A Toolkit for Pediatric CT Dose Reduction in Community Hospitals.
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ABSTRACT:
SUBMITTER: Armao D
PROVIDER: S-EPMC5097688 | biostudies-literature | 2016 Nov
REPOSITORIES: biostudies-literature
Publications
A Toolkit for Pediatric CT Dose Reduction in Community Hospitals.
Armao Diane D Hartman Terry T Shea Christopher M CM Sams Cassandra C Ivanovic Marija M Fordham Lynn Ansley LA Smith J Keith JK
Journal of the American College of Radiology : JACR 20160609 11
Pediatric CT radiation dose optimization is a challenging process for pediatric-focused facilities and community hospitals alike. Ongoing experience and trial-and-error approaches to dose reduction in the large academic hospital setting may position these centers to help community hospitals that strive for CT quality improvement. We describe our hands-on approach in a pilot project to create a partnership between an academic medical center and a community hospital to develop a toolkit for implem ...[more]
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Project description:To determine a comprehensive method for the implementation of adaptive statistical iterative reconstruction (ASIR) for maximal radiation dose reduction in pediatric computed tomography (CT) without changing the magnitude of noise in the reconstructed image or the contrast-to-noise ratio (CNR) in the patient.The institutional review board waived the need to obtain informed consent for this HIPAA-compliant quality analysis. Chest and abdominopelvic CT images obtained before ASIR implementation (183 patient examinations; mean patient age, 8.8 years ± 6.2 [standard deviation]; range, 1 month to 27 years) were analyzed for image noise and CNR. These measurements were used in conjunction with noise models derived from anthropomorphic phantoms to establish new beam current-modulated CT parameters to implement 40% ASIR at 120 and 100 kVp without changing noise texture or magnitude. Image noise was assessed in images obtained after ASIR implementation (492 patient examinations; mean patient age, 7.6 years ± 5.4; range, 2 months to 28 years) the same way it was assessed in the pre-ASIR analysis. Dose reduction was determined by comparing size-specific dose estimates in the pre- and post-ASIR patient cohorts. Data were analyzed with paired t tests.With 40% ASIR implementation, the average relative dose reduction for chest CT was 39% (2.7/4.4 mGy), with a maximum reduction of 72% (5.3/18.8 mGy). The average relative dose reduction for abdominopelvic CT was 29% (4.8/6.8 mGy), with a maximum reduction of 64% (7.6/20.9 mGy). Beam current modulation was unnecessary for patients weighing 40 kg or less. The difference between 0% and 40% ASIR noise magnitude was less than 1 HU, with statistically nonsignificant increases in patient CNR at 100 kVp of 8% (15.3/14.2; P = .41) for chest CT and 13% (7.8/6.8; P = .40) for abdominopelvic CT.Radiation dose reduction at pediatric CT was achieved when 40% ASIR was implemented as a dose reduction tool only; no net change to the magnitude of noise in the reconstructed image or the patient CNR occurred.
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Project description:Current methods for organ and effective dose estimations in pediatric CT are largely patient generic. Physical phantoms and computer models have only been developed for standard/limited patient sizes at discrete ages (e.g., 0, 1, 5, 10, 15 years old) and do not reflect the variability of patient anatomy and body habitus within the same size/age group. In this investigation, full-body computer models of seven pediatric patients in the same size/protocol group (weight: 11.9-18.2 kg) were created based on the patients' actual multi-detector array CT (MDCT) data. Organs and structures in the scan coverage were individually segmented. Other organs and structures were created by morphing existing adult models (developed from visible human data) to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. Organ and effective dose of these patients from a chest MDCT scan protocol (64 slice LightSpeed VCT scanner, 120 kVp, 70 or 75 mA, 0.4 s gantry rotation period, pitch of 1.375, 20 mm beam collimation, and small body scan field-of-view) was calculated using a Monte Carlo program previously developed and validated to simulate radiation transport in the same CT system. The seven patients had normalized effective dose of 3.7-5.3 mSv/100 mAs (coefficient of variation: 10.8%). Normalized lung dose and heart dose were 10.4-12.6 mGy/100 mAs and 11.2-13.3 mGy/100 mAs, respectively. Organ dose variations across the patients were generally small for large organs in the scan coverage (<7%), but large for small organs in the scan coverage (9%-18%) and for partially or indirectly exposed organs (11%-77%). Normalized effective dose correlated weakly with body weight (correlation coefficient: r=-0.80). Normalized lung dose and heart dose correlated strongly with mid-chest equivalent diameter (lung: r=-0.99, heart: r=-0.93); these strong correlation relationships can be used to estimate patient-specific organ dose for any other patient in the same size/protocol group who undergoes the chest scan. In summary, this work reported the first assessment of dose variations across pediatric CT patients in the same size/protocol group due to the variability of patient anatomy and body habitus and provided a previously unavailable method for patient-specific organ dose estimation, which will help in assessing patient risk and optimizing dose reduction strategies, including the development of scan protocols.
