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B. Alikhani, Tobias Getzin, Till Kaireit, K. Ringe, L. Jamali, F. Wacker, T. Werncke, H. Raatschen (2018)
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D. Brenner (2006)
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SU-E-I-28: Introduction and Investigation of Effective Diameter Ratios as a New Patient Size Metric for Use in CTMedical Physics, 42
Background: The size-specific dose estimate (SSDE) is a dose-related metrics that incorporates patient size into its calculation. It is usually derived from the volume computed tomography dose index (CTDI ) by applying a vol conversion factor determined from manually measured anteroposterior and lateral skin-to-skin patient diameters at the midslice level on computed tomography (CT) localiser images, an awkward, time-consuming, and not highly reproducible technique. The objective of this study was to evaluate the potential for the use of body mass index (BMI) as a size-related metrics alternative to the midslice effective diameter (D )toobtainasize-specificdose(SSDE)inabdominalCT. Methods: In this retrospective study of patients who underwent abdominal CT for the investigation of inflammatory bowel disease, the D was measuredonthe midslice levelonCT-localiser images of each patient. This was correlated with patient BMI and the linear regression equation relating the quantities was calculated. The ratio between the internal and the external abdominal diameters (D ) was also measured to assess correlation RATIO with radiation dose. Pearson correlation analysis and linear regression models were used. Results: There was good correlation between D and patient BMI (r = 0.88). An equation allowing calculation of D from BMI was calculated by linear regression analysis as follows: D =0.76 (BMI) + 9.4. A weak correlation E E between radiation dose and D was demonstrated (r = 0.45). RATIO Conclusions: Patient BMI can be used to accurately estimate D , obviating the need to measure anteroposterior and lateral diameters in order to calculate a SSDE for abdominal CT. Keywords: Abdomen, Body mass index, Tomography (x-ray, computed), Radiation dosage Key points the ever-increasing CT use and general concerns about the risks associated with radiation exposure from med- A strong correlation between BMI and D was found ical imaging. This has precipitated the increased use of BMI can be used to estimate patient D dose monitoring systems in clinical practice. Calculating patient BMI can facilitate individualised Current CT scanner radiation dose output following patient radiation dose estimation in abdominal CT patient imaging is displayed in the CT dose report in terms of volume CT dose index (CTDI ) and dose vol length product (DLP), standardised measurements de- Background duced from homogenous phantoms under normalised The individual patient radiation dose from computed conditions [1, 2]. These parameters do not provide a dir- tomography (CT) is notoriously difficult to estimate. ect measure of the individualised patient radiation dose, There is a growing interest in this topic, however, due to a variable that is dependent on patient size. The size-specific dose estimate (SSDE) is a dose-related * Correspondence: richykav@gmail.com metrics that incorporates patient size into its calculation. Department of Radiology, Cork University Hospital, Wilton, Cork, Ireland Department of Radiology, University College Cork, Cork, Ireland This metric has been advocated for the reporting of Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. O’Neill et al. European Radiology Experimental (2018) 2:38 Page 2 of 8 patient radiation dose in CT by the American Association phase; 1.5 L of positive oral contrast (2% Gastrografin, of Physicists in Medicine (AAPM) task group 204 and has Bracco Diagnostics Inc., Princeton, NJ, USA); tube voltage increasingly been applied and accepted [3, 4]. The SSDE is of 120 kVp; automated tube current modulation resulting derived from the CTDI by applying a conversion factor in a variable current with a minimum of 50 mA and a vol determined from manually measured anteroposterior and maximum of 350 mA; gantry rotation time of 0.8 s; noise lateral