Spatial Characterization of Tray-Dependent Beam Structure and Exploratory Corner Geometry in a Preclinical Irradiator
Year: 2026
Type: preprint
Abstract: Spatial characterization of cabinet irradiators supports reproducible irradiation of biological specimens. We evaluated central and peripheral field characteristics of an X-RAD 320 at upper and lower tray positions. Ionization-chamber measurements across two-dimensional grids assessed dose profiles, surfaces, isodose distributions, flatness, symmetry, and centering. One EBT-XD radiochromic film was separately irradiated at each of four corner positions. Horizontal, vertical, and diagonal gray value profiles were fitted with Gompertz functions to locate the 80%, 50%, and 20% normalized response positions and assess transition width and apparent corner geometry. Our results showed that the upper tray produced a higher, more compact central dose region, whereas the lower tray produced a lower, broader field, with approximate plateau dimensions of 20 × 20 cm and 30 × 30 cm, respectively. Flatness and symmetry changed little across the inner 20–60% evaluation windows but rose markedly in the 80% and 100% windows as field boundaries were incorporated. Field-center displacement occurred predominantly along the negative Y-axis, with upper- and lower-tray offsets of − 3.76 and − 3.17 cm. X-direction offsets were comparable to the uncorrected 0.65-cm separation between chamber alignment and reference points and total offsets were approximately 3.8 and 3.3 cm. Film transition widths ranged from 2.13 to 7.41 mm and were generally wider at the lower tray. Exploratory ratios suggested square-leaning upper corners and arc-leaning lower corners. Central profiles alone did not fully characterize the fields and tray position and specimen placement should therefore be considered, particularly near field boundaries.
Source: Research Square
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7225646718