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Project description:ObjectiveFew studies have explored the clinical feasibility of using deep-learning reconstruction to reduce the radiation dose of CT. We aimed to compare the image quality and lung nodule detectability between chest CT using a quarter of the low dose (QLD) reconstructed with vendor-agnostic deep-learning image reconstruction (DLIR) and conventional low-dose (LD) CT reconstructed with iterative reconstruction (IR).Materials and methodsWe retrospectively collected 100 patients (median age, 61 years [IQR, 53-70 years]) who received LDCT using a dual-source scanner, where total radiation was split into a 1:3 ratio. QLD CT was generated using a quarter dose and reconstructed with DLIR (QLD-DLIR), while LDCT images were generated using a full dose and reconstructed with IR (LD-IR). Three thoracic radiologists reviewed subjective noise, spatial resolution, and overall image quality, and image noise was measured in five areas. The radiologists were also asked to detect all Lung-RADS category 3 or 4 nodules, and their performance was evaluated using area under the jackknife free-response receiver operating characteristic curve (AUFROC).ResultsThe median effective dose was 0.16 (IQR, 0.14-0.18) mSv for QLD CT and 0.65 (IQR, 0.57-0.71) mSv for LDCT. The radiologists' evaluations showed no significant differences in subjective noise (QLD-DLIR vs. LD-IR, lung-window setting; 3.23 ± 0.19 vs. 3.27 ± 0.22; P = .11), spatial resolution (3.14 ± 0.28 vs. 3.16 ± 0.27; P = .12), and overall image quality (3.14 ± 0.21 vs. 3.17 ± 0.17; P = .15). QLD-DLIR demonstrated lower measured noise than LD-IR in most areas (P < .001 for all). No significant difference was found between QLD-DLIR and LD-IR for the sensitivity (76.4% vs. 72.2%; P = .35) or the AUFROCs (0.77 vs. 0.78; P = .68) in detecting Lung-RADS category 3 or 4 nodules. Under a noninferiority limit of -0.1, QLD-DLIR showed noninferior detection performance (95% CI for AUFROC difference, -0.04 to 0.06).ConclusionQLD-DLIR images showed comparable image quality and noninferior nodule detectability relative to LD-IR images.
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Project description:ObjectivesTo examine hospital-level factors associated with the use of a dedicated pediatric dose-reduction protocol and protective shielding for head CT in a national sample of hospitals.MethodsA mixed-mode (online and paper) survey was administered to a stratified random sample of US community hospitals (N = 751). Respondents provided information on pediatric head CT scanning practices, including use of a dose-reduction protocol. Modified Poisson regression analyses describe the relative risk (RR) of not reporting the use of a pediatric dose-reduction protocol or protective shielding; multivariable analyses adjust for census region, trauma level, children's hospital status, and bed size.ResultsOf hospitals that were contacted, 38 were ineligible (no CT scanner, hospital closed, do not scan infants), 1 refused, and 253 responded (35.5% response rate). Across all hospitals, 92.6% reported using a pediatric dose-reduction protocol. Modified Poisson regression showed that small hospitals (0-50 beds) were 20% less likely to report using a protocol than large hospitals (>150 beds) (RR: 0.80, 95% confidence interval [CI]: 0.65-0.99; adjusted for covariates). Teaching hospitals were more likely to report using a protocol (RR: 1.10, 95% CI: 1.02-1.19; adjusted for covariates). After adjusting for covariates, children's hospitals were significantly less likely to report using protective shielding than nonchildren's hospitals (RR: 0.64, 95% CI: 0.56-0.73), though this may be due to more advanced scanner type.ConclusionResults from this study provide guidance for tailored educational campaigns and quality improvement interventions to increase the adoption of pediatric dose-reduction efforts.
| S-EPMC4082793 | biostudies-literature
Project description:To estimate patient-specific radiation dose and cancer risk for pediatric chest computed tomography (CT) and to evaluate factors affecting dose and risk, including patient size, patient age, and scanning parameters.The institutional review board approved this study and waived informed consent. This study was HIPAA compliant. The study included 30 patients (0-16 years old), for whom full-body computer models were recently created from clinical CT data. A validated Monte Carlo program was used to estimate organ dose from eight chest protocols, representing clinically relevant combinations of bow tie filter, collimation, pitch, and tube potential. Organ dose was used to calculate effective dose and risk index (an index of total cancer incidence risk). The dose and risk estimates before and after normalization by volume-weighted CT dose index (CTDI(vol)) or dose-length product (DLP) were correlated with patient size and age. The effect of each scanning parameter was studied.Organ dose normalized by tube current-time product or CTDI(vol) decreased exponentially with increasing average chest diameter. Effective dose normalized by tube current-time product or DLP decreased exponentially with increasing chest diameter. Chest diameter was a stronger predictor of dose than weight and total scan length. Risk index normalized by tube current-time product or DLP decreased exponentially with both chest diameter and age. When normalized by DLP, effective dose and risk index were independent of collimation, pitch, and tube potential (<10% variation).The correlations of dose and risk with patient size and age can be used to estimate patient-specific dose and risk. They can further guide the design and optimization of pediatric chest CT protocols.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101900/-/DC1.
