Spinal Cord Tolerance to Radiosurgical Dose Delivery

脊柱肿瘤影响了大量的人，引起失能性疼痛、感觉和运动缺陷， 括约肌功能丧失和脊椎塌陷。图像引导立体定向放射外科的研究进展 技术已经使得能够以精确度和剂量照射脊柱和脊柱旁肿瘤 以前仅限于大脑的顺应性为个体对抗癌症创造了新的选择。 脊椎在一次分割中以非常高的剂量照射脊髓附近病变的机会 引起了人们对脊髓放射敏感性和脊髓病可能性的新关注。之甚少 关于脊髓对放射外科剂量输送的耐受性是已知的， 梯度导致仅一部分脊髓接收高剂量。因此，临床医生往往被迫 处方剂量远低于那些显示导致颅内病变控制率高的剂量。一 啮齿类动物的放射治疗模型表明，对于小体积和部分放射治疗， 脊髓照射和灵长类动物模型表明，脊髓在照射后经历了显著的修复， 标准的放疗过程，但没有研究结合这些因素的方式相关的临床 放射外科实践。提出了一项脊髓耐受性研究，该研究将包括从头和 接受脊柱SRS治疗的人通常经历的再治疗情况。具体来说，这项研究是 旨在确定：A）接受脊髓损伤治疗的猪中脊髓病的剂量相关发病率， 使用剂量率、射野大小和剂量的临床相关治疗参数的放射外科治疗 分布; B）接受脊柱放射外科手术的猪中脊髓病的剂量相关发病率 在完成脊柱标准临床放射方案后一年提供的治疗 转移（300 cGy × 10）;和C）如果3特斯拉磁共振成像和光谱学 对放射外科手术后生物过程的早期表达敏感，以便区分 可逆和不可逆的损害，并指出潜在的干预措施。广达将对数据进行分析 使用概率单位分析建立剂量效应曲线，并计算与50% 瘫痪的发生率。这项研究将提供必要的知识，最终将转化为脊柱 癌症患者接受最好的生存机会，无痛苦，高质量的生活，同时保持 非常低的致残副作用

Tumors of the spine affect a large number of people causing incapacitating pain, sensory and motor deficits, loss of sphincter function and vertebral collapse. Advances in image-guided stereotactic radiosurgery (SRS) techniques have enabled the irradiation of spinal and paraspinal neoplasms with an accuracy and dose conformality previously restricted to the brain creating new options for individuals fighting cancers of the spine. The opportunity to irradiate lesions adjacent to the spinal cord to very high doses in a single fraction has raised new concerns regarding the radiosensitivity of the cord and the potential for myelopathy. Little is known regarding the tolerance of the spinal cord to a radiosurgical dose delivery in which the steep dose gradients result in only a fraction of the cord receiving a high dose. Therefore, clinicians are often compelled to prescribe doses much lower than those shown to result in a high rate of control for intracranial lesions. A radiotherapy model in rodents suggests there is a profound dose-volume effect for small volume and partial cord irradiation and a primate model suggests the spinal cord undergoes significant repair following a standard course of radiotherapy but no study has combined these factors in a manner relevant to clinical radiosurgery practice. A spinal cord tolerance study is proposed that will incorporate both de novo and retreatment scenarios commonly experienced by humans treated with spinal SRS. Specifically, this study is intended to determine: A) the dose-related incidence of myelopathy in swine that receive a spinal radiosurgery treatment using clinically relevant treatment parameters of dose rate, field size and dose distribution; B) the dose related incidence of myelopathy in swine that receive a spinal radiosurgery treatment delivered one year following completion of a standard clinical radiation regimen for spinal metastases (300 cGy times 10);and C) if 3 Tesla magnetic resonance imaging and spectroscopy are sensitive to the early expression of post-radiosurgery biological processes so as to discriminate between reversible and irreversible damage and to indicate potential interventions. Quanta! data will be analyzed using probit analysis to establish dose-effect curves, and to calculate the doses associated with a 50% incidence of paralysis. This study will provide essential knowledge that will ultimately translate into spine cancer patients receiving the best chance for survival with a pain free, high quality of life while maintaining a very low level of disabling side effects.