Diagnostic radiation exposure in children with spinal dysraphism: an estimation of the cumulative effective dose in a cohort of 135 children from The Netherlands

Radiation exposure in pediatric videourodynamics: An evaluation of safety in comparison to voiding cystourethrogram

INTRODUCTION

Children with spina bifida (SB) undergo a videourodynamic study (VUDS) or urodynamic study and voiding cystourethrogram (VCUG). A standardized protocol for imaging during a pediatric VUDS has not been established. Our aim is to quantify radiation exposure and establish a baseline for children with spina bifida (SB) undergoing VUDS in current practice at our institution.

METHODS

This is a retrospective study from 2013 to 2020 of consecutive pediatric SB patients undergoing VUDS by a single provider. Patients were categorized into three groups based on age; group 1 (0-2 YR), group 2 (2-10 YR), group 3 (>10 YR). Radiation data was reported as mean air kerma (AK), dose area product (DAP) and exposure time (seconds). Effective dose (ED) was calculated based on radiation quantity (Air Kerma, AK) and organ sensitivity. The lifetime attributable risk (LAR) was calculated based on AK and a risk coefficient. Data points calculated for patients undergoing VUDS were then compared to age matched institutional VCUG data in the same age groups.

RESULTS

398 patients undergoing VUDS met inclusion criteria and 262 independent patients underwent VCUG. ED increased with age in both VUDS and VCUG. All VCUG groups were found to have a higher ED than VUDS. The LAR for VUDS groups 1-3 was 0.001, 0.002, and 0.006, respectively. Reported in percentages, there is a 0.1%, 0.2%, and 0.6% chance, respectively, of age groups 1, 2 and 3 developing cancer as a result of the radiation exposure from a VUDS.

DISCUSSION

Our study found that ED was low across all age groups for VUDS, comparing favorably to the VCUG groups. VCUG was selected as a benchmark comparison for its diagnostic similarities and, at times, overlapping indications. Few studies have described ED with respect to VUDS or extrapolate the ED of VUDS into LAR in the pediatric population. We recognize that we have not determined the true ED of the gonads and bladder, rather we have overestimated, as the data is based on an international reference point proximal to the exposed individual. However, LAR was calculated for each age group and revealed that patients are at a negligible increased risk of developing malignancy secondary to exposure compared to the general population.

CONCLUSION

Our current practice for pediatric VUDS has exhibited consistently low radiation exposure amongst all age groups. Moving forward, we have the foundation and flexibility to create an imaging protocol for pediatric VUDS, while taking more calculated steps toward incorporating ALARA, as low as reasonably achievable, principles. A protocol adhering to the ALARA principle could provide consistency across institutions and aid in multi-institutional studies.

Radiation exposure in multiple hereditary exostoses: A retrospective review

Background

Exposure to ionizing radiation in patients with Multiple Hereditary Exostoses (MHE) is inevitable and necessary for the diagnosis and treatment of MHE. Radiation exposure has many potentially dangerous consequences, including the increased risk of developing cancer. This is especially concerning in the pediatric patient population since children are more likely to develop adverse effects from radiation than adults. This study aimed to quantify radiation exposure over a five-year period among patients diagnosed with MHE since such information is not currently available in the literature.

Methods

Diagnostic radiographs, computed tomography (CT) scans, nuclear medicine studies, and intraoperative fluoroscopy exposures were analyzed for radiation exposure in 37 patients diagnosed with MHE between 2015 and 2020.

Results

Thirty-seven patients with MHE underwent 1200 imaging studies, 976 of which were related to MHE and 224 unrelated to MHE. The mean estimated MHE cumulative radiation dose per patient was 5.23 mSv. Radiographs related to MHE contributed the most radiation. Patients from the ages of 10- to 24-years-old received the most imaging studies and exposure to ionizing radiation, especially compared to those under age 10 (P = 0.016). The 37 patients also received a total of 53 surgical-excision procedures, with a mean of 1.4 procedures per person.

Conclusions

MHE patients are exposed to increased levels of ionizing radiation secondary to serial diagnostic imaging, with those ages 10-24 years old being exposed to significantly higher doses of radiation. Because pediatric patients are more sensitive to radiation exposure and are at an overall higher risk, the use of radiographs should always be justified in those patients.

Effective radiation dose of skeletal surveys performed for suspected physical abuse

BACKGROUND

A skeletal survey is an important diagnostic tool for patients presenting with suspected physical abuse. A relatively recent change in guidelines for skeletal surveys by the Royal College of Radiologists (RCR) in 2017 has led to more initial and follow-up images for these patients, which would be expected to have led to an increase in effective radiation dose.