skin-to-skin patient diameters at the midslice level index 38. All CT images were acquired using a single on CT-localiser images [3]. On a practical level this tech- 64-slice multi-detector row CT scanner (Lightspeed nique can be awkward and time-consuming, and open to VCT-XTe, GE Healthcare, General Electric Medical Sys- interobserver measurement variability. tems, Waukesha, WI, USA). The DLP and CTDI values, vol The objective of this study was to evaluate the poten- as well as the corresponding phantom size, were recorded tial for using body mass index (BMI) as an alternative from each CT dose report. CTDI and DLP tolerances vol size metrics, in lieu of measured body diameters, to esti- were verified using a standard 32-cm Perspex phantom, a mate patient effective diameter (D ). Thus, estimation of 10-cm ionisation chamber with a Victoreen NERO mAx SSDE at the time of CT scanning would be more unit (Fluke Biomedical, Solon, OH, USA). user-friendly, contributing positively to patient radiation The SSDEs were calculated by multiplying the CTDI vol dose optimisation. of each patient by conversion factors corresponding to the effective patient diameters in the AAPM reference tables Methods [3]. The imaging performance and assessment from CT Subjects patient dosimetry calculator (ImPACT version 0.99x, This study was performed retrospectively on CT data ac- London, UK) was used to calculate the effective dose. quired as part of a clinical trial protocol investigating the use of CT in inflammatory bowel disease (ClinicalTrials. BMI measurement gov Identifier: NCT 01244386) [5] with approval from Each patient had weight and height measurements per- the institution Clinical Research Ethics Committee. Fifty formed and their BMI calculated immediately prior to adult patients were included in this study and, as part of CT scan using a dedicated calibrated measuring device this trial protocol, all patients signed informed consent. (electronic measuring station Model 763, Seca Medical, Hamburg, Germany). BMI data were used to subdivide CT scan protocol patient groups, where underweight referred to BMI < All patients underwent a CT scan of the abdomen and 18.5 kg/m , normal weight referred to 18.5 ≤ BMI < 2 2 pelvis with a standardised protocol using the following 25 kg/m , overweight referred to 25 ≤ BMI < 30 kg/m parameters: scan range encompassing the lung bases to and obese referred to BMI ≥ 30 kg/m . the pubic symphysis; 0.625-mm slice acquisition thickness; intravenously administered contrast (Iohexol, Omnipaque Body diameter measurements 300, General Electric Healthcare, Waukesha, WI, USA) Images were reviewed on a picture-archiving and com- delivered at 2.5 mL/s and imaged in the portal venous munication system (PACS) workstation (Impax 6.3.1, Fig. 1 Measurement of lateral (D )(a) anteroposterior (D )(b) skin-to-skin patient diameters at the midslice level on CT-localiser images. LAT AP Measurement of the inner lateral and anteroposterior diameters on the axial midslice CT image excluding the subcutaneous adipose tissue (c) to allow calculation of the effect inner diameter (D ) and the effective diameter ratio (D ) IN RATIO O’Neill et al. European Radiology Experimental (2018) 2:38 Page 3 of 8 Table 1 Summary of mean values for computed tomography dose metrics, overall and stratified for body mass index (BMI) 2 2 All (n = 50) BMI < 25 kg/m (n = 32) BMI ≥ 25 kg/m (n = 18) p-value CTDI (mGy) 6.26 ± 3.83 4.33 ± 0.83 9.68 ± 4.65 0.000 vol DLP (mGy.cm) 299.42 ± 196.06 202.36 ± 41.27 471.96 ± 241.73 0.000 SSDE (mGy) 7.81 ± 3.08 6.22 ± 0.75 10.64 ± 3.61 0.000 Effective dose (mSv) 4.77 ± 3.23 3.18 ± 0.62 7.59 ± 1.64 0.000 CTDI volume-computed tomography dose index, DLP dose length product, SSDE size-specific dose estimate, BMI Body mass index vol Data as means ± standard deviations of the mean Value shows a statistically significant difference with a two-tailed p-value of less than 0.05, when the radiation doses of each protocol are compared with one another AGFA Healthcare, Morstel, Belgium) in a DICOM format. out all measurements. A fixed window level and setting As per AAPM Report 204 guidelines, body diameters were was used for each individual study. measured at the