Radiation dose reduction through combining positron emission tomography/computed tomography (PET/CT) and diagnostic CT in children and young adults with lymphoma
Both [F-18]2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (18F–FDG PET/CT) and diagnostic CT are at times required for lymphoma staging. This means some body segments are exposed twice to X-rays for generation of CT data (diagnostic CT + localization CT).
To describe a combined PET/diagnostic CT approach that modulates CT tube current along the z-axis, providing diagnostic CT of some body segments and localization CT of the remaining body segments, thereby reducing patient radiation dose.
Materials and methods
We retrospectively compared total patient radiation dose between combined PET/diagnostic CT and separately acquired PET/CT and diagnostic CT exams. When available, we calculated effective doses for both approaches in the same patient; otherwise, we used data from patients of similar size. To confirm image quality, we compared image noise (Hounsfield unit [HU] standard deviation) as measured in the liver on both combined and separately acquired diagnostic CT images. We used t-tests for dose comparisons and two one-sided tests for image-quality equivalence testing.
Mean total effective dose for the CT component of the combined and separately acquired diagnostic CT exams were 6.20±2.69 and 8.17±2.61 mSv, respectively (P<0.0001). Average dose savings with the combined approach was 24.8±17.8% (2.60±2.51 mSv [range: 0.32–4.72 mSv]) of total CT effective dose. Image noise was not statistically significantly different between approaches (12.2±1.8 HU vs. 11.7±1.5 HU for the combined and separately acquired diagnostic CT images, respectively).
A combined PET/diagnostic CT approach as described offers dose savings at similar image quality for children and young adults with lymphoma who have indications for both PET and diagnostic CT examinations.
KeywordsAdolescents Children Dose reduction Computed tomography Lymphoma Positron emission tomography Staging Young adults
Compliance with ethical standards
Conflicts of interest
A.T. Trout receives royalties from Elsevier for a nuclear medicine text. Z. Qi, E.L. Gates and M.M. O’Brien have no conflicts of interest to report.
- 7.Pinilla I, Gomez-Leon N, Del Campo-Del Val L et al (2011) Diagnostic value of CT, PET and combined PET/CT performed with low-dose unenhanced CT and full-dose enhanced CT in the initial staging of lymphoma. Q J Nucl Med Mol Imaging 55:567–575Google Scholar
- 9.Alessio AM, Kinahan PE (2017) CT protocol selection in PET-CT imaging. Image Wisely. http://www.imagewisely.org/imaging-modalities/nuclear-medicine/articles/ct-protocol-selection. Accessed 23 Aug 2017
- 12.McCollough C, Cody D, Edyvean S et al (2008) The measurement, reporting, and management of radiation dose in CT: report of AAPM task group 23. American Association of Physicists in Medicine, AlexandriaGoogle Scholar
- 17.Simpson WL Jr, Lee KM, Sosa N et al (2016) Lymph nodes can accurately be measured on PET-CT for lymphoma staging/restaging without a concomitant contrast enhanced CT scan. Leuk Lymphoma 57:1083–1093Google Scholar