scholarly journals Reference phantom selection in pediatric computed tomography using data from a large, multicenter registry

2021 ◽  
Author(s):  
Philip W. Chu ◽  
Sophronia Yu ◽  
Yifei Wang ◽  
J. Anthony Seibert ◽  
Luisa F. Cervantes ◽  
...  
Keyword(s):  
Computed Tomography ◽  
San Francisco ◽  
Body Region ◽  
Dose Length Product ◽  
Actual Usage ◽  
Ct Dose ◽  
Reference Phantom ◽  
Usage Patterns ◽  
Dose Metrics ◽  
Using Data

Abstract Background Radiation dose metrics vary by the calibration reference phantom used to report doses. By convention, 16-cm diameter cylindrical polymethyl-methacyrlate phantoms are used for head imaging and 32-cm diameter phantoms are used for body imaging in adults. Actual usage patterns in children remain under-documented. Objective This study uses the University of California San Francisco International CT Dose Registry to describe phantom selection in children by patient age, body region and scanner manufacturer, and the consequent impact on radiation doses. Materials and methods For 106,837 pediatric computed tomography (CT) exams collected between Jan. 1, 2015, and Nov. 2, 2020, in children up to 17 years of age from 118 hospitals and imaging facilities, we describe reference phantom use patterns by body region, age and manufacturer, and median and 75th-percentile dose–length product (DLP) and volume CT dose index (CTDIvol) doses when using 16-cm vs. 32-cm phantoms. Results There was relatively consistent phantom selection by body region. Overall, 98.0% of brain and skull examinations referenced 16-cm phantoms, and 95.7% of chest, 94.4% of abdomen and 100% of cervical-spine examinations referenced 32-cm phantoms. Only GE deviated from this practice, reporting chest and abdomen scans using 16-cm phantoms with some frequency in children up to 10 years of age. DLP and CTDIvol values from 16-cm phantom-referenced scans were 2–3 times higher than 32-cm phantom-referenced scans. Conclusion Reference phantom selection is highly consistent, with a small but significant number of abdomen and chest scans (~5%) using 16-cm phantoms in younger children, which produces DLP values approximately twice as high as exams referenced to 32-cm phantoms

Comparison of Radiation Dose in CT Examinations At PIMS with European Commission Reference Doses

2021 ◽  
Vol 17 (3) ◽  
pp. 216-221
Author(s):  
Fawad Yasin ◽  
Anum Rasheed ◽  
Muhammad Nauman Malik ◽  
Farheen Raza ◽  
Ramish Riaz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Radiation Dose ◽  
European Commission ◽  
Large Scale ◽  
Radiology Department ◽  
Radiation Doses ◽  
Diagnostic Reference Levels ◽  
Reference Levels ◽  
Dose Length Product ◽  
Ct Dose

OBJECTIVE - The purpose of this study was to assess the radiation dose levels from common computed tomography (CT) examinations performed in Radiology Department of Pakistan Institute of Medical Sciences (PIMS), and evaluate these according to diagnostic reference levels (DRLs) proposed by European Commission (EC) guidelines, and thus contributing towards the establishment of local and national DRLs. To the best of our knowledge, this is the first study of its kind to explore radiation doses from CT examinations in Pakistan. STUDY DESIGN - This was a quantitative study conducted at PIMS, Islamabad, spanning a duration of eight weeks. Scan parameters and dose profile data of 1506 adults undergoing examinations of head, neck, chest and abdomen-pelvis regions, comprising of single- and multi-phase, contrast-enhanced and unenhanced studies. Dose indicators utilized by EC guidelines for DRLs include volume CT dose index (CTDIvol) and Dose Length Product (DLP) for single slice and complete examination radiation doses, respectively. METHOD - Values of CTDIvol, DLP and scan lengths were extracted from the CT operators console. Other control variables included gender, contrast enhancement and phasicity of study. IBM SPSS package was used to obtain descriptive statistics such as mean and quartiles. RESULTS - DRLs calculated as 75th percentile of CTDIvol, DLP for various anatomical regions are by and far comparable to European DRLs. CONCLUSION – This study describes institutional diagnostic reference levels for common CT exams in Islamabad and provides benchmark values for future reference. Our DRL values are mostly comparable to European and international DRLs. Similar, albeit large scale, surveys are recommended for establishment of local and national DRLs, eventually contributing towards development of regional DRLs. KEYWORDS: CTDIvol, DLP, Diagnostic Reference Levels, Computed Tomography, Radiation Monitoring, Scan length

CT dosimetry at the Australian Synchrotron for 25–100 keV photons and 35–160 mm-diameter biological specimens

