Exploring Dental Anatomy: An Ex Vivo Comparative Study Between Photon‐Counting Detector CT and Cone‐Beam CT

To assess the diagnostic performance of photon-counting detector computed tomography (PCD-CT) and cone-beam computed tomography (CBCT) at dose-matched radiation levels (high, standard, and low) for detecting and evaluating simulated endodontic conditions, treatments, and associated complications. Sixteen extracted third molars with eight endodontic tasks were imaged using PCD-CT and CBCT. Qualitative (image quality, artifact susceptibility, diagnostic interpretability) and quantitative (endodontic working length) parameters were assessed by two observers using a five-point Likert scale. Descriptive statistics and weighted kappa (κ) were used for data analysis. High- and standard-dose PCD-CT demonstrated superior image quality and anatomical visualization compared to CBCT (median 5, IQR 5-5; κ = 1.0; all p < 0.001). Low-dose PCD-CT remained diagnostically robust, outperforming CBCT, except in root canal visualization, where both performed similarly. Diagnostic accuracy of pathologies and complications was slightly higher with PCD-CT (80-88%) than with CBCT (75-88%). Endodontic working length measurements were consistently accurate across all protocols, with near-perfect inter-observer agreement (κ = 0.84-0.86, all p < 0.001). PCD-CT demonstrated superior diagnostic performance over CBCT across multiple endodontic tasks, particularly at high and standard doses. Even at low doses, PCD-CT maintained robust accuracy and image quality, outperforming dose-matched CBCT in most parameters. Endodontic working length assessment was equally reliable across both modalities. Overall, PCD-CT offers diagnostic advantages over CBCT, particularly in challenging cases involving complex anatomy or high-density materials. Its effective performance at lower radiation levels emphasizes its clinical potential and supports broader implementation in dentomaxillofacial diagnostics.

Cone-beam versus photon-counting detector CT: Influence of dose variations on the detection of simulated mandibular osseous lesions.

PurposeTo compare cone-beam computed tomography (CBCT) with photon-counting detector computed tomography (PCD-CT) at equivalent radiation doses, focusing on qualitative and quantitative parameters relevant to dental implant surgery.MethodsThis ex vivo comparative study of porcine specimens assessed five imaging protocols with both CBCT and PCD-CT at three effective radiation dose levels (high: 360µSv, standard: 145µSv, low: 20µSv) to evaluate image quality, artifact burden, metal artifact susceptibility, and quantitative bone measurements in the mandibular region. Three blinded readers analyzed the data using a 5-point Likert scale (5 = highest to 1 = lowest rating) and performed linear bone measurements at implant planning sites. Statistical analysis included descriptive statistics and inter-reader reliability assessment using intraclass correlation coefficients (ICC).ResultsEach reader evaluated 30 data sets (12 CBCT, 18 PCD-CT), with 24 implant planning sites per imaging protocol. High-dose PCD-CT demonstrated the best image quality and diagnostic interpretability (4.89 ± 0.27), followed by standard-dose PCD-CT and CBCT (4.50 ± 0.73; 4.33 ± 0.61), with low-dose protocols showing intermediate quality with higher artifact burden. In comparison to CBCT, PCD-CT demonstrated superior performance in reducing implant-induced artifacts across all protocols. Quantitative bone measurements showed minimal variability, meeting clinical precision requirements for computer-assisted implant surgery. Both qualitative (ICCs:0.70–0.89; p < 0.001) and quantitative (ICCs:0.79–1; p < 0.001) analyses demonstrated high reliability, regardless of the reader’s experience.ConclusionsPCD-CT demonstrated superior image quality and reduced artifacts compared with CBCT at all radiation dose levels. These findings highlight PCD-CT’s potential to enhance implant planning and improve clinical outcomes with reduced radiation exposure while maintaining diagnostic accuracy.

