Study of Local Diagnostic Reference Levels (DRLs) and Evaluation of Patient Radiation Doses of SPECT/CT Parathyroid Scan at Suppasitthiprasong Hospital


  • Bulan Wapee Division of Nuclear Medicine, Department of Radiology, Sunprasitthiprasong Hospital, Ubonratchathani Province.


diagnostic reference levels, administered activity, volumetric computed tomography dose index, dose length product, diagnostic nuclear medicine


Background and Objectives: Parathyroid scintigraphy is the predominant nuclear medicine procedure used to identify abnormally hyperactive parathyroid tissue. Its utilization is increasing in various medical settings. This examination can be performed with precision to determine the function and location of the parathyroid minor lesion. Currently, Suppasitthiprasong Hospital does not have established local DRLs for parathyroid scans. Hence, the aim of this study was to conduct a survey and establish the local DRLs for the administered activity of parathyroid scans. Additionally, it aimed to assess the radiation dose received by patients from hybrid SPECT/CT scans and compare the obtained DRLs with the Thai national DRLs and those of other countries.

Methods: The retrospective descriptive study was conducted by collecting. parathyroid scan data included one hundred patients (44 females and 56 males) in 2022. The 75th percentiles of the administered activities and volumetric computed tomography dose index; CTDIvol, dose length product; DLP were obtained from the GE Discovery670 NM/CT Scanner (hybrid CT Optima 540 model). The effective dose (Deff) was then determined for each CT study.

Results: The DRLs for 99mTc-O-4 and 99mTc-MIBI were 159.1 MBq and 814 MBq, respectively. The radiation doses for volumetric computed tomography dose index, dose length product and Deff from the hybrid CT neck were 14.41 mGy, 577.42 mGy-cm, and 3.12 mSv, respectively.

Conclusion: The 99mTc-MIBI levels exceeded the Thai National DRLs, but remained below those of other countries. Hence, it is necessary to modify the local DRLs for activities of 99mTc-MIBI in future. The assessment of the radiation dose that patients receive from hybrid CT scans of the neck indicates that it is greater compared to the standards set by the Thai National and other nations. Consequently, it is necessary to review and adjust the parameters (kVp, mAs) of the hybrid CT neck protocol in order to reduce the radiation dose experienced by patients.


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How to Cite

Wapee B. Study of Local Diagnostic Reference Levels (DRLs) and Evaluation of Patient Radiation Doses of SPECT/CT Parathyroid Scan at Suppasitthiprasong Hospital . SRIMEDJ [Internet]. 2024 Apr. 24 [cited 2024 Jun. 19];39(2):184-90. Available from:



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