2019 ◽  
Vol 26 (2) ◽  
pp. 517-527
Author(s):  
Stewart Midgley ◽  
Nanette Schleich ◽  
Alex Merchant ◽  
Andrew Stevenson
Keyword(s):  
Effective Dose ◽  
Beam Quality ◽  
Absorbed Dose ◽  
Body Region ◽  
Average Dose ◽  
Dose Length Product ◽  
Organ Doses ◽  
Ct Dose ◽  
Radiation Output ◽  
Ct Dosimetry

The dose length product (DLP) method for medical computed tomography (CT) dosimetry is applied on the Australian Synchrotron Imaging and Medical Beamline (IMBL). Beam quality is assessed from copper transmission measurements using image receptors, finding near 100% (20 keV), 3.3% (25 keV) and 0.5% (30–40 keV) relative contributions from third-harmonic radiation. The flat-panel-array medical image receptor is found to have a non-linear dose response curve. The amount of radiation delivered during an axial CT scan is measured as the dose in air alone, and inside cylindrical PMMA phantoms with diameters 35–160 mm for mono-energetic radiation 25–100 keV. The radiation output rate for the IMBL is comparable with that used for medical CT. Results are presented as the ratios of CT dose indices (CTDI) inside phantoms to in air with no phantom. Ratios are compared for the IMBL against medical CT where bow-tie filters shape the beam profile to reduce the absorbed dose to surface organs. CTDI ratios scale measurements in air to estimate the volumetric CTDI representing the average dose per unit length, and the dose length product representing the absorbed dose to the scanned volume. Medical CT dose calculators use the DLP, beam quality, axial collimation and helical pitch to estimate organ doses and the effective dose. The effective dose per unit DLP for medical CT is presented as a function of body region, beam energy and sample sizes from neonate to adult.

DIAGNOSTIC REFERENCE LEVELS FOR PAEDIATRIC HEAD COMPUTED TOMOGRAPHY IN MOROCCO: A NATIONWIDE SURVEY

2020 ◽  
Vol 191 (4) ◽  
pp. 400-408
Author(s):  
M Benmessaoud ◽  
A Dadouch ◽  
M Talbi ◽  
M Tahiri ◽  
Y El-ouardi
Keyword(s):  
Computed Tomography ◽  
Nationwide Survey ◽  
Diagnostic Reference Levels ◽  
Reference Levels ◽  
Dose Length Product ◽  
Head Ct ◽  
Ct Dose ◽  
Starting Point ◽  
Effective Doses ◽  
Head Computed Tomography

Abstract The purpose of this study was to establish the diagnostic reference levels (DRLs) for paediatric head computed tomography (CT) in Morocco and to assess the effective doses received during head CT examinations. The data of 1007 patients were collected retrospectively from Moroccan university children’s hospitals. The sample was classified per age group:<1, 1–5, 5–10 and 10–15 years. The proposed DRLs were defined as 75th percentile of the distributions, which were in terms of CT dose index of 26.98, 28.88, 34.00 and 38.20 mGy and dose length product of 461.64, 540.06, 627.20 and 705.98 mGy.cm, respectively. The effective doses estimated were 3.6, 2.9, 2 and 1.79 mSv, respectively. The DRLs reported in Morocco were compared with those of other countries, which were based on the same age grouping method, including Thailand, Switzerland, Japan and the international DRLs. Our initiative via the determination of the first Moroccan diagnostic reference levels for paediatric head CT must be a starting point to spread this investigation towards other examinations and imaging modalities.

TOWARD NATIONAL CT DIAGNOSTIC REFERENCE LEVELS IN THE UNITED ARAB EMIRATES: A MULTICENTER REVIEW OF CT DOSE INDEX AND DOSE LENGTH PRODUCT

2020 ◽  
Vol 190 (3) ◽  
pp. 243-249
Author(s):  
Mohamed M Abuzaid ◽  
Wiam Elshami ◽  
A El Serafi ◽  
T Hussien ◽  
J R McConnell ◽  
...  
Keyword(s):  
Computed Tomography ◽  
United Arab Emirates ◽  
Patient Characteristics ◽  
Diagnostic Reference Levels ◽  
Reference Levels ◽  
Dose Length Product ◽  
Ct Dose ◽  
Ct Head ◽  
Computed Tomography Dose Index ◽  
Dose Index

Abstract This multicenter study evaluated computed tomography dose index volume (CTDIvol) and dose length product (DLP) to contribute to establishing computed tomography (CT) national diagnostic reference levels (NDRLs) in the United Arab Emirates (UAE). Data from 240 patients, who underwent CT head, chest, abdomen–pelvis and urography examinations, were analyzed, including patient age, sex and weight, CTDIvol (mGy) and DLP (mGy cm). The proposed DRLs for each examination were calculated as the third quartile. DRLs are proposed using CTDIvol (mGy) and DLP (mGy cm) for CT head (67 and 1189, respectively), chest (8 and 302, respectively), abdomen–pelvis (28 and 1122, respectively) and urography (20 and 714, respectively). These values are comparable with the initial NDRLs and published international DRLs. Baseline values for International Radiology Center (IRC) CT DRLs were calculated on frequently performed CT examinations. Implementation of DRL values improves dose optimization based on procedures, scanner type and patient characteristics while maintaining acceptable image quality and diagnostic confidence.