OBJECTIVE

To estimate the effective dose following the change in guidelines and to ascertain the difference between doses before and after the change in guidelines.

MATERIALS AND METHODS

Data were collected retrospectively on children younger than 3 years old referred for skeletal surveys for suspected physical abuse at a tertiary paediatric centre. A Monte Carlo radiation patient dose simulation software, PCXMC v 2.0.1, was used to estimate the effective dose, expressed in millisieverts (mSv).

RESULTS

Sixty-eight children underwent skeletal surveys for suspected physical abuse. The total estimated effective dose for skeletal surveys with the previous RCR guidelines was found to be 0.19 mSv. For initial skeletal surveys with the current RCR guidelines, the estimated effective radiation dose was 0.19 mSv. Eighteen children had both initial and follow-up skeletal surveys as indicated by the current RCR guidelines, with an estimated effective total radiation dose of 0.26 mSv.

CONCLUSION

Skeletal surveys deliver a relatively low estimated effective radiation dose equivalent to 1 month of United Kingdom background radiation, with no significant change in dose following the change in guidelines. Therefore, the benefits of having a skeletal survey outweigh the main radiation risk. However, accurate data regarding the radiation dose are important for clinicians consenting parents/guardians for imaging in suspected physical abuse.

ALADA Dose Optimization in the Computed Tomography of the Temporal Bone: The Diagnostic Potential of Different Low-Dose CT Protocols

Objective: Repeated computed tomography (CT) is essential for diagnosis, surgical planning and follow-up in patients with middle and inner ear pathology. Dose reduction to “as low as diagnostically acceptable” (ALADA) is preferable but challenging. We aimed to compare the diagnostic quality of images of subtle temporal bone structures produced with low doses (LD) and reference protocols (RP). Methods: Two formalin-fixed human cadaver heads were scanned using a 64-slice CT scanner and cone-beam CT (CBCT). The protocols were: RP (120 kV, 250 mA, CTDIvol 83.72 mGy), LD1 (100 kV, 80 mA, CTDIvol 26.79 mGy), LD2 (100 kV, 35 mA, CTDIvol 7.66 mGy), LD3 (80 kV, 40 mA, CTDIvol 4.82 mGy), and CBCT standard protocol. Temporal bone structures were assessed using a 5-point scale. Results: A median score of ≥2 was achieved with protocols such as the tendons of m. tensor tympani (RP/LD1/LD2/CBCT) and m. stapedius (CBCT), the incudostapedial joint (RP/LD1/CBCT), the incudomalleolar joint (RP/LD1/LD2/CBCT), the stapes feet (RP/LD1/CBCT), the stapes head (RP/LD1/LD2/CBCT), the tympanic membrane (RP/LD1/LD2/CBCT), the lamina spiralis ossea (none), the chorda tympani (RP/LD1/CBCT), and the modiolus (RP/LD1/LD2/CBCT). Adaptive statistical iterative reconstructions did not show advantages over the filtered back projection. Conclusions: LD protocols using a CTDIvol of 7.66 mGy may be sufficient for the identification of temporal bone structures.

Vertebral fracture assessment (VFA) for monitoring vertebral reshaping in children and adolescents with osteogenesis imperfecta treated with intravenous neridronate

PURPOSE

The study was aimed at monitoring vertebral bodies changes with the use of Vertebral Fracture Assessment (VFA) in children and adolescents affected by osteogenesis imperfecta (OI) during treatment with intravenous neridronate.

METHODS

60 children and adolescents (35 males and 25 females; age 1-16 years) with OI type I, III and IV were included in the study. Intravenous neridronate was administered at the dose of 2 mg/kg every 3 months in all patients. Lumbar spine (LS) bone mineral density (BMD) and VFA by dual X-ray absorptiometry (DXA) were assessed every 6 months up to 24 months during treatment. VFA with vertebral morphometry (MXA) was used to calculate the three indices of vertebral deformity: wedging, concavity and crushing. Serum calcium, phosphate, parathyroid hormone (PTH), 25-hydroxy-vitamin D [25(OH)D], total alkaline phosphatase (ALP), bone alkaline phosphatase (BALP) and urinary C-terminal telopeptide of type 1 collagen (CTx) were measured at any time point.

