Size-specific dose estimate (SSDE) provides a simple method to calculate organ dose for pediatric CT examinations

Moore, Bria M.; Brady, Samuel L.; Mirro, Amy E.; Kaufman, Robert A.

doi:10.1118/1.4884227

Cited by 84 publications

(65 citation statements)

References 31 publications

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“…(4) and the correlation factors (CF organ SSDE ) for the thorax and abdominopelvic were adopted from the publication by Moore et al 25 A correlation factor for the brain (CF organ SSDE = 0.9 ± 0.1) was established based on the methodology described in Moore et al…”

Section: C Patient Examinationsmentioning

confidence: 99%

Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

Brady

Shulkin

2015

Medical Physics

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Section: C Patient Examinationsmentioning

confidence: 99%

Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

Brady

Shulkin

2015

Medical Physics

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“…A patient‐specific phantom represents a realistic model enabling accurate estimation of organ‐level dose; however, the segmentation of patient images is time consuming and not feasible for clinical routine applications. A potential alternative for person‐specific organ dose estimation is to use a library of computational models where habitus‐specific phantoms could serve as alternative models covering various anthropometric and anatomical characteristics of patients . Several habitus‐dependent phantom series have been developed to perform patient‐specific dose estimation by matching anthropometric characteristics of patients, such as gender, age, height, and body weight .…”

Section: Introductionmentioning

confidence: 99%

“…A potential alternative for person-specific organ dose estimation is to use a library of computational models where habitus-specific phantoms could serve as alternative models covering various anthropometric and anatomical characteristics of patients. 8 Several habitus-dependent phantom series have been developed to perform patient-specific dose estimation by matching anthropometric characteristics of patients, such as gender, age, height, and body weight. [9][10][11] Stepusin et al 12 suggested to match patient's data to a computational phantom from a predefined library using height and weight matching for patient-specific CT dosimetry.…”

Section: Introductionmentioning

confidence: 99%

Construction of patient‐specific computational models for organ dose estimation in radiological imaging

2019

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Purpose Diagnostic imaging procedures require optimization depending on the medical task at hand, the apparatus being used, and patient physical and anatomical characteristics. The assessment of the radiation dose and associated risks plays a key role in safety and quality management for radiation protection purposes. In this work, we aim at developing a methodology for personalized organ‐level dose assessment in x‐ray computed tomography (CT) imaging. Methods Regional voxel models representing reference patient‐specific computational phantoms were generated through image segmentation of CT images for four patients. The best‐fitting anthropomorphic phantoms were selected from a previously developed comprehensive phantom library according to patient's anthropometric parameters, then registered to the anatomical masks (skeleton, lung, and body contour) of patients to produce a patient‐specific whole‐body phantom. Well‐established image registration metrics including Jaccard's coefficients for each organ, organ mass, body perimeter, organ‐surface distance, and effective diameter are compared between the reference patient model, registered model, and anchor phantoms. A previously validated Monte Carlo code is utilized to calculate the absorbed dose in target organs along with the effective dose delivered to patients. The calculated absorbed doses from the reference patient models are then compared with the produced personalized model, anchor phantom, and those reported by commercial dose monitoring systems. Results The evaluated organ‐surface distance and body effective diameter metrics show a mean absolute difference between patient regional voxel models, serving as reference, and patient‐specific models around 4.4% and 4.5%, respectively. Organ‐level radiation doses of patient‐specific models are in good agreement with those of the corresponding patient regional voxel models with a mean absolute difference of 9.1%. The mean absolute difference of organ doses for the best‐fitting model extracted from the phantom library and Radimetrics™ commercial dose tracking software are 15.5% and 41.1%, respectively. Conclusion The results suggest that the proposed methodology improves the accuracy of organ‐level dose estimation in CT, especially for extreme cases [high body mass index (BMI) and large skeleton]. Patient‐specific radiation dose calculation and risk assessment can be performed using the proposed methodology for both monitoring of cumulative radiation exposure of patients and epidemiological studies. Further validation using a larger database is warranted.

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“…SSDE “…provides an estimate of the dose at the center of the scanned region (along z) in the patient” and is defined as the patient dose estimate that takes into account corrections based on patient size by AAPM Report 204 . Although SSDE has been shown to be a good substitute for organ dose in the context of abdominal scans, the work of AAPM Report 204 was limited only to body CT examinations.…”

Section: Introductionmentioning

confidence: 99%

Estimating a size‐specific dose for helical head CT examinations using Monte Carlo simulation methods

et al. 2018

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Purpose Size‐specific dose estimates (SSDE) conversion factors have been determined by AAPM Report 204 to adjust CTDIvol to account for patient size but were limited to body CT examinations. The purpose of this work was to determine conversion factors that could be used for an SSDE for helical, head CT examinations for patients of different sizes. Methods Validated Monte Carlo (MC) simulation methods were used to estimate dose to the center of the scan volume from a routine, helical head examination for a group of patient models representing a range of ages and sizes. Ten GSF/ICRP voxelized phantom models and five pediatric voxelized patient models created from CT image data were used in this study. CT scans were simulated using a Siemens multidetector row CT equivalent source model. Scan parameters were taken from the AAPM Routine Head protocols for a fixed tube current (FTC), helical protocol, and scan lengths were adapted to the anatomy of each patient model. MC simulations were performed using mesh tallies to produce voxelized dose distributions for the entire scan volume of each model. Three tally regions were investigated: (1) a small 0.6 cc volume at the center of the scan volume, (2) 0.8–1.0 cm axial slab at the center of the scan volume, and (3) the entire scan volume. Mean dose to brain parenchyma for all three regions was calculated. Mean bone dose and a mass‐weighted average dose, consisting of brain parenchyma and bone, were also calculated for the slab in the central plane and the entire scan volume. All dose measures were then normalized by CTDIvol for the 16 cm phantom (CTDIvol,16). Conversion factors were determined by calculating the relationship between normalized doses and water equivalent diameter (Dw). Results CTDIvol,16‐normalized mean brain parenchyma dose values within the 0.6 cc volume, 0.8–1.0 cm central axial slab, and the entire scan volume, when parameterized by Dw, had an exponential relationship with a coefficient of determination (R2) of 0.86, 0.84, and 0.88, respectively. There was no statistically significant difference between the conversion factors resulting from these three different tally regions. Exponential relationships between CTDIvol,16‐normalized mean bone doses had R2 values of 0.83 and 0.87 for the central slab and for the entire scan volume, respectively. CTDIvol,16‐normalized mass‐weighted average doses had R2 values of 0.39 and 0.51 for the central slab and for the entire scan volume, respectively. Conclusions Conversion factors that describe the exponential relationship between CTDIvol,16‐normalized mean brain dose and a size metric (Dw) for helical head CT examinations have been reported for two different interpretations of the center of the scan volume. These dose descriptors have been extended to describe the dose to bone in the center of the scan volume as well as a mass‐weighted average dose to brain and bone. These may be used, when combined with other efforts, to develop an SSDE dose coefficients for routine, helical head CT examinations.

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Size-specific dose estimate (SSDE) provides a simple method to calculate organ dose for pediatric CT examinations

Cited by 84 publications

References 31 publications

Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

Ultralow dose computed tomography attenuation correction for pediatric PET CT using adaptive statistical iterative reconstruction

Construction of patient‐specific computational models for organ dose estimation in radiological imaging

Estimating a size‐specific dose for helical head CT examinations using Monte Carlo simulation methods

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