Changing brachytherapy with MRI remnant-tumor segmentation and active-catheter placement

宫颈癌是一个世界性的公共卫生问题和重要的死亡原因，超过 每年有500,000名妇女确诊。局部晚期疾病妇女的最佳治疗方案 要求先进行外照射(EBRT)，然后进行近距离放射治疗。近距离放射治疗允许 通过间质导管向肿瘤内输送更大剂量的药物，这些导管被放置在残留的肿瘤中， 在EBRT中存活下来。这些导管的放置，里面放置了金属棒的中空塑料管 推挤身体组织，通常是在没有任何指导的情况下进行的，以及由于疏忽而引起的并发症 可能会导致植入正常组织(血管、直肠、膀胱)，而不是残留肿瘤。 磁共振引导的近距离放射治疗(MRBT)显著提高了存活率，减少了 不经意间辐射到邻近组织而引起的并发症。为了正确定位导管 为了计算辐射剂量，需要在MRBT之后进行CT检查。这延长了本已复杂和费力的工作- 密集手术，这也受累于不完善的方法来识别EBRT和 在MRBT之前。在MRBT前确定正常组织为残留肿瘤可能导致意外治疗 对健康组织进行辐射，会增加并发症。后遗症的MRI多参数识别 放射治疗残留肿瘤，结合磁共振所见的主动跟踪导管置入疾病 扫描，可以得到更精确的治疗量，以及更快和更准确的MRBT导管 放置，导致更好的结果和减少并发症。这应该会增加MRBT在 治疗宫颈癌，以及复发的子宫内膜癌、阴道癌、前列腺癌和其他癌症。 拟议的程序使用了几个新的工具：(A)绘制组织图的MRI序列 EBRT后盆腔的血流灌注、扩散、纤维化和氧合等参数分析 专家临床医生，并用于开发一种方法，以提供精细化的残余肿瘤地图；(B)一种新的主动- 放置在阴道中的封闭式MRI线圈，可将MRI扫描时间减少50%；(C)灵活的主动- 履带式金属导管，与新的Elekta Venzia敷贴器集成，提高了定位精度 和加速放置；以及(D)术中瞬时剂量图，其中导管位置在 放置过程中的任何时间都用来预测和指导临床医生的最佳下一步行动，例如 如改变当前的导管位置或增加更多的导管。总而言之，这些方法将最终达到 剂量优化的导管放置，将降低肿瘤复发和限制辐射副作用。 该项目是约翰霍普金斯大学和Elekta Inc.JHU Radiation的合作项目 肿瘤学家、放射学家、医学物理学家和核磁共振物理学家，以及一个专家小组 残存肿瘤，将与Elekta工程师共同开发具有广泛应用的创新平台 在放射肿瘤学方面。开发的工具在20名宫颈癌患者队列中得到了验证。

Cervical cancer is a worldwide public health problem and significant cause of mortality, with over 500,000 women diagnosed each year. Optimal curative treatment for women with locally advanced disease calls for treatment with external beam radiation (EBRT) followed by brachytherapy. Brachytherapy allows delivering larger dose into the tumor with interstitial catheters, which are placed into the residual tumors that survive EBRT. The placement of these catheters, hollow plastic tubes with metal rods placed inside for pushing through body tissue, is typically done without any guidance, and complications due to inadvertent insertion into normal tissues (blood vessels, rectum, bladder), rather than into residual tumor, may result. Magnetic resonance-guided brachytherapy (MRBT) has significantly improved survival and reduced complications caused by inadvertently radiating neighboring tissues. In order to locate the catheters properly and to calculate radiation dose, a CT is required after the MRBT. This lengthens an already complex and labor- intensive procedure, which also suffers from imperfect methods to identify residual tumor after EBRT and before MRBT. Identifying normal tissues as residual tumor before MRBT may result in inadvertent treatment with radiation of healthy tissues, which increases complications. MRI multi-parametric identification of post- EBRT residual tumor, combined with actively-tracked catheter placement into the disease as seen on MR scanning, can result in a more precise treatment volume, and faster and more accurate MRBT catheter placement, leading to better outcomes and reduced complications. This should increase the use of MRBT in treating cervical cancer, as well as recurrent endometrial, vaginal, prostate, and other cancers. The proposed procedure utilizes several novel tools: (a) MRI sequences that map the tissue parameters perfusion, diffusion, fibrosis and oxygenation in the post-EBRT pelvis, which are analyzed by expert clinicians, and used to develop a method for providing refined remnant tumor maps; (b) a novel active- obturator MRI coil which is placed in the vagina, that reduces MRI scan times by >50%; (c) flexible actively- tracked metallic catheters, integrated with the new Elekta Venezia applicator, improving localization precision and accelerating placement; and, (d) instantaneous intraoperative dose mapping, where catheter locations at any time during placement are used to predict and guide what the clinician's best next move should be, such as changing current catheter locations or adding more catheters. Together, these methods will culminate in dose-optimized catheter placements that will lower tumor recurrence and limit radiation side effects. This project is a collaboration between Johns Hopkins University and Elekta Inc. JHU radiation oncologists, radiologists, medical physicists and MRI physicists, along with a panel of experts in identifying remnant tumor, will work jointly with Elekta engineers to develop an innovative platform with broad applications in radiation oncology. The tools developed are validated in a 20-patient cohort of cervical cancer patients.