Evaluation of the water equivalence of solid phantoms using gamma ray transmission measurements

Gamma ray transmission measurements have been used to evaluate the water equivalence of solid phantoms. Technetium-99m was used in narrow beam geometry and the transmission of photons measured, using a gamma camera, through varying thickness of the solid phantom material and water. Measured transmis...

Full description

Saved in:
Bibliographic Details
Published in:Radiation measurements 2008-08, Vol.43 (7), p.1258-1264
Main Authors: Hill, R.F., Brown, S., Baldock, C.
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
EGSnrc Monte Carlo
Exact sciences and technology
Geochronology
Isotope geochemistry. Geochronology
Low energy photons
Solid phantoms
Technetium-99m
Water equivalency
XCOM
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Gamma ray transmission measurements have been used to evaluate the water equivalence of solid phantoms. Technetium-99m was used in narrow beam geometry and the transmission of photons measured, using a gamma camera, through varying thickness of the solid phantom material and water. Measured transmission values were compared with Monte Carlo calculated transmission data using the EGSnrc Monte Carlo code to score fluence in a geometry similar to that of the measurements. The results indicate that the RMI457 Solid Water, CMNC Plastic Water and PTW RW3 solid phantoms had similar transmission values as compared to water to within ± 1.5 % . However, Perspex had a greater deviation in the transmission values up to ± 4 % . The agreement between the measured and EGSnrc calculated transmission values agreed to within ± 1 % over the range of phantom thickness studied. The linear attenuation coefficients at the gamma ray energy of 140.5 keV were determined from the measured and EGSnrc calculated transmission data and compared with predicted values derived from data provided by the National Institute of Standards and Technology (NIST) using the XCOM program. The coefficients derived from the measured data were up to 6% lower than those predicted by the XCOM program, while the coefficients determined from the Monte Carlo calculations were between measured and XCOM values. The results indicate that a similar process can be followed to determine the water equivalency of other solid phantoms and at other photon energies.
ISSN:1350-4487
1879-0925
DOI:10.1016/j.radmeas.2008.01.019