Evaluation of agreement between two instruments in measurements of radiation dose rates in cats that underwent iodine I 131 treatment.
OBJECTIVE
To assess agreement between a commercially available Geiger-Meuller (GM) survey meter and millirem tissue-equivalent (TE) meter for measuring radioactivity in cats treated with sodium iodine I 131 ((131)I).


METHODS
15 cats with hyperthyroidism and undergoing (131)I treatment.


METHODS
Duplicate measurements were obtained at a distance of 30 cm from the thyroid region of each cat's neck by 2 observers who used both meters on day 3 or 5 after(131)I administration. Comparisons of measurements between meters and observers were made, with limits of agreement defined as the mean difference +/- 2 SDs of the differences.


RESULTS
For observer 1, the mean of the differences in the 2 meters' measurements in all cats was 0.012 mSv/h (SD, 0.011 mSv/h). For observer 2, the mean of the differences in measurements was 0.012 mSv/h (SD, 0.010 mSv/h). For the GM meter, the mean of the differences of the 2 observers for all cats was 0.003 mSv/h (SD, 0.011 mSv/h). For the TE meter, the mean of the differences of the 2 observers for all cats was 0.003 mSv/h (SD, 0.007 mSv/h).


CONCLUSIONS
Results indicate that there was considerable agreement between meters and observers in measurements of radioactivity in cats treated with (131)I. Measurements obtained by use of the GM meter may be approximately 0.01 mSv/h less than or 0.03 mSv/h higher than those obtained with the TE meter. If this range is acceptable for an institution's release criteria, the 2 meters should be considered interchangeable and acceptable for clinical use.
Chalmers
Heather J
HJ
Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Scrivani
Peter V
PV
Dykes
Nathan L
NL
Hubble
Lorna J
LJ
Hobbs
Jeff M
JM
Erb
Hollis N
HN
D000818:Animals; D002415:Cats; D007457:Iodine Radioisotopes / Q000032:analysis*; D015588:Observer Variation; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000592:standards*; D011874:Radiometry / Q000592:standards / Q000662:veterinary; D011878:Radiotherapy / Q000662:veterinary*; D011879:Radiotherapy Dosage / Q000662:veterinary; D015203:Reproducibility of Results
D007457:Iodine Radioisotopes