Strategies to Improve CT Dose Optimization for Hybrid PET/CT Imaging

Abstract

Background: To evaluate whether current dose reduction strategies for the CT component of hybrid Positron Emission Tomography-Computed Tomography (PET/CT) systems could reduce patient dose with maintaining adequate image quality for PET/CT studies. Materials and Methods: Literature survey was initially based on the selection of keywords and years of publication to identify potentially relevant articles, then the further search was conducted on the authors and references from these articles. The abstract of each article was first appraised to decide whether the content was relevant to this research question. The articles were classified into five groups: studies on dosimetry, studies on radiation-induced diseases, studies on dose reduction methods for CT-based attenuation correction (CTAC), studies on dose reduction methods for CT localization, and studies on reducing the need for a full-dose diagnostic CT in PET/CT imaging. 58 peer-reviewed articles were selected and appraised and 29 articles were used to compose this literature review. Results: The published nuclear medicine and medical physics literature were reviewed. CT dose contributed 47% -81% of the total effective dose of a standard PET/CT study and was associated with radiation-induced diseases. The dose reduction techniques were extracted and divided into three categories: reducing the CT dose for attenuation correction (AC) and localization, selectively localizing CT use, and reducing the need for a full-dose diagnostic CT. Conclusion: Three strategies have been demonstrated, with high potential for reducing patient dose while maintaining an adequate CT image quality, used for CTCA localization and diagnosis, respectively.

The Role of PET-CT-Guided Metabolic Biopsies in Improving Yield of Inconclusive Anatomical Biopsies: A Review of 5 Years in a Teaching Hospital

“…Recently, researchers studied the utility of low- and ultra-low-dose CT protocols and demonstrated that significant reduction in radiation dose can be achieved with no detrimental influence on the diagnostic rates of the biopsy operations. Incorporating these novel CT techniques and decreasing the amount of 18F-FDG provided the bare minimum and is, thus, a partial solution to the problem of increased radiation exposure to patients [ 22 ]. In our investigation, the average radiation exposure per procedure for operating personnel was 0.014 mSv, which is far below the permitted annual limits.…”

Ultra‐low dose CT scanning for PET/CT

“…PET/CT is an invaluable tool for providing quantitative measures related to diagnosis, therapy response evaluation, and prediction of numerous health conditions. The widespread application of this imaging technique is a product of its high sensitivity, specificity, and diagnostic accuracy related to the molecular processes in vivo 1,2 …”

“…In patients with non‐oncological diseases, the total amount of radiation dose, especially for younger patients or even healthy volunteers poses a stumbling block for using PET, limiting its potentially valuable role. Even more so, the radiation dose is of particular concern in scanning children as they are more sensitive to radiation and have a longer post‐irradiation life expectancy 2 . Furthermore, in various conditions, patients may benefit tremendously by receiving multiple CT and PET/CT scans frequently for monitoring treatment, thereby mostly covering the whole‐body 9,10 .…”

“…The widespread application of this imaging technique is a product of its high sensitivity, specificity, and diagnostic accuracy related to the molecular processes in vivo. 1,2 With a PET/CT system, the CT component can be used for any of the three purposes: (1) attenuation correction (AC) of the PET emission data, which only requires an elementary delineation of tissues to estimate photon attenuation (µ-map) within the patient, and which is essential for quantitative PET imaging, (2) anatomical localization, that is, imaging of morphological and anatomical features with sufficient spatial resolution, image quality and contrast to anatomically correlate the PET tracer uptake. (3) Diagnostics, which requires a fully diagnostic CT according to standard radiology guidelines.…”

“…Even more so, the radiation dose is of particular concern in scanning children as they are more sensitive to radiation and have a longer post-irradiation life expectancy. 2 Furthermore, in various conditions, patients may benefit tremendously by receiving multiple CT and PET/CT scans frequently for monitoring treatment, thereby mostly covering the whole-body. 9,10 Therefore, the globally adopted radiation protection framework follows the well-known ''As Low As Reasonably Achievableʺ (ALARA) principle to ensure a careful balance between the benefits and risks of using radiation in diagnostic imaging.…”