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Project description:Phase-contrast X-ray imaging can improve the visibility of weakly absorbing objects (e.g. soft tissues) by an order of magnitude or more compared to conventional radiographs. Combining phase retrieval with computed tomography (CT) can increase the signal-to-noise ratio (SNR) by up to two orders of magnitude over conventional CT at the same radiation dose, without loss of image quality. Our experiments reveal that as the radiation dose decreases, the relative improvement in SNR increases. We show that this enhancement can be traded for a reduction in dose greater than the square of the gain in SNR. Upon reducing the dose 300 fold, the phase-retrieved SNR was still up to 9.6?±?0.2 times larger than the absorption contrast data with spatial resolution in the tens of microns. We show that this theoretically reveals the potential for dose reduction factors in the tens of thousands without loss in image quality, which would have a profound impact on medical and industrial imaging applications.
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Project description:BackgroundComputed tomography (CT) emphysema quantification is affected by both radiation dose (i.e. image noise) and reconstruction technique. At reduced dose, filtered back projection (FBP) results in an overestimation of the amount of emphysema due to higher noise levels, while the use of iterative reconstruction (IR) can result in an underestimation due to reduced noise. The objective of this study was to determine the influence of dose reduction and hybrid IR (HIR) or model-based IR (MIR) on CT emphysema quantification.MethodsTwenty-two patients underwent inspiratory chest CT scan at routine radiation dose and at 45%, 60% and 75% reduced radiation dose. Acquisitions were reconstructed with FBP, HIR and MIR. Emphysema was quantified using the 15th percentile of the attenuation curve and the percentage of voxels below -950 HU. To determine whether the use of a different percentile or HU threshold is more accurate at reduced dose levels and with IR, additional measurements were performed using different percentiles and HU thresholds to determine the optimal combination.ResultsDose reduction resulted in a significant overestimation of emphysema, while HIR and MIR resulted in an underestimation. Lower HU thresholds with FBP at reduced dose and higher HU thresholds with HIR and MIR resulted in emphysema percentages comparable to the reference. The 15th percentile quantification method showed similar results as the HU threshold method.ConclusionsThis within-patients study showed that CT emphysema quantification is significantly affected by dose reduction and IR. This can potentially be solved by adapting commonly used thresholds.
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Project description:Background and purposeThe American College of Radiology-American Society of Neuroradiology-Society for Pediatric Radiology Practice Parameter for a neck CT suggests that coverage should be from the sella to the aortic arch. It also recommends using CT scans judiciously to achieve the clinical objective. Our purpose was to analyze the potential dose reduction by decreasing the scan length of a neck CT and to assess for any clinically relevant information that might be missed from this modified approach.Materials and methodsThis retrospective study included 126 children who underwent a neck CT between August 1, 2013, and September 30, 2014. Alteration of the scan length for the modified CT was suggested on the topographic image on the basis of the indication of the study, with the reader blinded to the images and the report. The CT dose index volume of the original scan was multiplied by the new scan length to calculate the dose-length product of the modified study. The effective dose was calculated for the original and modified studies by using age-based conversion factors from the American Association of Physicists in Medicine Report No. 96.ResultsDecreasing the scan length resulted in an average estimated dose reduction of 47%. The average reduction in scan length was 10.4 cm, decreasing the overall coverage by 48%. The change in scan length did not result in any missed findings that altered management. Of the 27 abscesses in this study, none extended to the mediastinum. All of the lesions in question were completely covered.ConclusionsDecreasing the scan length of a neck CT according to the indication provides a significant savings in radiation dose, while not altering diagnostic ability or management.
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Project description:BackgroundAlthough the majority of children are hospitalized in nonchildren's hospitals, little is known about the quality and safety of pediatric care in community hospitals.ObjectiveThe aim of this study was to conduct a scoping review and synthesize literature on the quality and safety of pediatric inpatient care in United States community hospitals.MethodsWe performed a systematic literature search in October 2016 to identify pediatric studies that reported on safety, effectiveness, efficiency, timeliness, patient-centeredness, or equity set in general, nonuniversity, or nonchildren's hospitals. We extracted data on study design, patient descriptors, and quality outcomes and assessed the risk of bias using modified Newcastle-Ottawa Scales.ResultsA total of 44 articles met the inclusion criteria. Study designs, patient populations, and quality outcome measures were heterogeneous; only three clinical domains, (1) perinatal regionalization, (2) telemedicine, and (3) imaging radiation, were explored in multiple studies with consistent directionality of results. A total of 30 studies were observational, and 22 studies compared community hospital quality outcomes with other hospital types. The remaining 14 studies reported testing of interventions; 12 showed improved quality of care postintervention. All studies reported an outcome addressing safety, effectiveness, or efficiency, whereas timeliness, patient-centeredness, and equity were infrequently addressed. Risk of bias was moderate or high for 72% of studies.ConclusionsLiterature on the inpatient care of children in community hospitals is limited, making it difficult to evaluate healthcare quality. Measures of timeliness, patient-centeredness, and equity are underrepresented. The field would benefit from more multicenter collaborations to facilitate the application of robust study designs and to enable a systematic assessment of individual interventions and community hospital quality outcomes.
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