Radiation Doses in Consecutive CT Examinations from Five University of California Medical Centers

Smith‐Bindman, Rebecca; Moghadassi, Michelle; Wilson, Nicole; Nelson, Thomas R.; Boone, John M.; Cagnon, Christopher H.; Gould, Robert G.; Hall, D.; Krishnam, Mayil S.; Lamba, Ramit; McNitt-Gray, Michael F.; Seibert, J. Anthony; Miglioretti, Diana L.

doi:10.1148/radiol.2015142728

Cited by 105 publications

(87 citation statements)

References 20 publications

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“…A recent study conducted by the University of California Dose Optimization and Standardization Endeavor (UC Dose) summarizing CT doses across 12 University of California medical centers found that head scans comprised 16% of all adult CT examinations . The same study also found that the most frequent area imaged in pediatric patients was the head, accounting for 33% of the total procedures administered . The fact that radiation exposure from head CT examinations is a large contributor to the total medical radiation exposures underscores the need for accurate patient dose assessments from head CT procedures, particularly for younger patients.…”

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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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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“…A group has also developed automated alerts for high-dose computed tomography (CT) exams based on how they compare to institutional average [18]. Recent experience in San Francisco medical centers is also now available for more general comparisons [19].…”

Section: Introductionmentioning

confidence: 99%

Open-Source Radiation Exposure Extraction Engine (RE3) with Patient-Specific Outlier Detection

et al. 2015

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We present an open-source, picture archiving and communication system (PACS)-integrated radiation exposure extraction engine (RE3) that provides study-, series-, and slice-specific data for automated monitoring of computed tomography (CT) radiation exposure. RE3 was built using opensource components and seamlessly integrates with the PACS. RE3 calculations of dose length product (DLP) from the Digital imaging and communications in medicine (DICOM) headers showed high agreement (R 2 =0.99) with the vendor dose pages. For study-specific outlier detection, RE3 constructs robust, automatically updating multivariable regression models to predict DLP in the context of patient gender and age, scan length, waterequivalent diameter (D w ), and scanned body volume (SBV). As proof of concept, the model was trained on 811 CT chest, abdomen + pelvis (CAP) exams and 29 outliers were detected. The continuous variables used in the outlier detection model were scan length (R 2 =0.45), D w (R 2 =0.70), SBV (R 2 =0.80), and age (R 2 =0.01). The categorical variables were gender (male average 1182.7 ±26.3 and female 1047.1±26.9 mGy cm) and pediatric status (pediatric average 710.7±73.6 mGy cm and adult 1134.5±19.3 mGy cm).

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“…Therapy related myeloid neoplasm, the development of either Myelodysplastic Syndrome (MDS) or Acute Myeloid Leukemia (AML), following exposure to therapeutic radiotherapy treatment, is well described and has a poor prognosis 4 . The impact of low dose (ie: less than 100mSv) radiation exposure, such as that conceivable from repeated CT imaging 5 , on the risk of subsequently developing acute leukemia was however less clear. in this issue of Lancet Haematology the work from Little and colleagues 6 convincingly suggests, using data from nine cohorts totaling over a quarter of a million children (including 137 cases of acute leukemia and MDS), that even low dose radiation exposure is associated with low, but quantifiable, increased risk of acute leukemia.…”

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confidence: 99%

“…As the authors state; this work re-enforces rather than challenges existing radiation protection guidelines. It may however stimulate reflection and allow conversations to ensure local radiology facilities are practicing according to best principles 2,3 to consistently limit radiation doses used for essential tests to the lowest possible level while also reducing variation by benchmarking to reference standards 5 . Our feeling is that minimizing radiation exposure, particularly in children, is prudent while also recognizing that the benefit for CT imaging for a strong medical indication outweighs risk 10 .…”

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confidence: 99%

Leukaemia risk associated with low-dose radiation

Hourigan

Savani

2018

The Lancet Haematology

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Radiation Doses in Consecutive CT Examinations from Five University of California Medical Centers

Cited by 105 publications

References 20 publications

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

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

Open-Source Radiation Exposure Extraction Engine (RE3) with Patient-Specific Outlier Detection

Leukaemia risk associated with low-dose radiation

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