Quantitative uptake measurements of I-131 (364 keV) within the tomographic plane of a specially collimated SPECT system

Conference · Sun Jan 01 04:00:00 EST 1984 · J. Nucl. Med.; (United States)

OSTI ID:6843570

Clarke, L P; Saw, C B; Leong, L K; Serafini, A N

The use of SPECT for uptake measurements requires a linear relationship between the measured counts within a tomographic plane and its activity distribution. Many factors influence this relationship, and these include filter type and attenuation correction methods. However, for higher photon energy (I-131, 364 keV), photon penetration through the collimator or detector shielding may degrade, for example, the tomographic plane and slice thickness resolution and the ability to differentiate activity within a slice and between slices. A SPECT system (Picker International Dyna Camera), equipped with a specialized (low sensitivity) thick septa collimator for I-131 (364 keV) and 511 keV detector shielding is proposed for quantitative measurements. The influence of photon penetration was significantly reduced, with transverse plane and slice thickness resolution of 18 mm FWHM and 37 mm FWIM for a radius of rotation of 14 cm. Iodine collimators typically have FWTM 5-10 times the FWHM. A Jaszczak phantom was imaged with I-131, with two bar quadrants observed with diameters of 16 and 12.7 mm. The SPECT resolution data was equal to a low energy general purpose collimator. A multi-concentric ring (contrast) phantom was designed to quantitatively evaluate the SPECT system. A linear relationship was observed between the measured counts for a transverse plane and I-131 activity within the rings. Data suggest that with appropriate collimation and detector shielding SPECT systems may be used for quantitative measurements at higher photon energy.

• Research Organization: Univ. of Miami, Miami, FL
• OSTI ID: 6843570
• Report Number(s): CONF-840619-
• Conference Information: Journal Name: J. Nucl. Med.; (United States) Journal Volume: 25:5
• Country of Publication: United States
• Language: English

Related Subjects

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61 RADIATION PROTECTION AND DOSIMETRY
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655003 -- Medical Physics-- Dosimetry
ATTENUATION
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
COLLIMATORS
COMPUTERIZED TOMOGRAPHY
DAYS LIVING RADIOISOTOPES
DIAGNOSTIC TECHNIQUES
DIMENSIONS
ELEMENTARY PARTICLES
EMISSION COMPUTED TOMOGRAPHY
ENERGY RANGE
FILTERS
INTERMEDIATE MASS NUCLEI
IODINE 131
IODINE ISOTOPES
ISOTOPES
KEV RANGE
KEV RANGE 100-1000
MASSLESS PARTICLES
MOCKUP
MOTION
NUCLEI
ODD-EVEN NUCLEI
OPTICAL FILTERS
PHANTOMS
PHOTONS
RADIOISOTOPES
RESOLUTION
ROTATION
SENSITIVITY
SHIELDING
SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY
STRUCTURAL MODELS
THICKNESS
TOMOGRAPHY
UPTAKE