Evaluation of radiation dose to pediatric models from whole body PET/CT imaging

Abstract

Positron emission tomography (PET)/computed tomography (CT) is a well‐known modality for the diagnosis of various diseases in children and adult patients. On the other hand, younger patients are more radiosensitive than adults, so there are concerns about the level of ionizing radiation exposure in pediatric whole body PET/CT imaging. In this regard, comprehensive specific radiation dosimetry for whole body PET/CT imaging is highly desired for different ages, sizes, and shapes. Therefore, in this study, organ absorbed doses were evaluated for pediatric voxel models from 4 to 14 years old and compared with those of ICRP phantoms. Monte Carlo calculation was performed to evaluate S‐value, absorbed dose, and effective dose from 18F‐FDG radiotracers and whole body CT scan for different computational models, including 4‐ to 14‐year‐old phantoms. The results showed that the S‐value and, therefore, absorbed dose of 18F‐FDG strongly depended on the phantom anatomy. These variations were justified by the distance between source and target organs. Moreover, on average, the absorbed doses from whole body CT scans were 13.5 times lower than those from 18F‐FDG for all organs. According to the results, various anatomies and ages should be considered for accurate dose evaluation. These data can be used for specific risk assessment of the pediatric population in clinical nuclear imaging.

Comparison of the different imaging modalities used to image pediatric oncology patients: A COG diagnostic imaging committee/SPR oncology committee white paper

“…93 Mohammadi et al suggested that any modeling used to assess dose from these scintigraphic studies should ensure a variety of ages, and anatomies are used for accurate dose evaluation. 94 PET/MRI systems can further reduce the radiation exposure by utilizing MRI instead of CT for attenuation correction for the PET imaging. The MRI imaging will determine the length of the PET acquisition because it is usually longer than optimal PET acquisition per area of body imaged.…”

“…Mohammadi et al. suggested that any modeling used to assess dose from these scintigraphic studies should ensure a variety of ages, and anatomies are used for accurate dose evaluation 94 …”

Patient-specific radiation dose for Chinese pediatric patients undergoing whole-body PET/CT examinations

“…The calculation of radiation dose for pediatric patients undergoing PET studies requires sophisticated consideration of two main factors: patient modeling and radiopharmaceutical biodistribution. Many kinds of anthropomorphic phantoms with different age, sex and size have been established to model patients and their dosimetry properties (Khamwan et al 2018, Mohammadi and Akhlaghi 2022, Ferreira et al 2023. However, reference phantoms may cause considerable uncertainty in dose estimation due to the variation in whole-body properties among individuals (Neira et al 2020).…”

Optimized low-dose positron emission tomography/computed tomography schemes in pediatric tumor patients: a randomized clinical trial

“…Compared to adult CT, pediatric CT may significantly increase the estimated risk of death from cancer (18). The lifetime attributable risks of all cancer morbidity and mortality in 10-year-old children (males and females) were almost 5.29 and 3.16 times that of 70-year-old adults (men and women), and these risks were even greater for younger children (19). Thus, it is of clinical significance to reduce the radiation dose while ensuring the quality of PET/CT images in children.…”