DEVELOPMENT OF HIGH THROUGHPUT RADIOLOGICAL BIOASSAYS SCREENING METHOD

Abstract

Immediately after a radiologist dispersion event or
nuclear disaster, a method is needed to quickly assay a
large number of people for internal contamination. While
no such method exists presently, we propose to adapt a
Nuclear Medicine Gamma Camera and use internal
dosimetric calculations to enable the high-throughput
screening of urine bioassay samples. We determined the
efficacy of using a nuclear medicine camera for high throughput
bioassay screening and determined the
minimum detectable concentrations (MDC) of
radioactive material F-18 (511 keV) and Tc-99m (140 keV) that can be detected with our methodology. For this
investigation, contribution from background radiation
was determined and statistically compared against our
signal to determine the MDC, the energy response of the
Gamma Camera determined, and the effect of sample
volume on detector efficiency determined. Our MDCs
next were compared against the Protective Action
Guidelines (PAGs) recommended by the Environmental
Protection Agency. After the MDCs for various isotopes
were calculated, the resulting radiation dose equivalent
(mSv) were calculated from these potential intakes. Plain
tap water was used to simulate human urine because of
their approximately identical physical densities, and Tc-
99m and F-18 were the radioactive isotopes tested. The
samples were imaged and counted with a Symbian Dual
Head SPECT/CT and a desktop computer installed with
E.SOFTVA25A; version 6.5.9.19 at Brigham and
Women’s Hospital. This technique demonstrated the
ability to measure 35 samples in 10 min (approximately
1,600 samples in 8 h), which makes it the fastest
technique available presently for large-scale screening
bioassay. Our results also demonstrate that this technique
will achieve MDCs 10% below the levels recommended
by the EPA PAGs.