Thyroid doses and risk to paediatric patients undergoing neck CT examinations

Spampinato, Maria Vittoria; Tipnis, Sameer; Tavernier, Joshua; Huda, Walter

doi:10.1007/s00330-015-3590-x

Cited by 9 publications

(9 citation statements)

References 23 publications

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“…CT scans of children can result in thyroid radiation doses of 0.010 Gy for head CTs (38, 43), 0.027 Gy for chest CTs (43–45), 0.050 Gy for neck CTs (46, 47), 0.036 Gy for cervical spine CTs (48), and 0.008 Gy for abdominal CTs (43). With CT scans often repeated, multidetector row CT scans reducing scan times and enabling increased use of CT scans in pediatric medicine and the use of multiphase (repeat scanning before and after contrast injection) CT examinations, there is a high potential for pediatric patients to receive thyroid doses for which there is a demonstrably increased risk of thyroid cancer.…”

Section: Discussionmentioning

confidence: 99%

Thyroid Cancer Following Childhood Low-Dose Radiation Exposure: A Pooled Analysis of Nine Cohorts

Lubin

Adams

Shore

et al. 2017

The Journal of Clinical Endocrinology &Amp; Metabolism

131

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Context:The increased use of diagnostic and therapeutic procedures that involve radiation raises concerns about radiation effects, particularly in children and the radiosensitive thyroid gland.Objectives:Evaluation of relative risk (RR) trends for thyroid radiation doses <0.2 gray (Gy); evidence of a threshold dose; and possible modifiers of the dose-response, e.g., sex, age at exposure, time since exposure.Design and Setting:Pooled data from nine cohort studies of childhood external radiation exposure and thyroid cancer with individualized dose estimates, ≥1000 irradiated subjects or ≥10 thyroid cancer cases, with data limited to individuals receiving doses <0.2 Gy.Participants:Cohorts included the following: childhood cancer survivors (n = 2); children treated for benign diseases (n = 6); and children who survived the atomic bombings in Japan (n = 1). There were 252 cases and 2,588,559 person-years in irradiated individuals and 142 cases and 1,865,957 person-years in nonirradiated individuals.Intervention:There were no interventions.Main Outcome Measure:Incident thyroid cancers.Results:For both <0.2 and <0.1 Gy, RRs increased with thyroid dose (P < 0.01), without significant departure from linearity (P = 0.77 and P = 0.66, respectively). Estimates of threshold dose ranged from 0.0 to 0.03 Gy, with an upper 95% confidence bound of 0.04 Gy. The increasing dose–response trend persisted >45 years after exposure, was greater at younger age at exposure and younger attained age, and was similar by sex and number of treatments.Conclusions:Our analyses reaffirmed linearity of the dose response as the most plausible relationship for “as low as reasonably achievable” assessments for pediatric low-dose radiation-associated thyroid cancer risk.

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Section: Discussionmentioning

confidence: 99%

Thyroid Cancer Following Childhood Low-Dose Radiation Exposure: A Pooled Analysis of Nine Cohorts

Lubin

Adams

Shore

et al. 2017

The Journal of Clinical Endocrinology &Amp; Metabolism

131

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“…[1][2][3][4][5] Because of the smaller size of the patients and higher radiation sensitivity, pediatric CT poses some unique challenges in terms of achieving diagnostic-quality images with the least possible radiation burden to the patients. 4,[6][7][8][9][10][11][12] Optimization of a pediatric neck CT protocol is of utmost importance because in this study, the thyroid gland, one of the most radiosensitive organs, is directly exposed to the x-ray beam. [13][14][15] Thus, it is critical that the examination be clinically indicated, with a high benefit-to-risk ratio.…”

