The RS 2400 irradiator has been looked to as a replacement for discontinued
gamma irradiators. The RS 2400 has a cylindrical, rather than point, x-ray source, which
yields higher dose rates. The irradiator unit allows the user to set the current, voltage,
and time for which the sample is to be irradiated, but gives no conversion between these
values and the dose delivered. Working with Mississippi State University’s
Experimental Seafood Processing Laboratory (ESPL), the purpose of this research was
to characterize the dose delivered by the RS 2400 for typical operating conditions.
The RS 2400 exposure rate increases, as expected, as the current and voltage are
increased. The x-ray beam is uniform within 10% at the surface of the x-ray tube over a
wide range of voltages, with the exception of the leftmost 5 cm of the tube, where
structural supports are located. At the maximum operating parameters (150 kV and 45
mA), the beam has a first half value layer (HVL1) of 13.66 mm aluminum, a
homogeneity coefficient of 0.47, and equivalent photon energy (hveq) of 88.5 keV. This
suggests a broad energy x-ray beam.
The maximum deliverable dose rate to tissue at the surface of the x-ray tube is 65
Gy min-1 ± 3.1%, but it is unlikely that any sample will ever be irradiated this close to the x-ray tube. The standard sample canisters are 7.62 cm in diameter and the maximum
deliverable dose rate to tissue at the canister location (with no canister present) is 37 Gy
min-1 ± 3.1%. This is similar to the 45 Gy min-1 value that Rad Source Technologies,
Inc. gives for the irradiator.
Irradiation of live oysters is of primary interest to the ESPL. For irradiation,
oysters will most likely be placed in the 10.2 cm diameter plastic canisters since the 7.62
cm diameter canisters are not wide enough to hold larger oysters. The oyster shells and
increased distance from the x-ray source reduce the maximum deliverable dose rate to
14.1 Gy min-1 ± 6.5% for thin-shelled oysters and 12.3 Gy min-1 ± 6.2% for thick-shelled
oysters.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2982 |
| Date | 15 May 2009 |
| Creators | Wagner, Jennifer Ann Koop |
| Contributors | Ford, John |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | electronic, application/pdf, born digital |
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