POST-TRACER AND POST-THERAPY IMAGING USING A NEW SPECT-CT INTEGRATED SYSTEM FOR

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。~(131)I标记的放射免疫疗法在非霍奇金S淋巴瘤的治疗中显示出巨大的应用前景。为了在放射性核素治疗的个体化治疗计划方面取得进展，有必要建立可靠的靶组织剂量-反应关系和正常组织的剂量-毒性关系。到目前为止，大多数临床I-131放射性核素治疗研究表明，辐射吸收剂量与肿瘤反应或关键器官毒性之间没有或相当弱的关系。缺乏更好的相关性可能是由于迄今使用的吸收剂量估计方法不准确所致。这就需要努力开发和评估基于成像的高精度剂量学方法。这是一项前瞻性的先导性研究，评估了一种新的SPECT-CT集成系统在接受I-131 Tositumomab(Bexaar)放射免疫疗法(RIT)治疗的非霍奇金淋巴瘤患者中基于成像的剂量测定的潜在价值。我们的目标是确定与平面核素扫描和常规SPECT相比，同步SPECT-CT成像在放射性示踪剂异常区域的精确解剖定位中的价值。SPECT-CT图像将用于使用我们团队最近实施的计算机算法在肿瘤和骨髓中进行高精度的患者特定三维剂量测量。计划接受Bexaar治疗的5名21岁以上的患者，无论男女，所有民族和种族，将被要求在示踪剂和/或Bexaar治疗后，自愿在新的SPECT-CT系统上进行3至6次扫描。成像是基于作为RIT治疗的一部分进行的放射性，由于拟议的研究方面的原因，患者将不会被注射任何额外的放射性。如果本项目确定了使用新系统进行高精度剂量测定的可行性，它可以在未来用于大量受试者，以建立剂量-反应和剂量-毒性关系。这种关系的建立以及前瞻性地进行基于高精度成像的剂量测定的能力，将使医生将来能够根据患者的不同定制治疗方案，以向肿瘤提供最佳剂量，同时避免对关键器官的毒性。高精度的骨髓剂量学也可以将目前因骨髓受累25%的患者排除在治疗范围之外的其他患者包括在内。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. I-131 labeled radioimmunotherapy (RIT) is showing great promise in the treatment of non-Hodgkin s lymphoma (NHL). To make advances towards individualized treatment planning in radionuclide therapy, it is necessary to establish reliable dose-response relationships for target tissue and dose-toxicity relationships for normal tissue. Thus far, most clinical I-131 radionuclide therapy studies have shown an absent or rather weak relationship between radiation absorbed dose and tumor response or critical organ toxicity. The lack of better correlation is possibly due to inaccuracies in absorbed dose estimation methods used thus far. This warrants the effort towards developing and evaluating highly accurate methods for imaging based dosimetry. This is a prospective pilot study evaluating the potential value of a new SPECT-CT integrated system for imaging based dosimetry in Non-Hodgkins lymphoma patients treated with I-131 tositumomab (Bexaar) radioimmunotherapy (RIT). We aim to determine the value of concurrent SPECT-CT imaging in precise anatomic localization of areas of abnormal radiotracer activity compared to planar scintigraphy and conventional SPECT. The SPECT-CT images will be used to carry out highly accurate patient specific 3-dimensional dosimetry in tumors and bone marrow using a computer algorithm recently implemented by our group. Five patients over 21 years of age of both genders and all ethnic and racial groups who are scheduled to undergo the Bexaar treatment will be asked to volunteer for between 3 to 6 scans on the new SPECT-CT system following the tracer and/or the therapy administration of Bexaar. The imaging is based on the radioactivity that is administered as part of the RIT treatment and the patient will not be injected with any additional radioactivity due to the research aspect of the proposed study. If the feasibility of using the new system for highly accurate dosimetry is established by the present project, it can be used in the future with a large number of subjects to establish dose-response and dose-toxicity relationships. Establishment of such relationships and the capability to carry out highly accurate imaging based dosimetry prospectively, will allow physicians in the future to tailor the treatment regimen on a patient-by-patient basis to deliver the optimum dose to the tumor while avoiding toxicity to critical organs. Highly accurate bone marrow dosimetry may also allow for the inclusion of additional patients who are presently excluded from this treatment because of the present criteria that they have < 25% bone marrow involvement.