mentioning

confidence: 99%

Radiation Dose and Image Quality in Pediatric Neck CT

Tipnis¹,

Rieter²,

Patel³

et al. 2019

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: Optimization of pediatric neck CT protocols is of critical importance in order to maintain good diagnostic image quality while reducing the radiation burden. Our aim was to evaluate the image quality of pediatric neck CT studies before and after the implementation of a low radiation dose protocol. MATERIALS AND METHODS: We retrospectively reviewed 179 pediatric neck CT studies, 75 before and 104 after the implementation of low-dose protocols, performed in children 0-16 years of age. The 2 cohorts were divided into 3 age groups, 0-4, 5-9, and 10-16 years. The signal-to-noise ratio was calculated using the axial image through the true vocal folds. Three neuroradiologists assessed the image quality of the same CT scan using a 5-point scoring system. We compared the CT dose index volume, dose-length product, image-quality ratings, and SNR of studies conducted at baseline and with low-dose protocols. RESULTS: Image-quality ratings were lower in the low-dose than in the baseline cohort in children 10-16 years of age, but not in children 0-4 and 5-9 years of age. The SNR was lower in the low-dose cohort than in the baseline cohort in children 0-4 and 10-16 years of age, but not in children 5-9 years of age. Despite the decrease in image-quality scores in older children, 97% of the studies (73/75) in the baseline cohort and 96% of studies (100/104) in the low-dose cohort were considered of sufficient image quality. CONCLUSIONS: Images acquired with the low-dose CT protocols were deemed to be of sufficient quality for making a clinical diagnosis. Our initial results suggest that there may be an opportunity for further radiation dose reduction without compromising diagnostic image quality using iterative reconstruction algorithms.

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“…Thyroid absorbed doses from medical diagnostics are generally lower by 3-4 orders of magnitude than those administered by EBRT or RAI. Typical CT scans of the head and neck region may expose the thyroid to doses of up to 10-20 mGy in adults (Sinnott et al 2010, Su et al 2014 and up to 30-50 mGy in children (Spampinato et al 2015). Use of contrast agents containing iodine may increase thyroid doses in both paediatric and adult patients, but not by more than 35% (Dawson and Punwani 2009).…”

Section: Medical Diagnosticsmentioning

confidence: 99%

High-dose radiation exposure and hypothyroidism: aetiology, prevention and replacement therapy

2021

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Without any doubt, high dose radiation exposure can induce hypothyroidism. However, there are open questions related to the mechanisms of its induction, corresponding dose thresholds and possible countermeasures. Therefore, this review addresses the aetiology, prevention and therapy of radiation induced hypothyroidism. External beam radiotherapy with several 10 Gy to the head and neck region and radioiodine therapy with several 100 Gy thyroid absorbed dose can destroy the thyroid gland and can induce autoantibodies against thyroid tissue. According to recent literature, clinical hypothyroidism is observed at threshold doses of ∼10 Gy after external beam radiotherapy and of ∼50 Gy after radioiodine therapy, children being more sensitive than adults. In children and adolescents exposed by the Chernobyl accident with mean thyroid absorbed doses of 500–800 mGy, subclinical hypothyroidism has been detected in 3%–6% of the cases with significant correlation to thyroid absorbed doses above 2.5 Gy. In case of nuclear emergencies, iodine thyroid blocking (ITB) is the method of choice to keep thyroid absorbed doses low. Large doses of stable iodine affect two different steps of internalization of radioiodine (transport and organification); perchlorate affecting the transport only may be an alternative to iodine. Administered before radioiodine incorporation, the effect of 100 mg iodide or more is still about 90% after 1 days, 80% after 2 days, and 50% or less after 3 days. If administered (too) late after exposure to radioiodine, the theoretically expected protective effect of ITB is about 50% after 6 h, 25% after 12 h, and about 6% after 24 h. In case of repeated or continuous exposure, repeated administration of 50 mg of iodide daily is indicated. If radiation-induced hypothyroidism cannot be avoided, thyroid hormone replacement therapy with individualized dosing and regular monitoring in order to maintain thyroid-stimulating hormone levels within the normal range ensures normal life expectancy.

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Thyroid doses and risk to paediatric patients undergoing neck CT examinations

Cited by 9 publications

References 23 publications

Thyroid Cancer Following Childhood Low-Dose Radiation Exposure: A Pooled Analysis of Nine Cohorts

Thyroid Cancer Following Childhood Low-Dose Radiation Exposure: A Pooled Analysis of Nine Cohorts

Radiation Dose and Image Quality in Pediatric Neck CT

High-dose radiation exposure and hypothyroidism: aetiology, prevention and replacement therapy

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