Previous studies have shown improved image quality in pediatric cardiac imaging using photon-counting detector CT (PCDCT). However, these studies did not evaluate image quality and radiation dose when utilizing the full spectral capabilities of PCDCT scanners. The full spectral capability of PCDCT scanners allows the generation of the entire array of mono-energetic reconstructions, virtual non-contrast (VNC) images, and iodine maps, which have potential advantages in evaluating complex congenital heart disease. For example, following complex congenital cardiac repairs, when distinguishing intraluminal or soft tissue calcifications from contrast, or when evaluating intrastent thrombus. To compare image quality and radiation dose between high-pitch cardiac CT using full spectral PCDCT and dual-source energy-integrating detector CT (EIDCT). This retrospective, IRB-approved study analyzed high-pitch cardiac CTs from January 2021 to October 2023 in pediatric patients (< 18years). Patients were scanned using either PCDCT with full spectral technique ("QuantumPlus") or EIDCT. Radiation doses were measured by CT dose index (CTDI) and dose-length product (DLP). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were also calculated, and image quality was assessed using a 5-point Likert scale. Statistical analysis included unpaired T-test, Shapiro-Wilk test, Mann-Whitney test, and kappa coefficients for interrater agreement. Two hundred patients were evaluated, with 100 scanned on PCDCT and 100 on EIDCT. In the PCDCT scanner, 47/100 (47%) were male and 53/100 were female (53%) (P = 0.01). In the EIDCT scanner, 65/100 were male (65%) and 35/100 (35%) were female (P = 0.01). In the PCDCT scanner, 68/100 (68%) (P = 0.05) were ≤ 12months, and 32/100 (32%) (P = 0.05) were > 12months. In the EIDCT, 80/100 (80%) (P = 0.05) were ≤ 12months, and 20/100 (20%) (P = 0.05) were > 12months.In patients ≤ 12months, the CNR were 31.61 in the PCDCT group and 32.14 in the EIDCT group (P = 0.39). For those > 12months, CNR were 30.07 for PCDCT and 25.27 for EIDCT (P = 0.17).In patients ≤ 12months, SNR was significantly lower (P < 0.0001) in PCDCT, compared to EIDCT for the teres minor muscles, while in patients > 12months, SNR was not significantly lower (P = 0.89); SNR was similar between scanners. Radiation doses were significantly higher for PCDCT across both age groups (P < 0.0001). High-pitch cardiac CT with PCDCT using spectral processing resulted in higher radiation doses and lower SNR in infants compared to EIDCT.

Quantitative lung imaging is utilized to understand, characterize, and monitor lung disease and response to interventions. X-ray computed tomography has remained the modality of choice for clinical lung assessment, and photon counting detector-computed tomography (PCD-CT) is the latest advancement. PCD-CT provides increased spatial and contrast resolution, decreased image noise and artifacts (such as beam hardening) and, thus, a potential for enhanced image quality for equivalent or reduced radiation dose levels. However, evaluation of the ultra-high resolution capabilities of PCD-CT for quantitative lung imaging has not yet been systematically investigated. This study aims to evaluate 2 ultra-high resolution acquisition modes and 4 reconstruction kernels for optimal quantitative chest imaging at high radiation dose (9mGy). We assess the stability of measurements across different scan modes and reconstruction kernels when the radiation dose level is reduced. A customized anthropomorphic chest phantom, containing standardized insert materials, including air, water, various density foam inserts, and a modulation transfer function (MTF) cube, was repeatedly scanned with PCD-CT (NAEOTOM Alpha; Siemens Healthineers). Two ultra-high resolution acquisition modes, quantum plus (UHRQ+) and quantum with tin filtering (UHRQSn), and 4 reconstruction kernels (Br64, Bl60, Qr60, and Qr40, all with iterative reconstruction level 3) were examined with acquisitions at 3 radiation dose levels (9.1mGy, 6.8mGy, and 3.2mGy). Quantitative density measures, airway measurements, contrast-to-noise ratio (CNR), signal-to-noise ratio (SNR), and MTF values were compared, along with the percentage change in measurement values from high to low radiation dose levels. At the highest radiation dose levels, UHRQ+ acquisition resulted in lower density values with higher SD compared with UHRQSn. UHRQ+ mode demonstrated higher CNR, SNR, and MTF values. Only UHRQ+ with Qr40 reconstruction provided accurate air measurements, both inside and outside the phantom, across all radiation dose levels. Quantitative density measurements remained highly stable (<2% change) as the radiation dose was reduced from 9.1 to 3.2mGy. Airway wall thickness, diameter, and lumen area measurements were all larger with UHRQ+ acquisition compared with UHRQSn for the high radiation dose level. At low radiation dose levels, the UHRQ+ acquisition with Br64 reconstruction maintained the highest consistency in airway metrics compared with the values from the high dose acquisition, with <5% measurement percentage change. The UHRQ+ mode is recommended for quantitative lung assessment, leveraging the PCD-CT voxel size potential (1024×1024 in plane matrix with 0.2mm slice thickness). The choice of reconstruction kernel at ultra-high resolution should be task-specific, with Qr40 being optimal for density assessment due to its accuracy in air measurement across regions and Br64 for airway assessment. The high consistency of measurements across the radiation dose levels for these kernels (<5% measurement change from 9mGy measurements) suggests that acquisition at 3mGy is sufficient for quantitative analysis.

