SU-F-I-56: High-Precision Gamma-Ray Analysis of Medical Isotopes

Journal Article · Wed Jun 15 00:00:00 EDT 2016 · Medical Physics

DOI:https://doi.org/10.1118/1.4955884· OSTI ID:22632121

Chopra, N; Chillery, T; Chowdhury, P; Lister, C ^[1]; McCutchan, E ^[2]; Smith, C ^[3]

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1. University of Massachusetts-Lowell, Lowell, MA (United States)
2. National Nuclear Data Center, Brookhaven National Laboratory, Upton, NY (United States)
3. BLIP Facility, Brookhaven National Laboratory, Upton, NY (United States)

Purpose: Advanced, time-resolved, Compton-suppressed gamma-ray spectroscopy with germanium detectors is implemented for assaying medical isotopes to study the radioactive decay process leading to a more accurate appraisal of the received dose and treatment planning. Lowell’s Array for Radiological Assay (LARA), a detector array that is comprised of six Compton-suppressed high-purity germanium detectors, is currently under development at UMass-Lowell which combines Compton-suppression and time-and-angle correlations to allow for highly efficient and highly sensitive measurements. Methods: Two isotopes produced Brookhaven Linac Isotope Producer (BLIP) were investigated. {sup 82}Sr which is the parent isotope for producing {sup 82}Rb is often used in cardiac PET. {sup 82}Sr gamma-ray spectrum is dominated by the 511keV photons from positron annihilation which prevent precise measurement of co-produced contaminant isotopes. A second project was to investigate the production of platinum isotopes. Natural platinum was bombarded with protons from 53MeV to 200MeV. The resulting spectrum was complicated due to the large number of stable platinum isotopes in the target, the variety of open reaction channels (p,xn), (p,pxn), (p,axn). Results: By using face-to-face NaI(Tl) counters 90-degrees to the Compton-suppressed germaniums to detect the 511keV photons, a much cleaner and more sensitive measurement of {sup 85}Sr and other contaminants was obtained. For the platinum target, we identified the production of {sup 188–189–191–195}Pt, {sup 191–192–193–194–195–196}Au and {sup 186–188–189–190–192–194–189–190–192–194}Ir. For example, at the lower energies (53 and 65MeV), we measured {sup 191}Pt production cross-sections of 144mb and 157mb. Considerable care was needed in following the process of dissolving and diluting the samples to get consistent results. The new LARA array will help us better ascertain the absolute efficiency of the counting system and more reliable production cross-sections. Conclusion: Modern HPGe spectroscopic techniques provide enhanced sensitivity, promising precise quantification of the quality of radioisotopes used in medical physics. Using new decay information may have non-trivial impact on treatment planning and dose-assessment.

• OSTI ID: 22632121
• Journal Information: Medical Physics, Vol. 43, Issue 6; Other Information: (c) 2016 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPES AND RADIATION SOURCES
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
62 RADIOLOGY AND NUCLEAR MEDICINE
ACCURACY
ANNIHILATION
CROSS SECTIONS
GAMMA RADIATION
GAMMA SPECTRA
GAMMA SPECTROSCOPY
GE SEMICONDUCTOR DETECTORS
GOLD 196
IRIDIUM 194
LINEAR ACCELERATORS
NUCLEAR DECAY
NUCLEAR MEDICINE
PLATINUM 191
PLATINUM 195
POSITRON COMPUTED TOMOGRAPHY
RADIATION DOSES
RUBIDIUM 82
STRONTIUM 82
STRONTIUM 85
TIME RESOLUTION