Size-Specific Dose Estimates (SSDE) in Pediatric and Adult Body CT Examinations

Boone, John M.; Strauss, Keith J.; Cody, Dianna D.; McCollough, Cynthia H.; McNitt‐Gray, Michael F.; Toth, Thomas L.; Goske, Marilyn J.; Frush, Donald P.

doi:10.37206/143

Cited by 263 publications

(192 citation statements)

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“…Figure 3 shows that the UW linear fits of D E as a function of (AP + LAT)/2, LAT, and AP compare well to the fits in the AAPM Report 204. 8 ICRU92 were elliptical. The LAT dimensions over 400 mm from the AAPM Report 204 are the only data outside of our 95% confidence interval.…”

Section: A | Lat and Ap Comparisonmentioning

confidence: 97%

“…[3][4][5][6][7][8] A method that scales CTDIvol with a scaling factor that depends on patient size exists. The American Association of Physicists in Medicine (AAPM) Report 204 8 introduced this scaling factor, the normalized dose coefficient (NDC), and it is calculated based on patient size surrogates anterior-posterior (AP), lateral (LAT), and effective diameter (sqrt[AP*LAT]). However, these estimates of patient surrogates from CT axial images can only be performed after the CT scan is finished and images are reconstructed.…”

Section: Introductionmentioning

confidence: 99%

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Method of determining geometric patient size surrogates using localizer images in CT

Burton

2020

J Applied Clin Med Phys

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Purpose Size‐specific dose estimates (SSDE) requires accurate estimates of patient size surrogates. AAPM Report 204 shows that the SSDE is the product of CTDIvol and a scaling factor, the normalized dose coefficient (NDC) which depends on patient size surrogates for CT axial images. However, SSDE can be determined from CT localizer prior to CT scanning. AAPM Report 220 charges that a magnification correction is needed for geometric patient size‐surrogates. In this study, we demonstrate a novel “model‐based” magnification correction on patient data. Methods 573 patient scans obtained from a clinical CT system including 229 adult abdomen, 284 adult chest, 48 pediatric abdomen, and 12 pediatric chest exams. LAT and AP dimensions were extracted from CT localizers using a threshold extraction method (the ACR DIR). The model‐based magnification correction was applied to the AP and LAT dimensions extracted using the ACR DIR. NDC was calculated using the effective diameter for the ACR DIR only, the model‐based localizer‐based and axial‐based approaches. The LAT and AP dimensions were extracted from the “gold” standard CT axial scans. Outliers are defined as points outside the 95% confidence intervals and were analyzed. Results NDC estimates for the localizer‐based model‐based approach had an excellent correlation (R2 = 0.92) with the gold standard approach. The effective diameter for ACR DIR and model‐based approaches are 8.0% and 1.0% greater than the gold standard respectively. Outliers were determined to be primarily patient truncation, with arms down or with devices. ACR DIR size extraction method fails for bariatric patients where the threshold is too high and some of their anatomy was included in the CT couch, and small patients due to the CT couch being included in the size measurement. Conclusion The model‐based magnification method gives an accurate estimate of patient size surrogates extracted from CT localizers that are needed for calculating NDC to achieve accurate SSDE.

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Section: A | Lat and Ap Comparisonmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Method of determining geometric patient size surrogates using localizer images in CT

Burton

2020

J Applied Clin Med Phys

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“…The volumetric CT dose index (CTDIvol) and dose length product (DLP) were recorded by the scanner. The size-specific dose estimate (SSDE) was calculated by multiplying the CTDIvol by size-specific conversion factors: SSDE=CTDI 5 The effective dose (ED) was calculated by multiplying the DLP by size-specific conversion factors and age-dependent conversion factors: ED=DLP×conversion factor (f)×conversion factor (c). 6 The conversion factors (c in mSv/ mGy-cm) were 0.039 for patients less than 1-year old; 0.026, for 1-5 years old; 0.018, for 6-10 years old and 0.013, for 11-18 years old.…”

Section: Radiation Dosementioning

confidence: 99%

Application of low dose radiation and low concentration contrast media in enhanced CT scans in children with congenital heart disease

Liu

Song

et al. 2016

Int J Clin Pract

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“…1,2 Concerns about stochastic effects due to increased radiation dose from medical procedures have been a recent motivation to not only report radiation dose from CT but also to improve currently used metrics such as CTDI to patient size-specific dose estimates (SSDEs). [3][4][5][6][7][8] However, CTDI (Ref. 9) and SSDE do not represent organ dose, which is necessary for estimating individual risk from ionizing radiation.…”

Section: Introductionmentioning

confidence: 99%

“…Although these metrics can guide the improvement of our clinical practice, they should not be used for assessing the risk from diagnostic imaging procedures for individual patients. 8 It has been shown that the most appropriate metric for assessing this risk to specific subject is the radiation dose to individual organs. 3,[10][11][12][13][14] One feasible approach to estimating organ dose to patients undergoing CT examinations would be simulations using Monte Carlo radiation transport codes.…”

Section: Introductionmentioning

confidence: 99%