BACKGROUND. Photon-counting detector (PCD) CT may allow lower radiation doses than used for conventional energy-integrating detector (EID) CT, with preserved image quality. OBJECTIVE. The purpose of this study was to compare PCD CT and EID CT, reconstructed with and without a denoising tool, in terms of image quality of the osseous pelvis in a phantom, with attention to low radiation doses. METHODS. A pelvic phantom comprising human bones in acrylic material mimicking soft tissue underwent PCD CT and EID CT at various tube potentials and radiation doses ranging from 0.05 to 5.00 mGy. Additional denoised reconstructions were generated using a commercial tool. Noise was measured in the acrylic material. Two readers performed independent qualitative assessments that entailed determining the denoised EID CT reconstruction with the lowest acceptable dose and then comparing this reference reconstruction with PCD CT reconstructions without and with denoising, using subjective Likert scales. RESULTS. Noise was lower for PCD CT than for EID CT. For instance, at 0.05 mGy and 100 kV with tin filter, noise was 38.4 HU for PCD CT versus 48.8 HU for EID CT. Denoising further reduced noise; for example, for PCD CT at 100 kV with tin filter at 0.25 mGy, noise was 19.9 HU without denoising versus 9.7 HU with denoising. For both readers, lowest acceptable dose for EID CT was 0.10 mGy (total score, 11 of 15 for both readers). Both readers somewhat agreed that PCD CT without denoising at 0.10 mGy (reflecting reference reconstruction dose) was relatively better than the reference reconstruction in terms of osseous structures, artifacts, and image quality. Both readers also somewhat agreed that denoised PCD CT reconstructions at 0.10 mGy and 0.05 mGy (reflecting matched and lower doses, respectively, with respect to reference reconstruction dose) were relatively better than the reference reconstruction for the image quality measures. CONCLUSION. PCD CT showed better-quality images than EID CT when performed at the lowest acceptable radiation dose for EID CT. PCD CT with denoising yielded better-quality images at a dose lower than lowest acceptable dose for EID CT. CLINICAL IMPACT. PCD CT with denoising could facilitate lower radiation doses for pelvic imaging.

BACKGROUND. Photon-counting detector (PCD) CT could be useful to help address the typically high radiation doses of conventional energy-integrating detector (EID) CT of the lumbar spine. OBJECTIVE. The purpose of our study was to compare PCD CT and EID CT of the lumbar spine, both performed using tin filtration, in terms of radiation dose and image quality. METHODS. This study included a prospective sample of 39 patients (22 men, 17 women; mean age, 27.2 years) who underwent investigational PCD CT of the lumbar spine as part of a separate study and a retrospective sample of 39 patients (22 men, 17 women; mean age, 34.9 years) who underwent clinically indicated EID CT of the lumbar spine. In both groups, all examinations were performed using unenhanced technique with tin prefiltration between June 2022 and January 2023. Patients were matched between groups using age, sex, and BMI. A custom gaussian curve-fitting algorithm was used to automatically calculate image noise, SNR, and CNR for each examination, on the basis of all voxels within the image set. Three radiologists independently reviewed examinations to perform a subjective visual assessment of visualization of trabecular architecture, cortical bone, neuroforaminal content, paraspinal muscles, and intervertebral disk, as well as overall image quality, using a 4-point Likert scale (1 = poor, 4 = excellent). PCD CT and EID CT examinations were compared. RESULTS. Mean CTDIvol was 4.4 ± 1.0 (SD) mGy for PCD CT versus 11.1 ± 1.9 mGy for EID CT (p < .001). Mean size-specific dose estimate (SSDE) was 6.2 ± 1.0 (SD) mGy for PCD CT versus 14.2 ± 1.8 mGy for EID CT (p < .001). PCD CT and EID CT examinations were not significantly different in terms of image noise or SNR (both p > .05). PCD CT, in comparison with EID CT, showed significantly higher CNR (mean ± SD, 33.6 ± 3.3 vs 29.3 ± 4.1; p < .001). For all three readers, the median score for overall image quality was 4 (range, 3-4) for both PCD CT and EID CT. PCD CT and EID CT examinations showed no significant difference in terms of any qualitative measure for any reader (all p > .05). CONCLUSION. PCD CT, in comparison with EID CT, yielded significantly lower radiation dose with preserved image quality. CLINICAL IMPACT. The findings support expanded use of PCD CT for lumbar spine evaluation.

