Scintillators for positron emission tomography

Conference · Fri Sep 01 04:00:00 EDT 1995

OSTI ID:132773

Moses, W W; Derenzo, S E

Like most applications that utilize scintillators for gamma detection, Positron Emission Tomography (PET) desires materials with high light output, short decay time, and excellent stopping power that are also inexpensive, mechanically rugged, and chemically inert. Realizing that this ``ultimate`` scintillator may not exist, this paper evaluates the relative importance of these qualities and describes their impact on the imaging performance of PET. The most important PET scintillator quality is the ability to absorb 511 keV photons in a small volume, which affects the spatial resolution of the camera. The dominant factor is a short attenuation length ({le} 1.5 cm is required), although a high photoelectric fraction is also important (> 30% is desired). The next most important quality is a short decay time, which affects both the dead time and the coincidence timing resolution. Detection rates for single 511 keV photons can be extremely high, so decay times {le} 500 ns are essential to avoid dead time losses. In addition, positron annihilations are identified by time coincidence so {le}5 ns fwhm coincidence pair timing resolution is required to identify events with narrow coincidence windows, reducing contamination due to accidental coincidences. Current trends in PET cameras are toward septaless, ``fully-3D`` cameras, which have significantly higher count rates than conventional 2-D cameras and so place higher demands on scintillator decay time. Light output affects energy resolution, and thus the ability of the camera to identify and reject events where the initial 511 keV photon has undergone Compton scatter in the patient. The scatter to true event fraction is much higher in fully-3D cameras than in 2-D cameras, so future PET cameras would benefit from scintillators with a 511 keV energy resolution < 10--12% fwhm.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States); Department of Health and Human Services, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 132773
• Report Number(s): LBL--37720; CONF-9508187--2; ON: DE96002440; CNN: Grant R01 CA48002; Grant P01 HL25840; Grant R01 NS29655
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
55 BIOLOGY AND MEDICINE
BASIC STUDIES
EMISSION SPECTRA
GAMMA DETECTION
MATERIALS
PHOSPHORS
PHOTOMULTIPLIERS
POSITRON CAMERAS
POSITRON COMPUTED TOMOGRAPHY
SOLID SCINTILLATION DETECTORS