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Positional impact on ocular lens and thyroid radiation doses during feline cranial CT: A thermoluminescent dosimetry
Kurtuluş Parlak1, Osman Vefa Gul2, Hilmican Ergin1
1Department of Surgery, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey.
Objectives:
The increasing use of CT in feline medicine necessitates the optimization of radiation protocols to adhere to the ALARA (as low as reasonably achievable) principle. This prospective study aimed to evaluate the impact of patient positioning (dorsoventral (DV) vs ventrodorsal (VD)) on radiation doses absorbed by the ocular lenses and thyroid gland during feline cranial CT.
Methods:
A total of 70 cats were divided into two equal groups (DV: n = 35, VD: n = 35). Radiation doses were measured using thermoluminescent dosimeters (TLD-100) placed at the anatomical projections of the target organs.
Results:
Although no statistically significant difference was observed in ocular lens doses between the groups (P >0.05), VD positioning resulted in a 24.4% reduction in mean radiation dose absorbed by the thyroid gland compared with the DV position (1.33 ± 0.17 mGy vs 1.76 ± 0.35 mGy, respectively; P = 4.97 ×10-9). This reduction is attributed to the "natural shielding" effect provided by the dorsal axial skeleton and epaxial muscles in the VD position.
Conclusions And Relevance:
VD positioning offers a significant dosimetric advantage for protecting the thyroid gland without requiring additional equipment or compromising diagnostic quality. Adopting the VD position as a routine standard in feline cranial CT is recommended to minimize radiation exposure to the thyroid gland.
