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

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。碘-131标记放射免疫治疗（RIT）在非霍奇金淋巴瘤（NHL）的治疗中显示出巨大的前景。为了实现放射性核素治疗的个体化，有必要建立可靠的靶组织剂量-反应关系和正常组织剂量-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不存在或相当弱的关系。缺乏更好的相关性可能是由于迄今为止使用的吸收剂量估计方法不准确。这保证了努力开发和评价基于成像的剂量测定的高度准确的方法。这是一项前瞻性初步研究，旨在评价新型SPECT-CT集成系统在接受I-131托西莫单抗（Bexaar）放射免疫治疗（RIT）的非霍奇金淋巴瘤患者中用于基于成像的剂量测定的潜在价值。我们的目的是确定并行SPECT-CT成像的价值，在精确的解剖定位区域异常放射性示踪剂活动相比，平面动脉造影和传统的SPECT。SPECT-CT图像将被用来进行高度准确的患者特异性三维剂量测定肿瘤和骨髓使用计算机算法最近实施的我们的小组。计划接受Bexaar治疗的5例年龄超过21岁的患者，包括所有性别和种族，将被要求在示踪剂和/或Bexaar治疗给药后自愿在新SPECT-CT系统上进行3至6次扫描。成像基于作为RIT治疗一部分给予的放射性，由于拟定研究的研究方面，患者将不会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，则可在未来用于大量受试者，以建立剂量-反应和剂量-毒性关系。这种关系的建立和前瞻性地进行基于高度精确成像的剂量测定的能力，将允许医生在未来以逐个患者为基础定制治疗方案，以向肿瘤提供最佳剂量，同时避免对关键器官的毒性。高度准确的骨髓剂量测定也可以允许纳入目前被排除在这种治疗之外的其他患者，因为目前的标准是他们的骨髓受累< 25%。

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.