midslice level (median image of the cra- Maximum skin-to-skin anteroposterior diameter (D ) AP niocaudal scanning length) on the CT-localiser images be- and lateral diameter (D ) were measured in centi- LAT cause, for larger patients, maximum skin-to-skin distance metres on lateral and anteroposterior localiser images, is often not included on transverse CT images [3, 6]. respectively. D is defined as the anteroposterior AP Diameter measurements were performed manually with skin-to-skin diameter on the lateral localiser at the the electronic callipers available on the PACS using a win- midslice level (Fig. 1a)while D is defined as the LAT dow width of 350 Hounsfield Units (HU) and window lateral skin-to-skin diameter on the anteroposterior level of 50 HU. From personal experience at our institu- localiser image at the midslice level (Fig. 1b). The D tion, analysis of interoperator variability for PACS-based is defined as the diameter of the circle with area anthropometric measurements shows no statistically sig- equivalent to the cross-sectional area of the patient at nificant differences. Therefore, a single investigator carried the particular z-axis level (i.e. the midslice level) and Fig. 2 Graphs show the relationship of body mass index (BMI) to anteroposterior diameter (D )(a), lateral diameter (D )(b), effective diameter AP LAT (D )(c) and effective diameter ratio (D )(d). Correlation coefficients were 0.83, 0.84, 0.88, and 0.48, respectively (p < 0.001) E RATIO O’Neill et al. European Radiology Experimental (2018) 2:38 Page 4 of 8 Table 2 Summary of body mass index category and midslice diameter measurements D (cm) D (cm) D (cm) D AP LAT E RATIO Overall (n = 50) 24.77 ± 4.53 31.53 ± 3.9 27.79 ± 4.12 1.23 ± 0.13 Underweight (n = 6) 19.27 ± 1.52 27.42 ± 2.23 22.85 ± 2.03 1.16 ± 0.07 Normal weight (n = 26) 23.12 ± 2.74 30.23 ± 1.92 26.22 ± 2.16 1.22 ± 0.11 Overweight (n = 12) 27.35 ± 2.62 32.71 ± 2.37 29.88 ± 2.13 1.2 ± 0.1 Obese (n = 6) 32.22 ± 3.65 38.92 ± 3.89 35.34 ± 2.84 1.39 ± 40.23 BMI body mass index; data as means ± standard deviations of the mean 2 2 2 2 Underweight referred to BMI < 18.5 kg/m , normal weight referred to 18.5 ≤ BMI < 25 kg/m , overweight referred to 25 ≤ BMI < 30 kg/m , obese referred to BMI ≥ 30 kg/m Fig. 3 Scatterplots show: volume-computed tomography dose index (CTDI ) for body mass index (BMI) (a) and effective diameter (b) with correlation vol r values of 0.85 and 0.9, respectively; dose length product (DLP) for BMI (c) and effective diameter (d)with r correlation values of 0.84 and 0.89, respectively; size-specific dose estimate (SSDE) for BMI (e) and effective diameter (f)with r correlation values of 0.87 and 0.88, respectively; effective dose for BMI (g)and effective diameter (h)with r correlation values of 0.84 and 0.87, respectively O’Neill et al. European Radiology Experimental (2018) 2:38 Page 5 of 8 is calculated as the geometric mean of D and D , between BMI, dose indices, and body diameter measure- AP LAT as follows: ments were examined with Pearson correlation analysis (r). Linear regression models were used to assess the de- D ¼ √ðÞ D D E AP LAT pendence of CTDI, DLP, SSDE, and effective dose on BMI. Linear regression models were also used to estimate the relationship of effective diameter (independent vari- The outer D (D ) equates to the conventional D E OUT E able) with BMI (dependent variable). A p-value lower than calculated using the AAPM method described above. 0.05 was taken to indicate statistical significance. The inner D (D ) is derived using the anteroposterior E IN (D ) and lateral diameters (D ) measured on AP(IN) LAT(IN) Results an axial CT image at the midslice level, excluding the Patient demographics subcutaneous adipose tissue (Fig. 1c). The D is then IN The study population (n = 50) comprised 19 men and 31 calculated as the geometric mean of D and AP(IN) women with an age of 37.9 ± 14.4 years (mean ± standard D ,asfollows: LAT(IN) deviation [SD], ranging from 17 to 73 years. D ¼ √ D D IN APðÞ IN LATðÞ IN BMI and dose metrics The D ratio (D ), another patient size-related E RATIO The overall BMI was 24.6 ± 4.8 kg/m (mean ± SD), ran- metrics proposed by Lamoureux et al. [7], was also ging from 