Direct Charged-Particle Imaging System Using an Ultra-Thin Phosphor: Physical Characterization and Dynamic Applications.

Imaging ß rays in vivo will help to advance microdosimetry and radiopharmaceutical development. In an earlier paper [1], we reported a newly developed system capable of directly imaging high-energy electron emissions in small animals in vivo. In this paper, we have thoroughly characterized the performance of the system. We have measured the sensitivity and detectability and the spatial resolution at various magnifications, as well as the linearity of the system. The system has also demonstrated the capability of directly detecting conversion electrons and positrons as well as ß rays. The system has been applied to dynamically image spatiotemporal (18)F-Fluorodeoxyglucose (FDG) uptake distributions in xenograft small tumors in dorsal window chambers on mice in vivo. Heterogeneity in FDG uptake in millimeter-sized tumors has been observed.

Direct imaging of radionuclide-produced electrons and positrons with an ultrathin phosphor.

UNLABELLED: Current electron detectors are either unable to image in vivo or lack sufficient spatial resolution because of electron scattering in thick detector materials. This study was aimed at developing a sensitive high-resolution system capable of detecting electron-emitting isotopes in vivo. METHODS: The system uses a lens-coupled charge-coupled-device camera to capture the scintillation light excited by an electron-emitting object near an ultrathin phosphor. The spatial resolution and sensitivity of the system were measured with a 3.7-kBq (90)Y/(90)Sr beta-source and a 70-microm resin bead labeled with (99m)Tc. Finally, we imaged the (99m)Tc-pertechnetate concentration in the mandibular gland of a mouse in vivo. RESULTS: Useful images were obtained with only a few hundred emitted beta particles from the (90)Y/(90)Sr source or conversion electrons from the (99m)Tc bead source. The in vivo image showed a clear profile of the mandibular gland and many fine details with exposures of as low as 30 s. All measurements were consistent with a spatial resolution of about 50 microm, corresponding to 2.5 detector pixels with the current camera. CONCLUSION: Our new electron-imaging system can image electron-emitting isotope distributions at high resolution and sensitivity. The system is useful for in vivo imaging of small animals and small, exposed regions on humans. The ability to image beta particles, positrons, and conversion electrons makes the system applicable to most isotopes.

Combination therapy for non-Hodgkin's lymphoma: an opportunity for pharmaceutical care in a specialty practice.

OBJECTIVE: To describe the application of pharmaceutical care practices in the administration of new therapeutic radiopharmaceuticals used in the treatment of non-Hodgkin's lymphoma (NHL). PRACTICE DESCRIPTION: At the Antibody Labeling Facility at the University of Nebraska Medical Center, the nuclear pharmacist provides support in the formulation, preparation, and quality testing of radiopharmaceuticals. The nuclear pharmacist also provides direct patient care by assisting in the administration of radiopharmaceuticals, monitoring patients during their infusions, and counseling patients on radioimmunotherapy and radiation safety. PRACTICE INNOVATION: Expanding the role of the nuclear pharmacist in treating patients with NHL using radiolabeled monoclonal antibodies (MABs). INTERVENTIONS: The nuclear pharmacist provides specialized pharmaceutical care by being involved in planning patient care, administering diagnostic and therapeutic radiopharmaceuticals, performing individualized patient dose calculations, monitoring patients, and counseling patients. MAIN OUTCOME MEASURES: Number of patients treated with radiolabeled MABs. RESULTS: Since January 1996, 85 patients with NHL have been treated using 131I-tositumomab (Corixa, GlaxoSmithKline), an anti-B1 MAB, under various clinical research protocols requiring specialized pharmaceutical care. The nuclear pharmacist on the team provided direct patient care, assisting with the administration of diagnostic and therapeutic radiopharmaceuticals under a collaborative agreement with a nuclear medicine physician or a radiation oncologist. Other pharmaceutical care activities performed include calculating individual patient doses, obtaining medication histories, counseling patients on their therapy and on radiation safety after early release, and monitoring patients for adverse effects during medication infusion. Patients have responded favorably to nontraditional nuclear pharmacy activities. CONCLUSION: The nuclear pharmacist has become an important member of the health care team that provides a new and unique therapy for patients with NHL. To date, the nuclear pharmacist, in collaboration with the nuclear medicine physician or the radiation oncologist, has successfully administered the tositumomab and 131I-tositumomab combination therapy without significant incident.