RESULTS

Mean LS BMD values significantly increased at 24 months compared to baseline (p < 0.0001); the corresponding Z-score values were -1.28 ± 1.23 at 24 months vs -2.46 ± 1.25 at baseline; corresponding mean Bone Mineral Apparent Density (BMAD) values were 0.335 ± 0.206 vs 0.464 ± 0.216. Mean serum levels of ALP, BALP and CTx significantly decreased from baseline to 24 months. By MXA, we observed a significant 19.1% reduction of the mean wedging index of vertebral reshaping at 12 months, and 38.4% at 24 months (p < 0.0001) and of the mean concavity index (16.3% at 12 months and 35.9% at 24 months; p < 0.0001). Vertebral reshaping was achieved for 66/88 (75%) wedge fractures and 59/70 (84%) concave fractures, but there were 4 incident mild fractures. Finally, VF rate was reduced at 24 months compared to baseline: 37/710 (5.2%) vs 158/710 (22.2%).

CONCLUSION

Our study demonstrates the utility of VFA as a safe and alternative methodology in the follow-up of children and adolescents with OI.

Radiation doses in diagnostic imaging for suspected physical abuse

OBJECTIVE

To measure the actual radiation dose delivered by imaging techniques commonly used in the radiography of suspected physical abuse and to make this information available to health professionals and families.

METHODS

Data were collected retrospectively on children under 3 years referred for skeletal surveys for suspected physical abuse, non-contrast CT head scan or radionuclide imaging of the bones in Starship Children's Hospital, Auckland, New Zealand from January to December 2015. Patient size-specific conversion coefficients were derived from International Commission on Radiologic Protection tissue weighting factors and used to calculate effective dose.

RESULTS

Seventy-one patients underwent an initial skeletal survey, receiving a mean effective dose of 0.20 mSv (95% CI 0.18 to 0.22). Sixteen patients had a follow-up survey with a mean effective dose of 0.10 mSv (95% CI 0.08 to 0.11). Eighty patients underwent CT head which delivered a mean effective dose of 2.49 mSv (95% CI 2.37 to 2.60). Thirty-nine patients underwent radionuclide bone imaging which delivered a mean effective dose of 2.27 mSv (95% CI 2.11 to 2.43).

CONCLUSIONS

In a paediatric centre, skeletal surveys deliver a relatively low effective radiation dose, equivalent to approximately 1 month of background radiation. Non-contrast CT head scan and radionuclide bone imaging deliver similar doses, equivalent to approximately 1 year of background radiation. This information should be considered when gaining informed consent and incorporated in patient education handouts.

Diagnostic accuracy of DXA compared to conventional spine radiographs for the detection of vertebral fractures in children

OBJECTIVES

In children, radiography is performed to diagnose vertebral fractures and dual energy x-ray absorptiometry (DXA) to assess bone density. In adults, DXA assesses both. We aimed to establish whether DXA can replace spine radiographs in assessment of paediatric vertebral fractures.

METHODS

Prospectively, lateral spine radiographs and lateral spine DXA of 250 children performed on the same day were independently scored by three radiologists using the simplified algorithm-based qualitative technique and blinded to results of the other modality. Consensus radiograph read and second read of 100 random images were performed. Diagnostic accuracy, inter/intraobserver and intermodality agreements, patient/carer experience and radiation dose were assessed.

RESULTS

Average sensitivity and specificity (95 % confidence interval) in diagnosing one or more vertebral fractures requiring treatment was 70 % (58-82 %) and 97 % (94-100 %) respectively for DXA and 74 % (55-93 %) and 96 % (95-98 %) for radiographs. Fleiss' kappa for interobserver and average kappa for intraobserver reliability were 0.371 and 0.631 respectively for DXA and 0.418 and 0.621 for radiographs. Average effective dose was 41.9 μSv for DXA and 232.7 μSv for radiographs. Image quality was similar.

CONCLUSION

Given comparable image quality and non-inferior diagnostic accuracy, lateral spine DXA should replace conventional radiographs for assessment of vertebral fractures in children.

KEY POINTS

• Vertebral fracture diagnostic accuracy of lateral spine DXA is non-inferior to radiographs. • The rate of unreadable vertebrae for DXA is lower than for radiographs. • Effective dose of DXA is significantly lower than radiographs. • Children prefer DXA to radiographs. • Given the above, DXA should replace radiographs for paediatric vertebral fracture assessment.

Effective Radiation Dose in a Skeletal Survey Performed for Suspected Child Abuse

Effective dose of a skeletal survey in infants using digital radiography was estimated to be 0.2 mSv using Monte Carlo simulation. Radiation risk from this procedure is, therefore, low. Radiation concern should not be an overriding factor when deciding whether skeletal survey is needed in cases of possible physical abuse.