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

宫颈癌是一个全球性的公共卫生问题，也是导致死亡的重要原因， 每年有50万妇女被诊断出患有乳腺癌。局部晚期疾病女性的最佳治疗方法 要求用外照射（EBRT）治疗，然后进行近距离放射治疗。近距离放射治疗允许 用间质导管将更大剂量的药物输送到肿瘤中， 在EBRT中幸存这些导管的放置，中空的塑料管与金属杆放置在里面， 通常在没有任何引导的情况下完成，并且由于疏忽而引起并发症。 可能导致插入正常组织（血管、直肠、膀胱）中，而不是插入残余肿瘤中。 磁共振引导近距离放射治疗（MRBT）显著提高了生存率， 由于无意中辐射邻近组织而引起的并发症。为了正确定位导管 并且为了计算辐射剂量，在MRBT之后需要CT。这将延长一个已经复杂和劳动- 强化手术，其也遭受不完善的方法来识别EBRT后的残留肿瘤， 在MRBT之前在MRBT前将正常组织识别为残留肿瘤可能导致治疗疏忽 对健康组织进行放射治疗，这会增加并发症。MRI多参数识别后 EBRT残留肿瘤，结合主动跟踪导管置入疾病，如MR所示 扫描，可以产生更精确的治疗体积，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。这将增加MRBT的使用， 治疗宫颈癌，以及复发性子宫内膜癌、阴道癌、前列腺癌和其他癌症。 所提出的程序利用几种新的工具：（a）MRI序列，映射组织 EBRT后骨盆的灌注、弥散、纤维化和氧合参数，通过 专家临床医生，并用于开发用于提供精确的残余肿瘤图的方法;（B）一种新的活性- 闭孔MRI线圈，放置在阴道中，减少MRI扫描时间>50%;（c）主动柔性- 跟踪金属导管，与新的Elekta Venezia施用器集成，提高定位精度 和加速放置;以及，（d）瞬时术中剂量分布，其中导管位置在 用于预测和指导临床医生的最佳下一步行动， 改变当前导管位置或添加更多导管。总之，这些方法将达到高潮， 剂量优化的导管放置，将降低肿瘤复发和限制辐射副作用。 这个项目是约翰霍普金斯大学和Elekta公司的合作项目。JHU辐射 肿瘤学家、放射科医生、医学物理学家和MRI物理学家，沿着一个专家小组， 将与Elekta工程师共同开发具有广泛应用的创新平台 放射肿瘤学开发的工具在20例宫颈癌患者队列中进行了验证。

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.