17.4 to 38.8 kg/m . The mean CTDI , DLP, vol calculated, as follows: SSDE and effective dose measurements overall, and when stratified for BMI, are listed in Table 1. D ¼ D =D RATIO OUT IN Body diameter measurements Statistical analysis The overall D , D , D and D were 24.8 ± AP LAT AP + LAT E Data were collated using Microsoft Excel 2010 (Microsoft 4.5 cm, 31.5 ± 3.9 cm, 56.3 ± 7.9 cm, and 27.8 ± 4.1 cm Corporation, Redmond, WA, USA) and statistical analyses (mean ± SD), respectively. The effective diameter ratio were conducted by using Microsoft Excel 2010 and (D ) was 1.23 ± 0.13 (mean ± SD). The correlations RATIO GraphPad Prism version 5.0 (GraphPad Software Inc., San between BMI and diameter are shown in Fig. 2. Overall, Diego, CA, USA). Descriptive statistics including means, the best correlation was found with D (0.88), where standard deviations and ranges were calculated. BMI, dose correlations between mean BMI and mean body diame- indices (CTDI , DLP, SSDE, effective dose) and body di- ters were highly significant (p < 0.001). vol ameters (D , D , D D , D D ) were recorded Mean BMI and body diameters across BMI subgroups AP LAT AP+ LAT E, RATIO for each patient CT examination. The correlations are shown in Table 2. Excluding D , the other body RATIO Fig. 4 Scatterplot of body mass index (BMI) as a function of effective diameter. Linear regression trend line equation: D = 0.76(BMI) + 9.4 E O’Neill et al. European Radiology Experimental (2018) 2:38 Page 6 of 8 diameters strongly correlated with each other. The cor- Table 3 Conversion factors to convert volume-computed- tomography dose index (CTDI ) to size-specific dose estimate relation coefficients (r) were 0.78 for D − D , 0.96 vol AP LAT (SSDE) based on body mass index (BMI) for D − D , and 0.92 for D − D ,(p < 0.001 for all). AP E LAT E BMI D CTDI /SSDE conversion factor There was a moderate correlation between D and E vol LAT D with a correlation coefficient of 0.62 (p < 0.001) 15 20.8 1.73 RATIO and weak but statistically significant correlations be- 16 21.6 1.68 tween D and D (r = 0.34, p = 0.016) and D and AP RATIO E 17 22.3 1.63 D (r = 0.49, p < 0.001). A stronger correlation was RATIO 18 23.1 1.59 found between D and D (r = 0.99, p < 0.001) than AP + LAT E 19 23.8 1.54 with either D or D alone and D [5]. AP LAT E 20 24.6 1.50 Both BMI and effective body diameter correlated strongly with all the dose metrics analysed (p < 0.001), 21 25.4 1.46 with r values ranging from 0.84 to 0.90. A weaker but 22 26.1 1.42 significant correlation of D with each dose metric RATIO 23 26.9 1.38 was found: r values ranged from 0.45 to 0.48 (p ≤ 0.05). 24 27.6 1.34 These data are summarised in Fig. 3. 25 28.4 1.31 The equation of the linear regression trend-line plot- 26 29.2 1.27 ting effective diameter as a function of BMI is as follows: y = 0.76(x) + 9.4 (Fig. 4). Utilising this equation, the pa- 27 29.9 1.23 tient’s BMI (x) can be used to calculate an estimate for 28 30.7 1.20 the effective diameter (y), i.e. D = 0.76(BMI) + 9.4. 29 31.4 1.17 Table 3 demonstrates a list of conversion factors to cal- 30 32.2 1.14 culate SSDE from CTDI based on the BMI of the vol 31 33.0 1.10 patient. 32 33.7 1.07 Discussion 33 34.5 1.04 CTDI indicates the amount of radiation delivered by vol 34 35.2 1.02 the scanner for a specific CT examination, calculated on 35 36.0 0.99 the basis of a standardised and homogenous phantom 36 36.8 0.96 study. It is a precisely defined metrics that is displayed 37 37.5 0.93 on the dose protocol of every CT scanner and is a meas- 38 38.3 0.91 ure of scanner radiation output, indicating how much radiation is directed toward the patient rather than 39 39.0 0.88 quantifying how much radiation a patient receives [2]. 40 39.8 0.86 Increasing use of CT and concerns regarding radiation 41 40.6 0.84 dose from medical imaging, however, increase the need 42 41.3 0.81 for imaging providers to facilitate accurate estimation of 43 42.1 0.79 radiation dose to patients. 