Hardening the x-ray beam, tin prefiltration is established for imaging of high-contrast subjects in energy-integrating detector computed tomography (EID-CT). With this work, we aimed to investigate the dose-saving potential of spectral shaping via tin prefiltration in photon-counting detector CT (PCD-CT) of the temporal bone. Deploying dose-matched scan protocols with and without tin prefiltration on a PCD-CT and EID-CT system (low-/intermediate-/full-dose: 4.8/7.6-7.7/27.0-27.1 mGy), 12 ultra-high-resolution examinations were performed on each of 5 cadaveric heads. While 120 kVp was applied for standard imaging, the protocols with spectral shaping used the highest potential available with tin prefiltration (EID-CT: Sn 150 kVp, PCD-CT: Sn 140 kVp). Contrast-to-noise ratios and dose-saving potential by spectral shaping were computed for each scanner. Three radiologists independently assessed the image quality of each examination with the intraclass correlation coefficient being computed to measure interrater agreement. Regardless of tin prefiltration, PCD-CT with low (171.2 ± 10.3 HU) and intermediate radiation dose (134.7 ± 4.5 HU) provided less image noise than full-dose EID-CT (177.0 ± 14.2 HU; P < 0.001). Targeting matched image noise to 120 kVp EID-CT, mean dose reduction of 79.3% ± 3.9% could be realized in 120 kVp PCD-CT. Subjective image quality of PCD-CT was better than of EID-CT on each dose level ( P < 0.050). While no distinction was found between dose-matched PCD-CT with and without tin prefiltration ( P ≥ 0.928), Sn 150 kVp EID-CT provided better image quality than 120 kVp EID-CT at high and intermediate dose levels ( P > 0.050). The majority of low-dose EID-CT examinations were considered not diagnostic, whereas PCD-CT scans of the same dose level received satisfactory or better ratings. Interrater reliability was excellent (intraclass correlation coefficient 0.903). PCD-CT provides superior image quality and significant dose savings compared with EID-CT for ultra-high-resolution examinations of the temporal bone. Aiming for matched image noise, high-voltage scan protocols with tin prefiltration facilitate additional dose saving in EID-CT, whereas superior inherent denoising decreases the dose reduction potential of spectral shaping in PCD-CT.

