PURPOSE:To quantify the degree of correlation between pediatric radiation exposure rates and commonly used body size surrogates: anteroposterior (AP) or lateral (LAT) body thickness, weight, height, body mass index (BMI), body surface area (BSA), and age, for general fluoroscopy (GF) and cardiac fluoroscopically guided interventional (cardiac FGI) examinations, as a way to identify the most predictive surrogate to optimize dose management and exposure control across a wide range of pediatric body sizes. METHODS:This retrospective study included 6447 GF examinations, from 4452 pediatric patients, and 2968 cardiac FGI examinations, from 1471 patients, aged from birth to 21 years. Reference air kerma (RAK) data, collected from a radiation dose index monitoring database, were corrected using calibration measurements with accuracy better than ± 5%. Exposure rate was calculated as RAK divided by total fluoroscopy time. Patient body size surrogates: measured AP or LAT thickness, age, weight, height, BMI, and BSA were extracted or computed from recorded data. Correlations between log-transformed exposure rates and body size surrogates were evaluated using Pearson's correlation coefficients. Steiger's Z-test was applied to assess statistically significant differences between dependent correlations. RESULTS:For GF examinations, AP thickness correlated most strongly with exposure rate (r = 0.691), followed by BSA (r = 0.574) and weight (r = 0.568). BMI showed the weakest correlation (r = 0.446). For cardiac FGI examinations, weight demonstrated the highest correlation with exposure rate in both frontal (r = 0.689) and LAT (r = 0.794) planes, with BSA and LAT thickness performing similarly. All other correlations were significantly lower (p < 0.001). The superior performance of AP thickness in GF reflects its direct relationship to X-ray attenuation, whereas variable geometry and positioning during cardiac FGI favor weight as a more stable predictor. CONCLUSIONS:For pediatric fluoroscopy, AP thickness best predicts exposure rate in GF, while weight is the most reliable surrogate for cardiac FGI procedures. Selecting modality-specific size metrics enhances pediatric dose optimization and supports consistent radiation exposure management across all patient sizes.

Advancements in cardiac catheterization have improved survival for pediatric congenital heart disease patients, but the associated ionizing radiation risks necessitate ethical consideration. This study presents an empirical model to establish reference air kinetic energy released per unit mass (KERMA) and air KERMA area product, also referred to as dose area product, alert levels based on pediatric patient size during diagnostic or interventional cardiac catheterization. Recognizing the significant size variations among pediatric patients, the model provides a universal application for institutions to set quality assurance programs to prevent overexposure. Developed from 3131 unique procedures, the model uses linear regression of logarithmic reference air KERMA and dose area product against the patient's lateral thickness of the thorax for various procedural categories, setting alert levels at the top 95% and 99% of patient data. This allows institutions to tailor dose alert levels to their specific pediatric populations.

Purpose: To assess the diagnostic confidence of intraoral radiographic image quality while reducing the pediatric patient's radiation exposure using a longer position indicating device (PID), additional X-ray beam filtration and rectangular collimation while using modern, lower-power intraoral dental X-ray units.Methods: A randomized prospective study scored bitewing intraoral dental images based on relevant clinical features. Observer studies with pediatric dentists and dental residents were conducted to verify whether diagnostic confidence remained unchanged after dose reduction modifications. The study involved a two-phase investigation to determine: (1) the best thickness of aluminum (Al) 2024-T3 alloy filter and (2) required increased exposure time to maintain intraoral radiographic image quality. A 30 cm PID with a rectangular collimator was used to further manage patient dose. For each phase, images from 125 patients were collected from February 2017 to September 2018 and analyzed.Results: The results from the observer study using a 30 cm PID, 1.02 mm thick Al alloy filter, and a rectangular collimator resulted in a patient dose reduction between 64 percent (exposure time of 400 msec) to 77 percent (250 msec), without any statis- tically significant effect to the diagnostic confidence of the observers in evaluating the reduced radiation images.Conclusion: Long recognized dose reduction methods, when implemented on a modern, low-power intraoral dental X-ray unit, do not impact confidence in bite- wing diagnostic images, but substantially reduce patient dose and should be adopted to increase patient safety, especially for children.