44 42.8 0.77 SSDE is a dose parameter that takes into consideration corrections based on the size of the patient from linear 45 43.6 0.75 dimensions measured on the patient images. SSDE is an 46 44.4 0.73 estimate of the mean dose to the centre of the scan vol- 47 45.1 0.71 ume for an object having similar attenuation characteris- 48 45.9 0.69 tics as a given patient; it is not a direct measurement of 49 46.6 0.67 dose to a specific patient [8]. This metrics provides the 50 47.4 0.65 ability to estimate the average radiation dose to a patient BMI body mass index, CTDI volume-computed-tomography dose index, in a clinical setting, albeit with 10–20% variability of the vol D effective diameter, SSDE size-specific dose estimate dose estimate from the actual received dose, even when patient size is taken into account [3]. The AAPM report [3] recommends that the SSDE for each patient be esti- Khawaja et al. [6] demonstrated body weight to be a mated prior to CT scan using patient size parameters to more simple and convenient measure than effective diam- best optimise the scanning parameters to achieve the eter to estimate SSDE in paediatric patients at the time of diagnostic quality CT images with the lowest necessary CT scanning. They argued that measurement of body radiation dose. diameters in clinical practice is awkward, inconvenient, O’Neill et al. European Radiology Experimental (2018) 2:38 Page 7 of 8 time-consuming and open to interobserver variability, diameter range, 19–39.4), BMI measurements correlated particularly in the absence of a automated methods of strongly with diameters. The use of BMI to calculate measurement. An overview of other attempts to estimate SSDE has been shown to be a valid alternative to the the radiation dose in CT is presented in Table 4 [9–13]. traditional methods for manual measurement of We hypothesised that BMI, being a composite measure- anterior-posterior and lateral-lateral dimensions using ment derived from both weight and height, may also rep- the electronic callipers available on the PACS. A recent resent an appropriate indicator of patient size to use in study by Babak Alikhani et al. [15] showed that in lieu of effective diameter in predicting SSDE. BMI is an abdominal CT, the size-dependent conversion factor easily, and often routinely, obtained measurement in clin- (f size) closely correlated with patient BMI, indicated ical practice. It is an objective measure with limited bias by the exponentially decreasing f size values with in- or interobserver variability during calculation [14]. creasing BMI. The current study echoes these results The present study assessed relevant size metrics and with the proposition that BMI can act as a surrogate demonstrated a very strong correlation between effective for determining effective body diameter. diameter and SSDE (r = 0.88 or 0.87; p < 0.001) with The effective diameter ratio (D )isanewmet- RATIO BMI, indicating that BMI is an accurate alternative to ef- rics proposed by Lamoureux et al. [7] as a supple- fective diameter for SSDE estimation in abdominal CT. ment to patient-specific size parameter data and is, as Bias from other sources was minimised as all patients yet, not validated. D provides information about RATIO were scanned using a predefined and standardised CT anatomical composition, particularly the volume of abdomen and pelvis protocol on a single CT scanner by extra-abdominal adipose tissue but underestimates one of two radiographers. This paper demonstrates that intra-abdominal adiposity. It proved to be a much effective diameter can be accurately estimated using an weaker predictor of radiation dose to the patient in equation and patient BMI. SSDE can then be computed terms of CTDI , DLP and effective dose than either vol in a standard manner from CTDI by using AAPM effective diameter or BMI (p < 0.001) in the present vol look-up tables to derive conversion factors. paper. Findings suggest that while this metrics is a We found that in patients with a wide range of body good indicator of body fat distribution, it is subopti- habitus measurements (BMI range, 17.4–38.8; effective mal as a predictor of patient SSDE. Table 4 Examples of dose estimation on abdominal computed tomography (CT) Monte Carlo dose estimation with patient-specific Full-body computer model created based on the patient’s clinical CT data. Large organs anatomical models [9] individually segmented and modelled. Other organs