Photon counting detector (PCD) CT benefits from reduced noise compared with conventional energy-integrating detector (EID) CT, which should translate to improved image quality and reduced radiation exposure for pediatric patients undergoing chest CT with IV contrast. To determine the differences in radiation exposure and image quality of PCD CT and EID CT in pediatric chest CT with intravenous (IV) contrast. In this institutional review board-approved retrospective observational study, 20 scan pairs (20 PCD CT; 20 EID CT) for children who underwent chest CT with IV contrast on both a PCD CT (Siemens NAEOTOM Alpha) and an EID CT (Siemens SOMATOM Definition Edge or Force) within 12months were reviewed independently by three pediatric radiologists for three subjective quality features on 5-point Likert scales: overall quality, small structure delineation, and motion artifact. Objective measures of image quality (image noise, signal-to-noise ratio, and contrast-to-noise ratio) were assessed by a single radiologist in several locations in the chest through region of interest measurement of Hounsfield units (HU) and standard deviation. Patient-related and radiation exposure parameters were collected for each scan and summarized with median and interquartile range (IQR). The Wilcoxon rank-sum test was utilized to compare groups. A P < 0.05 indicated statistical significance. Inter-observer agreement of subjective image quality metrics was analyzed using weighted kappa. Age (14.2years vs 13.8years, P= 0.15), height (P= 0.13), weight (P= 0.21), and BMI (P = 0.24) did not significantly differ between groups. There were 10 male and 3 female patients. Compared to EID CT, PCD CT showed lower radiation exposure parameters including volumetric CT dose index, 1.7mGy (IQR 1.1-2.4mGy) vs 3.8mGy (IQR 2.0-4.7mGy) (P< 0.01), and size-specific dose estimate, 2.6mGy (IQR 1.8-3.1mGy) vs 5.0mGy (IQR 3.3-6.2mGy) (P< 0.01). Objective image quality of lung parenchyma was improved on the PCD CT scanner, including image noise 119.5 HU (IQR 95.4-135.7 HU) vs 143.1 HU (IQR 125.4-169.8 HU) (P < 0.01), signal-to-noise ratio (SNR) -6.1 (IQR -8.4 to -4.8) vs -4.9 (IQR -5.6 to -3.8) (P= 0.01), and contrast-to-noise ratio -63.9 (-84.1 to -57.5) vs -60.5 (-76.3 to -52.5) (P = 0.01). Motion artifact was improved on the PCD CT scanner (P< 0.01). No significant differences in overall image quality or small structure delineation were identified (P= 0.06 and P= 0.31). PCD CT pediatric chest CT had significantly reduced radiation exposure, improved image quality, and reduced motion artifact compared with EID CT.

To investigate the image quality and the performance of photon-counting detector (PCD) CT compared to conventional energy-integrating detector (EID) CT in identifying subsolid nodule (SSN) characteristics. Participants with SSNs who underwent same-day EID CT and PCD CT between October 2023 and April 2024 were prospectively included. The 1.0 mm EID CT images and, subsequently, 1.0 mm, 0.4 mm, and 0.2 mm PCD CT images were reviewed to assess image noise and subjective image quality on a 5-point Likert scale. SSN characteristics, including lobulation, spiculation, pleural retraction, air cavities, intra-nodular vessel signs, internal vascular changes, and heterogeneous solid components, were evaluated. Additionally, a step-by-step observation and comparison method was used to determine the presence of any additional characteristics. Forty-eight participants (mean age: 56 ± 11 years; 16 males) with 89 SSNs were included. PCD CT significantly reduced radiation dose when using matched scans (1.79 ± 0.39 vs 2.17 ± 0.57 mSv, p < 0.001). Compared to 1.0 mm EID CT, 1.0 mm PCD CT images exhibited significantly lower objective image noise and higher subjective image quality (all p < 0.001). Compared to EID CT, PCD CT demonstrated enhanced visualization of subtle characteristics, except for lobulation, with a 0.4 mm section thickness offering a favorable balance between ultra-high resolution and perceived image quality for radiologists. PCD CT facilitated radiation dose reduction and outperformed conventional EID CT in terms of image quality and visualization of SSN characteristics. Question PCD CT, featuring ultra-high-resolution mode acquisition and a thinner reconstruction, has not been fully explored for characterizing SSNs. Findings Compared to EID CT, PCD CT was associated with lower objective image noise, higher subjective image quality, and superior SSN characterization. Clinical relevance PCD CT effectively reduced the radiation dose delivered to the patients and enabled more precise SSN characterization.