Background Diagnostic reference levels (DRLs) and achievable doses (ADs) were developed for the 10 most commonly performed pediatric CT examinations in the United States using the American College of Radiology Dose Index Registry. Purpose To develop robust, current, national DRLs and ADs for the 10 most commonly performed pediatric CT examinations as a function of patient age and size. Materials and Methods Data on 10 pediatric (ie, patients aged 18 years and younger) CT examinations performed between 2016 and 2020 at 1625 facilities were analyzed. For head and neck examinations, dose indexes were analyzed based on patient age; for body examinations, dose indexes were analyzed for patient age and effective diameter. Data from 1 543 535 examinations provided medians for AD and 75th percentiles for DRLs for volume CT dose index (CTDIvol), dose-length product (DLP), and size-specific dose estimate (SSDE). Results Of all facilities analyzed, 66% of the facilities (1068 of 1625) were community hospitals, 16% (264 of 1625) were freestanding centers, 9.5% (154 of 1625) were academic facilities, and 3.5% (57 of 1625) were dedicated children's hospitals. Fifty-two percent of the patients (798 577 of 1 543 535) were boys, and 48% (744 958 of 1 543 535) were girls. The median age of patients was 14 years (boys, 13 years; girls, 15 years). The head was the most frequent anatomy examined with CT (876 655 of 1 543 535 examinations [57%]). For head without contrast material CT examinations, the age-based CTDIvol AD ranged from 19 to 46 mGy, and DRL ranged from 23 to 55 mGy, with both AD and DRL increasing with age. For body examinations, DRLs and ADs for size-based CTDIvol, SSDE, and DLP increased consistently with the patient's effective diameter. Conclusion Diagnostic reference levels and achievable doses as a function of patient age and effective diameter were developed for the 10 most commonly performed CT pediatric examinations using American College of Radiology Dose Index Registry data. These benchmarks can guide CT facilities in adjusting pediatric CT protocols and resultant doses for their patients. © RSNA, 2021 An earlier incorrect version appeared online. This article was corrected on October 29, 2021.

The purpose of this study was to provide an empirical model to develop reference air kerma (RAK) alert levels as a function of patient thickness or age for pediatric fluoroscopy for any institution to use in a Quality Assurance program. RAK and patient thickness were collected for 10&663 general fluoroscopic examinations and 1500 fluoroscopically guided interventions (FGIs). RAK and patient age were collected for 6137 fluoroscopic examinations with mobile-C-arms (MC). Coefficients of linear regression fits of logarithmic RAK as a function of patient thickness or age were generated for each fluoroscopy group. Regression fits of RAK for 50%, 90%, and 98% upper prediction levels were used as inputs to derive an empirical formula to estimate alert levels as a function of patient thickness. A methodology is presented to scale results from this study for any patient thickness or age for any institution, for example, the patient thickness dependent RAK alert level at the top 1% of expected RAK can be set using the 98% upper prediction interval boundary given by: RAK 98 % = e m . x avg + s 98 . c ̂ ${\rm{RAK}}_{98\% } = {e}^{m.{x}_{{\rm{avg}}} + {s}_{98}.\hat{c}}\ $ , where xavg is the institute's average patient thickness or age, and c ̂ $\hat{c}$ is the intercept based on the average RAK of the patient population calculated as c ̂ = ln ( RAK avg ) - m . x avg . RA K avg $\hat{c} = \ln ( {{\rm{RAK}}_{{\rm{avg}}}} )\ - m.{x}_{{\rm{avg}}}{\rm{.RA}}{{\rm{K}}}_{{\rm{avg}}}$ is the institution's average RAK (mGy). m and s98 are constants presented for each type of fluoroscope and RAK group and represent slope of the fit and scale factor, respectively. An empirical equation, which estimates alert levels expressed as air Kerma without backscatter at the interventional reference point as a function of patient thickness or age is provided for each fluoroscopic examination type. The empirical equations allow any facility with limited data to scale the results of this study's single facility data to model their practice's unique RAK alert levels and patient population demographics to establish pediatric alert levels for fluoroscopic procedures.

Objective. To compare technical errors in bitewing radiographs acquired with round vs rectangular collimation in a hospital Study Design. A retrospective chart review was conducted of 176 digital bitewing radiographs exposed with round collimation and 106 exposed with rectangular collimation. The number of re-exposures was calculated, and errors in central ray entry (CRE; "cone cuts"), horizontal and vertical positioning, and angulation were measured. Results. There were no greater re-exposures but significantly more CRE errors with rectangular collimation (21.7%; n = 23; 95% confidence interval [CI], 13.9%-30.0%) than with round collimation (3.4%; n = 6; 95% CI, 0.7%-6.1%). CRE error location, horizontal positioning errors, and size of horizontal overlapped contacts were statistically different but not clinically important. Conclusions. Use of rectangular collimation resulted in increased CRE errors but no other clinically significant problems. This technique should be used to reduce radiation exposure to patients. (Oral Surg Oral Med Oral Pathol Oral Radiol 2022;133:333-342)

Gonadal shields consisting of lead-equivalent material have been used in radiography since the early 1950s [1,2]. When this practice began, radiography used entrance air kerma values 25 times greater than current values [3,4] for both adult and pediatric patients. The current era of reduced patient doses and an improved understanding of radiation effects have raised questions about the effectiveness of gonadal shielding [5-7]. One of these questions concerns the use of gonadal shielding with the management of the patient's radiation dose by the x-ray machine's automatic exposure control (AEC).