were created by transforming an existing adult male or female full-body computer model to match the framework defined by the segmented organs, referencing the organ volume and anthropometry data in ICRP Publication 89. A Monte Carlo program (General Electric Lightspeed VCT-XTe, GE Healthcare, GE Medical Systems, Waukesha, WI, USA) was used to estimate patient-specific organ dose, from which effective dose and risks of cancer incidence were derived. Study suggests the construction of a large library of patient-specific computer models could estimate dose for any patient prior to or after a CT examination Automated measurement of effective diameter [10] Algorithm for estimating body-size diameter on axial CT slice implemented in Python and C#. Number of pixels whose Hounsfield unit exceeding a set threshold multiplied by the area of a single pixel to give an estimate of the area of the patient cross-section. Effective diameter computed as diameter of the circle whose area is the same as that of the cross-section. Correlation between the manual and automated measurements of effective diameter was very high Patient size modelled as a water-equivalent diameter Water-equivalent diameter (D ), automatically extracted from axial CT images and (D )[11] used to model patient size and subsequently to calculate size-specific dose estimates. The extracted D values correlate well with effective diameter (R of 0.90 for abdomen and pelvis) Dose estimation through directly using Thermoluminescent dosemeters (TLDs) and a Rando Alderson phantom used. Computer- thermoluminescent dosemeters (TLDs) [12] simulated dose estimation based on National Radiation Protection Board Monte Carlo simulations. Directly measured dose 18% higher than computer-simulated dosimetry, suggesting underestimation by computer-simulation techniques compared with TLD measurements Topogram-based body size indices for CT dose Linear regression of four topographical indices for estimation of D (i) average diameter; consideration and scan protocol optimisation [13] (ii) girth (cross-section modelled as ellipse); (iii) topogram projection area; (iv) improved topogram projection area (corrected for patient miscentering and water attenuation coefficient) Correlating body weight with diameter for radiation Anteroposterior and lateral diameters were measured manually and through automated dose estimates [6] software. Effective diameter subsequently calculated. Overall body weight had a strong correlation with diameter O’Neill et al. European Radiology Experimental (2018) 2:38 Page 8 of 8 Our study has some limitations. Our sample size is Ethics approval and consent to participate Approval for this study was granted by the Clinical Research Ethics Committee relatively low (n = 50), with patients chosen because of the Cork Teaching Hospitals, Lancaster Hall, 6 Little Hanover Street, Cork, standardised CT imaging on this well-characterised co- Ireland. Informed consent was obtained from each patient. hort had already been performed and BMI measure- Consent for publication ments were available for all of them; CT images and The consent for publication is included in the informed consent. data were readily available to test this hypothesis without the need to image further patients. A larger sample size Competing interests The authors declare that they have no competing interests. may strengthen the assessment of the relationship be- tween effective diameter and BMI. In addition, with a Publisher’sNote larger sample size, it could be possible to estimate trend Springer Nature remains neutral with regard to jurisdictional claims in lines stratified for BMI, which may lead to better esti- published maps and institutional affiliations. mates of diameter and hence of SSDE. Author details Due to the retrospective design of this study, BMI Department of Radiology, Cork University Hospital, Wilton, Cork, Ireland. measurements only were available rather than the con- 2 3 Department of Radiology, University College Cork, Cork, Ireland. APC stituent height and weights. Statistical evaluation of the Microbiome Ireland, University College Cork, Cork, Ireland. interplay of these parameters with BMI, body diameters Received: 18 June 2018 Accepted: 9 October 2018 and radiation dose may have yielded further supportive information. With the advent of automated body diam- References eter and SSDE measurement technology, the applicabil- 1. 