Planar gamma camera imaging and quantitation of Yttrium-90 bremsstrahlung

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Journal of Nuclear Medicine

OSTI ID:255210

Shen, S; DeNardo, G L; Yuan, A ^[1]

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1. Univ. of California at Davis, Sacramento, CA (United States); and others

Yttrium-90 is a promising radionuclide for radioimmunotherapy of cancer because of its energetic beta emissions. Therapeutic management requires quantitative imaging to assess the pharmacokinetics and radiation dosimetry of the {sup 90}Y-labeled antibody. Conventional gamma photon imaging methods cannot be easily applied to imaging of {sup 90}Y-bremsstrahlung because of its continuous energy spectrum. The sensitivity, resolution and source-to-background signal ratio (S/B) of the detector system for {sup 90}Y-bremsstrahlung were investigated for various collimators and energy windows in order to determine optimum conditions for quantitative imaging. After these conditions were determined, the accuracy of quantitation of {sup 90}Y activity in an Alderson abdominal phantom was examined. When the energy-window width was increased, the benefit of increased sensitivity outweighed degradation in resolution and S/B ratio until the manufacturer`s energy specifications for the collimator were exceeded. Using the same energy window, the authors improved resolution and S/B for the medium-energy (ME) collimator when compared to the low-energy, all-purpose (LEAP) collimator, and there was little additional improvement using the high-energy (HE) collimator. Camera sensitivity under tissue equivalent conditions was 4.2 times greater for the LEAP and 1.7 times greater for the ME collimators when compared to the HE collimator. Thus, the best, most practical selections were found to be the ME collimator and an energy window of 55-285 keV. When they used these optimal conditions for image acquisition, the estimation of {sup 90}Y activity in organs and tumors was within 15% of the true activities. The results for this study suggest that reasonable accuracy can be achieved in clinical radioimmunotherapy using {sup 90}Y-bremsstrahlung quantitation. 28 refs., 5 figs., 7 tabs.

• DOE Contract Number: FG03-84ER60233
• OSTI ID: 255210
• Journal Information: Journal of Nuclear Medicine, Journal Name: Journal of Nuclear Medicine Journal Issue: 8 Vol. 35; ISSN 0161-5505; ISSN JNMEAQ
• Country of Publication: United States
• Language: English

Related Subjects

56 BIOLOGY AND MEDICINE
APPLIED STUDIES
BREMSSTRAHLUNG
DOSIMETRY
NEOPLASMS
RADIATION DOSES
RADIOIMMUNOTHERAPY
RADIOTHERAPY
YTTRIUM 90