的近距离治疗种子包括125I或（103）Pd封装在钛壳。每个种子被设计成类似于具有各向同性分布的点源。在现实中，剂量各向异性高达60%(3)。种子通常不能精确地传递，最终会错位，并且容易迁移，导致对肿瘤的剂量可能不足。制造种子的方法简陋、效率低、劳动密集、成本高。第二阶段的申请扩展了在线性源的生产、评估和剂量学方面非常成功的工作：源制造将扩大规模；将采用新的交付系统；电线的剂量测定将扩大到包括剂量图谱和改进的治疗计划”。建立电线与种子等效性所需的信息将提交给FDA；线性源的安全性将在动物模型和临床研究中进行评估。拟议的商业应用：近距离治疗前列腺癌的市场渗透率预计将在5年内从目前的10-15%增加到50%以上。(4)间质性近距离植入种子治疗是FDA批准的，被广泛接受，并被医疗保险和其他报销计划覆盖。本文提出的进一步发展的线性源是相容的，但在许多方面优于种子。通过在临床环境中证明这种优于种子的优势，再加上预期的经济优势，线性来源的早期商业成功将很容易确立。随着时间的推移，线性光源有望在前列腺近距离治疗市场上取代种子。

Prostate cancer afflicts over 200,000 new patients, with a disproportionately large number of African-Americans, and causes 41,800 deaths(1) each year. Brachytherapy is an effective process for prostate cancer treatment,(2) and is being selected by a rapidly increasing proportion of patients. Current generation brachytherapy seeds consist either of 125I or (103)Pd encapsulated in titanium shells. Each seed is designed to resemble a point source with an isotropic distribution. In reality, the dose anisotropy is as much as 60%(3). The seeds are often not delivered with precision, end up misaligned, and are subject to migration, leading to the possibility of inadequate dose to the tumor. The method of manufacturing seeds is rudimentary, inefficient, labor intensive, and costly. This Phase II application expands the highly successful work on the production, evaluation, and dosimetry of linear sources: source manufacturing will be scaled up; a new delivery system will be introduced; the dosimetry of the wires will be expanded to include a dose atlas and improved treatment planning". The information necessary to establish equivalence of the wires to seeds will be submitted to the FDA; the safety of the linear sources will be evaluated in an animal model and in a clinical study. PROPOSED COMMERCIAL APPLICATIONS: Penetration of the market for the brachytherapy modality for treatment of prostate cancer is expected to increase from the current 10-15% to over 50% in 5 years.(4) Interstitial brachytherapy by placement of seeds is FDA approved, well accepted, and covered by Medicare and other reimbursement plans. The linear sources proposed here for further development are compatible, yet superior in many ways to seeds. By proving this superiority to seeds in a clinical setting, together with the expected economic advantages, early commercial success of the linear sources will readily be established. In time, the linear sources are expected to replace seeds in the prostate brachytherapy market.