Effective Doses Associated with the Usual Multimodal Examinations in Nuclear Medicine

Objective

To know the effective doses (E) that can be given in the common multimodal procedures in nuclear medicine, single photon emission tomography and positron emission tomography, combined with computed tomography, SPECT/CT and PET/CT. Effective dose will be expressed according to background equivalent radiation time (BERT) and the contribution of the CT scan to the total dose will also be studied.

Material and methods

The effective dose of each procedure has been calculated as the sum of the external radiation dose (CT part) and the internal one (radiopharmaceutical administration). Data from each side were collected through extensive literature search.

Results

A range of minimum and maximum effective doses [E_min, E_max] associated with each procedure is shown. These doses range from 0.5 to 49.1 mSv. BERT ranges from 2.6 months to 20.4 years. The CT contribution to the total effective dose varies from 2.1% to 93%, according to the image acquisition protocol and its purpose. Performing a diagnostic CT scan increases the dose up to a factor of 4.3 times compared to the dose used for CT acquisition for attenuation correction and anatomic localization.

Conclusions

This article focuses on the effective dose level that can be given in multimodal procedures, bearing in mind that the data are subject to constant changes and should be updated periodically. It is important to know the dosimetric impact when the CT scan is added. The application of optimized protocols according to the indication of the study reduces patient's exposure without loss of significant information.