Radiation dose should be as low as reasonably achievable. With the invention of photon-counting detector computed tomography (PCD-CT), the radiation dose may be considerably reduced. To evaluate the potential of PCD-CT for dose reduction in pulmonary nodule visualization for human readers as well as for computer-aided detection (CAD) studies. A chest phantom containing pulmonary nodules of different sizes/densities (range 3-12 mm and -800-100 HU) was scanned on a PCD-CT with standard low-dose protocol as well as with half, quarter, and 1/40 dose (CTDIvol 0.4-0.03 mGy). Dose-matched scans were performed on a third-generation energy-integrating detector CT (EID-CT). Evaluation of nodule visualization and detectability was performed by two blinded radiologists. Subjective image quality was rated on a 5-point Likert scale. Artificial intelligence (AI)-based nodule detection was performed using commercially available software. Highest image noise was found at the lowest dose setting of 1/40 radiation dose (eff. dose = 0.01mSv) with 166.1 ± 18.5 HU for PCD-CT and 351.8 ± 53.0 HU for EID-CT. Overall sensitivity was 100% versus 93% at standard low-dose protocol (eff. dose = 0.2 mSv) for PCD-CT and EID-CT, respectively. At the half radiation dose, sensitivity remained 100% for human reader and CAD studies in PCD-CT. At the quarter radiation dose, PCD-CT achieved the same results as EID-CT at the standard radiation dose setting (93%, P = 1.00) in human reading studies. The AI-CAD system delivered a sensitivity of 93% at the lowest radiation dose level in PCD-CT. At half dose, PCD CT showed pulmonary nodules similar to full-dose PCD, and at quarter dose, PCD CT performed comparably to standard low-dose EID CT. The CAD algorithm is effective even at ultra-low doses.

BACKGROUND. Photon-counting detector (PCD) CT has been shown to reduce radiation dose and improve image quality in adult chest CT examinations; its potential impact in pediatric CT is not well documented. OBJECTIVE. The purpose of our study was to compare radiation dose, objective image quality, and subjective image quality of PCD CT and energy-integrating detector (EID) CT in children undergoing high-resolution CT (HRCT) of the chest. METHODS. This retrospective study included 27 children (median age, 3.9 years; 10 girls, 17 boys) who underwent PCD CT between March 1, 2022, and August 31, 2022, and 27 children (median age, 4.0 years; 13 girls, 14 boys) who underwent EID CT between August 1, 2021, and January 31, 2022; all examinations comprised clinically indicated chest HRCT. The patients in the two groups were matched by age and water-equivalent diameter. Radiation dose parameters were recorded. One observer placed ROIs to measure objective parameters (lung attenuation, image noise, and SNR). Two radiologists independently assessed subjective measures (overall image quality and motion artifacts) using 5-point Likert scales (1 = highest quality). Groups were compared. RESULTS. PCD CT, in comparison with EID CT, showed lower median CTDIvol (0.41 vs 0.71 mGy, p < .001), DLP (10.2 vs 13.7 mGy × cm, p = .008), size-specific dose estimate (0.82 vs 1.34 mGy, p < .001), and tube current-exposure time product (48.0 vs 202.0 mAs, p < .001). PCD CT and EID CT showed no significant difference in right upper lobe (RUL) lung attenuation (mean, -793 vs -750 HU; p = .09), right lower lobe (RLL) lung attenuation (mean, -745 vs -716 HU; p = .23), RUL image noise (mean, 55 vs 51 HU; p = .27), RLL image noise (mean, 59 vs 57 HU; p = .48), RUL SNR (mean, -14.9 vs -15.8; p = .89), or RLL SNR (mean, -13.1 vs -13.6; p = .79). PCD CT and EID CT showed no significant difference in median overall image quality for reader 1 (1.0 vs 1.0, p = .28) or reader 2 (1.0 vs 1.0, p = .17) or median motion artifacts for reader 1 (1.0 vs 1.0, p = .07) or reader 2 (1.0 vs 1.0, p = .22). CONCLUSION. PCD CT showed significantly reduced dose levels without a significant difference in objective or subjective image quality compared with EID CT. CLINICAL IMPACT. These data expand understanding of the capabilities of PCD CT and support its routine use in children.

Intra-individual comparison of image quality of the coronary arteries between photon-counting detector and energy-integrating detector CT systems

