Size-specific Dose Estimates for Adult Patients at CT of the Torso

Christner, Jodie A.; Braun, Natalie N.; Jacobsen, Megan C.; Carter, Rickey E.; Kofler, James M.; McCollough, Cynthia H.

doi:10.1148/radiol.12112365

Cited by 164 publications

(109 citation statements)

References 16 publications

(27 reference statements)

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“…The first limitation is that the length of phantom is too short for measuring scattered radiation 16 , 17 , 18 , 19 . The second limitation is that the diameter of the phantom does not represent the variation in diameters among patients 20 , 21 , 22 . For a given CT technique, the patient dose decreases as patient size increases, due to the increased attenuation of the incident X‐ray beam.…”

Section: Introductionmentioning

confidence: 99%

Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220

Anam

Haryanto

Widita

et al. 2016

J Applied Clin Med Phys

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The purpose of this study is to accurately and effectively automate the calculation of the water‐equivalent diameter (normalDnormalW) from 3D CT images for estimating the size‐specific dose. normalDnormalW is the metric that characterizes the patient size and attenuation. In this study, normalDnormalW was calculated for standard CTDI phantoms and patient images. Two types of phantom were used, one representing the head with a diameter of 16 cm and the other representing the body with a diameter of 32 cm. Images of 63 patients were also taken, 32 who had undergone a CT head examination and 31 who had undergone a CT thorax examination. There are three main parts to our algorithm for automated normalDnormalW calculation. The first part is to read 3D images and convert the CT data into Hounsfield units (HU). The second part is to find the contour of the phantoms or patients automatically. And the third part is to automate the calculation of normalDnormalW based on the automated contouring for every slice (normalDW,all). The results of this study show that the automated calculation of normalDnormalW and the manual calculation are in good agreement for phantoms and patients. The differences between the automated calculation of normalDnormalW and the manual calculation are less than 0.5%. The results of this study also show that the estimating of normalDW,all using normalDW,n=1 (central slice along longitudinal axis) produces percentage differences of −0.92%±3.37% and 6.75%±1.92%, and estimating normalDW,all using normalDW,n=9 produces percentage differences of 0.23%±0.16% and 0.87%±0.36%, for thorax and head examinations, respectively. From this study, the percentage differences between normalized size‐specific dose estimate for every slice (nSSDEall) and nSSDEnormaln=1 are 0.74%±2.82% and −4.35%±1.18% for thorax and head examinations, respectively; between nSSDEall and nSSDEnormaln=9 are 0.00%±0.46% and −0.60%±0.24% for thorax and head examinations, respectively.PACS number(s): 87.57.Q‐, 87.57.uq‐

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Section: Introductionmentioning

confidence: 99%

Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220

Anam

Haryanto

Widita

et al. 2016

J Applied Clin Med Phys

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“…For example, CTDI vol ranged from 4 to 19 mGy in paediatric necks equivalent to water cylinder diameters from 10 to 12 cm. The variability of CTDI vol for necks of equivalent size in CT studies performed with the AEC is due to variation in the patient's body habitus and selected scan range [19,20]. In fact, CTDI vol is expected to differ for patients of the same size if there are differences in neck thickness and density.…”

Section: Discussionmentioning

confidence: 99%

Thyroid doses and risk to paediatric patients undergoing neck CT examinations

et al. 2015

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“…The size-specific dose estimate (SSDE) of the baseline and follow-up examinations was calculated based on the individual effective patient diameter, as measured from the axial CT images (Christner et al 2013). …”

Section: Ct Protocolmentioning

confidence: 99%

Locally advanced gastric cancer: total iodine uptake to predict the response of primary lesion to neoadjuvant chemotherapy

Gao

Zhang

Yuan

et al. 2018

J Cancer Res Clin Oncol

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Purpose Pathologic response to neoadjuvant chemotherapy is a prognostic factor in many cancer types. However, the existing evaluative criteria are deficient. We sought to prospectively evaluate the total iodine uptake derived from dual-energy computed tomography (DECT) in predicting treatment efficacy and progression-free survival (PFS) time in gastric cancer after neoadjuvant chemotherapy. Methods From October 2012 to December 2015, 44 patients with locally advanced gastric cancer were examined with DECT 1 week before and three cycles after neoadjuvant chemotherapy. The percentage changes in tumor area (%ΔS), diameter (%ΔD), and density (%ΔHU) were calculated to evaluate the WHO, RESCIST, and Choi criteria. The percentage changes in tumor volume (%ΔV) and total iodine uptake of portal phase (%ΔTIU-p) were also calculated to determine cut-off values by ROC curves. The correlation between the different criteria and histopathologic tumor regression grade (Becker score) or PFS were statistically analyzed. Results Forty-four patients were divided into responders and non-responders according to 43.34% volume reduction (P = 0.002) and 63.87% (P = 0.002) TIU-p reduction, respectively. The %ΔTIU-p showed strong (r = 0.602, P = 0.000) and %ΔV showed moderate (r = 0.416, P = 0.005), while the WHO (r = 0.075, P = 0.627), RECIST (r = 0.270, P = 0.077) and Choi criteria (r = 0.238, P = 0.120) showed no correlation with the Becker score. The differences in PFS time between the responder and non-responder groups were significant according to %ΔTIU-p and Choi criteria (P = 0.001 and P = 0.013, respectively). Conclusions The TIU-p can help predict pathological regression in advanced gastric cancer patients after neoadjuvant chemotherapy. In addition, the %ΔTIU-p could be one of the potentially valuable predictive parameters of the PFS time.

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Size-specific Dose Estimates for Adult Patients at CT of the Torso

Abstract: For the evaluated automatic exposure control system,CTDI(vol) (scanner output) increased linearly with patient size; however, patient dose (as indicated by SSDE) was independent of size.

Cited by 164 publications

References 16 publications

Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220

Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220

Thyroid doses and risk to paediatric patients undergoing neck CT examinations

Locally advanced gastric cancer: total iodine uptake to predict the response of primary lesion to neoadjuvant chemotherapy

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Size-specific Dose Estimates for Adult Patients at CT of the Torso

Abstract: For the evaluated automatic exposure control system,CTDI(vol) (scanner output) increased linearly with patient size; however, patient dose (as indicated by SSDE) was independent of size.

Cited by 164 publications

References 16 publications

Automated Calculation of Water‐equivalent Diameter (DW) Based on AAPM Task Group 220

Automated Calculation of Water‐equivalent Diameter (DW) Based on AAPM Task Group 220

Thyroid doses and risk to paediatric patients undergoing neck CT examinations

Locally advanced gastric cancer: total iodine uptake to predict the response of primary lesion to neoadjuvant chemotherapy

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Product

Resources

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Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220

Automated Calculation of Water‐equivalent Diameter (D_W) Based on AAPM Task Group 220