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American Association of Physicists in Medicine (2014) Use of water equivalent friendly and reproducible. The present paper indicates diameter for calculating patient size and size-specific dose estimates (SSDE) in CT (Report 220). https://www.aapm.org/pubs/reports/RPT_220.pdf.Accessed that patient BMI can be used to accurately estimate ef- Sept 22 2018 fective diameter, obviating the need to measure antero- 5. Craig O, O’ Neill S, O’Neill F et al (2012) Diagnostic accuracy of computed posterior and lateral diameters in order to calculate tomography using lower doses of radiation for patients with Crohn’s disease. Clin Gastroenterol Hepatol 10:886–892 SSDE at the time of CT. 6. Khawaja RD, Singh S, Vettiyil B et al (2015) Simplifying size-specific radiation dose estimates in pediatric CT. AJR Am J Roentgenol 204:167–176 Abbreviations 7. Lamoureux R, Sinclair L, Mench A et al (2015) SU-E-I-28: introduction AAPM: American Association of Physicists in Medicine; BMI: Body mass index; and investigation of effective diameter ratios as a new patient size metric for CT: Computed tomography; CTDI : Volume CT dose index; D : Maximum vol AP use in CT. Med Phys 42:3247–3248 skin-to-skin anteroposterior diameter; D : Effective diameter; D : Inner D ; E IN E 8. Christner JA, Braun NN, Jacobsen MC, Carter RE, Kofler JM, McCollough CH D : Maximum skin-to-skin lateral diameter; DLP: Dose length product; LAT (2012) Size-specific dose estimates for adult patients at CT of the torso. D :Outer D ; D : Ratio between the internal and the external abdominal OUT E RATIO Radiology 265:841–847 diameters; PACS: Picture-archiving and communication system; SD: Standard 9. Li X, Samei E, Segars WP et al (2011) Patient-specific radiation dose and deviation; SSDE: Size-specific dose estimate cancer risk estimation in CT: part II. Application to patients. Med Phys 38:408–419 10. Cheng PM (2013) Automated estimation of abdominal effective diameter Availability of data and materials for body size normalization of CT dose. J Digit Imaging 26:406–411 The datasets used and/or analysed during the current study are available 11. Ikuta I, Warden GI, Andriole KP, Khorasani R, Sodickson A (2014) Estimating from the corresponding author on reasonable request. patient dose from x-ray tube output metrics: automated measurement of patient size from CT images enables large-scale size-specific dose estimates. Funding Radiology 270:472–480 Professor Denis O’Sullivan Research Fellowship, University College Cork, Cork, 12. Groves AM, Owen KE, Courtney HM et al (2004) 16-detector multislice CT: Ireland. dosimetry estimation by TLD measurement compared with Monte Carlo simulation. Br J Radiol 77:662–665 Authors’ contributions 13. Li B, Behrman RH, Norbash AM (2012) Comparison of topogram-based body SON is involved with study design, data acquisition and analysis, manuscript size indices for CT dose consideration and scan protocol optimization. Med drafting and revising. RGK is involved with data analysis, manuscript Phys 39:3456–3465 drafting and revising. BWC is involved with data analysis, manuscript 14. Sebo P, Beer-Borst S, Haller DM, Bovier PA (2008) Reliability of doctors’ drafting and revising. NM is involved with study design, data acquisition, anthropometric measurements to detect obesity. Prev Med 47:389–393 manuscript drafting and revising. MM is involved with study design, 15. Alikhani B, Getzin T, Kaireit TF et al (2018) Correlation of size-dependent manuscript drafting and revising. OJOC is involved with study design, conversion factor and body-mass-index using size-specific dose estimates data analysis, manuscript drafting and revising. All authors have given formalism in CT examinations. Eur J Radiol 100:130–134 final approval to manuscript publication and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
European Radiology Experimental – Springer Journals
Published: Nov 28, 2018
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