ObjectivesTo evaluate the radiation exposure, quantitative, and qualitative image quality in pediatric cardiac CT by using photon-counting detector computed tomography (PCD CT) versus energy-integrating detector CT (EID CT) in matched children.Materials and methodsThirty-seven contrast-enhanced, clinically indicated cardiac CTs performed on PCD CT were matched with 37 examinations acquired by EID CT. The patients were matched according to water-equivalent diameters. Quantitative evaluation of image quality comprised a region of interest (ROI)-based analysis, calculating image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratio. Differences of the attenuation variation of the paraspinal and the pectoral muscles were calculated to measure beam hardening artifacts. Volume CT dose index (CTDIvol) and dose length product (DLP) were documented, and the effective radiation dose was calculated for each patient. Statistical analysis comprised t-tests and Wilcoxon signed rank tests.ResultsThe mean age of the children on PCD CT was 794 ± 1016 days, similar to the mean age of 815 ± 957 days of the children on EID CT (p = 0.76). Moreover, age, height, weight, and body mass index (BMI) were also not significantly different between the two groups (p ≥ 0.32). Radiation exposure was significantly lower on PCD CT (CTDIvol 0.20 ± 0.12 mGy and DLP 4.06 ± 3.22 mGy*cm) versus EID CT (CTDIvol 0.37 ± 0.17 mGy, p < 0.001 and DLP 7.21 ± 4.67 mGy*cm, p < 0.001). No significant differences in SNR, CNR, or beam hardening artifacts could be observed. Qualitative image quality was also comparable for PCD CT versus EID CT.ConclusionsWith a reduction in radiation exposure exceeding 40% by using PCD CT, image quality remained stable compared to EID CT. Reducing radiation with PCD CT while preserving image quality might substantially advance cardiac imaging in children.Key PointsQuestionChildren are particularly sensitive to radiation exposure, highlighting the need for dose reduction.FindingsRadiation dosage can be significantly reduced while preserving image quality when using photon-counting detector (PCD) CT in pediatric patients with congenital heart disease.Clinical relevanceSince radiation exposure can be significantly reduced by PCD CT compared to energy-integrating detector (EID) CT, while image quality was comparable, PCD CT is advisable for children with congenital heart disease.Graphical

Photon-counting detector (PCD) CT allows for reduced intravenous iodinated contrast dosing with preserved or improved image quality across anatomical regions as compared to conventional energy-integrating detector (EID) CT in adults. However, there is limited evidence to support this in pediatric CT, particularly for pediatric chest CT. To compare image quality of photon-counting detector (PCD) chest CT with energy-integrating detector (EID) CT at varying iodinated contrast doses in pediatric patients. This retrospective observational study included 60 contrast-enhanced chest CT studies in pediatric patients. The cohort included three groups: 20 PCD CT scans with a 1.5mL/kg weight-based iodinated contrast dose, 20 EID CT scans with a 1.5mL/kg dose, and 20 EID CT scans with a 2.0mL/kg dose. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were assessed through region-of-interest measurement of Hounsfield units (HU) and standard deviation (SD). Assessed locations were the lung parenchyma, thoracic aorta, main pulmonary artery, left ventricle cavity, subcutaneous tissue, and pectoralis muscle. Blinded review by three pediatric radiologists assessed overall contrast enhancement, soft tissue delineation, and streak artifact from dense contrast using 5-point Likert scales (1 - excellent to 5 - non-diagnostic). Group comparisons were analyzed using Wilcoxon signed-rank, Chi-square, and Kruskal-Wallis tests. Twenty patients were included for each group (60 patients total). Compared to equivalent-contrast dose EID CT at 1.5mL/kg, PCD CT showed higher left ventricle cavity SNR (21.6 [IQR 16.3-25.1] vs 16.2 [IQR 12.3-19.3], P = 0.05) and CNR (16.0 [IQR 11.3-19.5] vs 10.3 [8.8-13.7] P = 0.05), and lower image noise in pectoralis muscle (P = 0.04) and subcutaneous fat (P < 0.01). Furthermore, objective image quality on PCD CT demonstrated improvements in lung parenchyma noise, SNR, and CNR, as well as subcutaneous fat SNR and CNR (all P < 0.01) compared with both equivalent (1.5mL/kg) and standard (2.0mL/kg) contrast dosing in EID CT. No significant differences between PCD CT and EID CT were observed with other objective measures of image quality. Subjective assessments favored PCD CT for overall contrast enhancement to EID CT at equivalent (1.5mL/kg) contrast dosing (median 1, IQR 1-1 vs median 2, IQR 1-5, P = 0.02) and soft tissue delineation compared with EID CT with higher (2.0mL/kg) contrast dosing (median 1, IQR 1-2 vs median 2, IQR 1-2, P = 0.05). Pediatric chest CT using photon-counting detector technology enables iodinated contrast dose reduction while preserving image quality compared with conventional EID CT at standard contrast doses.