Purpose Recently, medical professionals have reconsidered the practice of routine gonadal shielding for radiographic examinations. The objective of this study was to evaluate the gonadal dose reduction achievable with gonadal shields in the primary beam during abdominal/pelvic radiographic examinations under ideal and non‐ideal shielding placement. Methods CT scans of CIRS anthropomorphic phantoms were used to perform voxelized Monte Carlo simulations of the photon transport during abdominal/pelvic radiographic examinations with standard filtration and 0.1 mm Cu + 1 mm Al added filtration to estimate gonadal doses for an adult, 5 yr old, and newborn phantom with and without gonadal shields. The reduction in dose when the shields were not placed at the ideal locations was also evaluated. The ratio of the number of scattered‐to‐primary photons (SPR) across the anteroposterior (AP) dimension of the phantoms was also reported. Results The simulated dose reduction with ideal shielding placement for the testes and ovaries ranged from 80% to 90% and 55% to 70% respectively. For children, a misalignment of the shield to the gonad of 4 cm reduced the measured dose reduction to the gonads to <10%. For adults, this effect did not occur until the misalignment increased to ~6 cm. Effects of dose reduction with and without the gonadal shields properly placed were similar for standard filtration and added filtration. SPR at the level of the testes was consistently <1 for all phantoms. SPR for ovaries was ~1.5 for the adult and 5‐yr old, and ~1 for the newborn phantom. Conclusion Dose reduction with ideal alignment of the simulated gonadal shield to the gonads in this study was greater for the testes than the ovaries; both reductions were substantial. However, the dose reductions were greatly reduced (to <10%) for both sexes with misalignment of the gonads to the shields by 4 cm for children and 6 cm for adults.

Quantification of system performance of fluoroscopes by the medical physicist at an elevated level is necessary to provide useful, clinically relevant information to the fluoroscopist. This chapter discusses the need for functional testing of automatic brightness control/dose management systems (ABCDMS), due to the wide variety of acquisition techniques that are available. The limited availability of the clinical fluoroscope makes it impossible to check the response of the ABCDMS to all combinations of clinical examinations and thicknesses of patient. The chapter also discusses the metrics for automated collection and analysis of performance data. It suggests standardized phantoms and software analysis tools that allow quantitative analysis of both high contrast resolution and low contrast resolution. The medical physicist must be given adequate time to interpret and respond to equipment configuration issues and/or misunderstanding of operators to improve patient care by properly managing patient radiation doses and the quality of the images produced.

Poster: EuroSafe Imaging 2020 / ESI-03521 / Who CARES? Communication Challenges and Available Resources When Discontinuing Gonadal Shielding by: R. Marsh1, S. McKenney2, D. P. Frush3, K. J. Strauss4, B. Schueler5, D. Gress6, C. H. McCollough7; 1University of Colorado School of Medicine Aurora, CO/US, 2Stanford University Stanford, CA/US, 3Duke University Durham, NC/US, 4 Cincinnati, OH, OH/US, 5Mayo Clinic Rochester/US, 6American College of Radiology Reston/US, 7Mayo Clinic College of Medicine Rochester, MN/US

Abstract Careful protocol selection is required during intraoperative three‐dimensional (3D) imaging for spine surgery to manage patient radiation dose and achieve clinical image quality. Radiation dose and image quality of a Medtronic O‐arm commonly used during spine surgery, and a Philips hybrid operating room equipped with XperCT C‐arm 3D cone‐beam CT (hCBCT) are compared. The mobile O‐arm (mCBCT) offers three different radiation dose settings (low, standard, and high), for four different patient sizes (small, medium, large, and extra large). The patient's radiation dose rate is constant during the entire 3D scan. In contrast, C‐CBCT spine imaging uses three different field of views (27, 37, and 48 cm) using automatic exposure control (AEC) that modulates the patient's radiation dose rate during the 3D scan based on changing patient thickness. hCBCT uses additional x‐ray beam filtration. Small, medium, and large trunk phantoms designed to mimic spine and soft tissue were imaged to assess radiation dose and image quality of the two systems. The estimated measured “patient” dose for the small, medium, and large phantoms imaged by the mCBCT considering all the dose settings ranged from 9.4–27.6 mGy, 8.9–33.3 mGy, and 13.8–40.6 mGy, respectively. The “patient” dose values for the same phantoms imaged with hCBCT were 2.8–4.6 mGy, 5.7–10.0 mGy, and 11.0–15.2 mGy. The CNR for the small, medium, and large phantoms was 2.9 to 3.7, 2.0 to 3.0, and 2.5 to 2.6 times higher with the hCBCT system, respectively. Hounsfield unit accuracy, noise, and uniformity of hCBCT exceeded the performance of the mCBCT; spatial resolution was comparable. Added x‐ray beam filtration and AEC capability achieved clinical image quality for intraoperative spine surgery at reduced radiation dose to the patient in comparison to a reference O‐arm system without these capabilities.