An Evaluation of Some Common Laboratory Materials by Xray Attenuation, for use as Human Tissue Substitutes

Abstract

To develop readily available laboratory materials for probable
use as imaging phantoms or test objects, Laboratory Magnesium
Sulphate (MgSO4) and Table salt (NaCl) were used in the ratio
80:20% by weight with paraffin wax to form test materials
(MgSO4:PW1) and (NaCl:PW2). Rice powder, gelatine
separately, and a combination of gelatine (20g in 100ml of warm
water) and 100g rice powder were also made into test objects.
The ratios used were confirmed by matching different
constituents by weight of the test samples with the web based
photon interaction software XCOM designed by the National
Institute of Science and Technology, USA, to obtain close
matching with tissue data. Each test object was made into 1 cm
blocks for exposure to narrow beam x-rays over the diagnostic
energy range (50 – 150kV) under automatic exposure conditions.
Good agreement within 10%, was found between the measured
and calculated values for four of the five tested samples.
Matching of the tested materials with mass attenuation
coefficients of simulated tissue showed acceptable match at high
photon energies of 0.04 – 0,05 MeV and above for gelatine, PW1
(paraffin wax + MgSO4.6H2O) and Rigel (Rice + gelatine). These
materials can therefore be used as tissue substitutes in image
quality studies.