Radiation dose from¹⁸F-FDG PET/CT procedures: influence of specific CT model and protocols

Abstract

The increasing use of the integrated 18F-fluoro-deoxy-glucose (FDG) positron emission tomography/computed tomography (PET/CT) imaging modality in the management of tubercular lesions raises concerns about associated radiation exposure. This work aimed to study the effects of CT model and study protocols on the overall radiation dose from a PET/CT examination. Two PET/CT systems with five representative CT exposure protocols applied for clinical patients in PET/CT imaging following retrospective evaluation were studied. CT doses were calculated using the CT-Expo dosimetry software (version 2.4), while the PET component dose was estimated applying the International Commission on Radiological Protection (ICRP) 106 dose coefficients. The total effective dose ranged from 8.0 to 24.05 mSv for system I and 8.35 to 26.85 mSv for system II, resulting in differences of 4.3 to 15% for the low-dose scan and 4.1 to 11% for standard dose scans. The CT component contribution to the total dose was between 32 and 77% for system I, and 35 and 79% for system II. However, the contributions were not significantly different (p > 0.05) for all protocols. The observed variation in CT contribution represents a requisite pedestal on the need for a nation-wide dose assessment for further optimization of the imaging procedure to maximize benefit to patients.

Embryo/Fetus Doses from 18F-Fludeoxyglucose Radiopharmaceutical in Positron Emission Tomography/ Computed Tomography

“…The CT component contribution to the total dose was between 32% and 77% for GE, and 35% and 79% for Philips. [ 16 ] Huang et al . [ 17 ] reported that the fetal dose from 328 MBq 18 F-FDG was 6.25 mSv, and Liu et al .…”

EANM procedural recommendations for managing the paediatric patient in diagnostic nuclear medicine

“…Chawla et al [ 74 ] reported in their study that, from 2002 to 2007, effective doses due to PET/CT ranged from 2.7 to 54.2 milliSieverts (mSv) for the CT scanning and from 0.4 to 7.7 mSv for the PET procedure [ 75 ]. Some authors [ 76 – 79 ] reported that a non-optimized CT scan can contribute up to 80% of the whole radiation burden in paediatric NM exams. In this context, the Image Gently ’s slogan seems more important than ever: “ One size does not fit all ” [ 80 ].…”

“…The optimization of CT in hybrid imaging is mainly based on adjusting acquisition parameters [ 82 – 88 ] as well as reconstruction algorithms [ 89 , 90 ]. Imaging tests and subsequent standardization of the most common protocols used in the department can help reduce patient exposure [ 76 , 91 ] and quantify any bias that may be introduced using a very low dose CT for attenuation correction [ 92 , 93 ].…”

Ultra‐low dose CT scanning for PET/CT

“…Advanced image reconstruction methods 13–15 and improved detectors have contributed to PET/CT images of much higher spatial resolution and signal‐to‐noise ratio even at substantially lower injected radiotracer dosages. In addition, new CT hardware and software has been proposed to minimize radiation exposure due to the CT component 1,16–18 …”

“…In addition, new CT hardware and software has been proposed to minimize radiation exposure due to the CT component. 1,[16][17][18] Previous studies reported that CT contributes to over 50% of the estimated average radiation exposure in 18 F-fluorodeoxyglucose ([ 18 F]FDG) PET/CT examinations-depending on the application. 16,17,19 In South Korea, a nationwide survey was conducted involving all institutions operating PET/CT scanners to evaluate the patient's effective dose for different diagnostic PET/CT procedures performed with various PET tracers.…”