OPTIMIZATION OF RADIATION DOSE IN CT IMAGING: ESTABLISHING THE INSTITUTIONAL DIAGNOSTIC REFERENCE LEVELS AND PATIENT DOSE AUDITING

2019 ◽  
Vol 188 (2) ◽  
pp. 213-221 ◽  
Author(s):  
Mohd Amir Syahmi Mat Razali ◽  
Muhamad Zabidi Ahmad ◽  
Ibrahim Lutfi Shuaib ◽  
Noor Diyana Osman
Keyword(s):  
Dose Distribution ◽  
Population Characteristics ◽  
Contrast Study ◽  
Diagnostic Reference Levels ◽  
Reference Levels ◽  
Dose Length Product ◽  
Ct Dose ◽  
Dose Metrics ◽  
Ct Technology ◽  
Ct Dose Index

Abstract The aim of this study was to propose local diagnostic reference levels (LDRLs) for the most common computed tomography (CT) examinations (including contrast and non-contrast scan phase) performed at Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia (USM), Malaysia. A retrospective CT dose survey of 1488 subjects from January 2015 until December 2018 was performed at AMDI USM, Malaysia. The proposed DRLs were established at 50th and 75th percentile of dose distribution for all dose metrics (CT dose index [CTDI]; CTDIvol, CTDIw and dose–length product). The proposed LDRLs were compared with national DRLs and other established DRLs. The 10 most common CT examinations at AMDI were thorax–abdomen–pelvis (TAP) CT (46%), followed by pelvis CT (17%), abdomen–pelvis CT (10%), brain/head CT (9%) and other CT protocols. The local DRLs were established using the third quartile values of dose distribution and were categorized based on CT region protocols. Most of the proposed DRLs were exceeded the national DRLs (63%) and other international DRLs (67%). From the dose auditing, almost half of the recent dose data (for year 2018) exceeded the proposed local DRLs and the unusual dose were observed in TAP, brain/head and pelvis CT examinations. The unusual higher dose could be due to higher mAs settings, higher number of scan phase for contrast study and higher pitch factor. The local DRLs should be established for dose optimization and reduction of the occurrence of excessive radiation exposure to the patients. The establishment of the Ads and LDRLs should also consider all the factors that affect the variation in DRLs such as CT technology, scanning protocols and population characteristics. The local dose distribution should always be revised for improvement of the current local practice.

Experimental Examination of Radiation Doses Of Dual- and Single-Energy Computed Tomography in Chest And Upper Abdomen in a Phantom Study

2021 ◽  
Author(s):  
Denise Bos ◽  
Britta König ◽  
Sebastian Blex ◽  
Sebastian Zensen ◽  
Marcel Opitz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pulmonary Arteries ◽  
Phantom Study ◽  
Radiation Doses ◽  
Experimental Examination ◽  
Dose Length Product ◽  
Ct Dose ◽  
Dual Source ◽  
Ct Dose Index ◽  
Upper Abdomen

Abstract The aim of this phantom study is to examine radiation doses of dual- and single-energy computed tomography (DECT and SECT) in the chest and upper abdomen for three different multi-slice CT scanners. A total of 34 CT protocols were examined with the phantom N1 LUNGMAN. Four different CT examination types of different anatomic regions were performed both in single- and dual-energy technique: chest, aorta, pulmonary arteries for suspected pulmonary embolism and liver. Radiation doses were examined for the CT dose index CTDIvol and dose-length product (DLP). Radiation doses of DECT were significantly higher than doses for SECT. In terms of CTDIvol, radiation doses were 1.1–3.2 times higher, and in terms of DLP, these were 1.1–3.8 times higher for DECT compared with SECT. The third-generation dual-source CT applied the lowest dose in 7 of 15 different examination types of different anatomic regions.

scholarly journals Paediatric CT Dose Optimization in a General Hospital

2019 ◽  
Vol 13 (1) ◽  
pp. 138
Author(s):  
Vivian Heidorne Guerra ◽  
Denise Yanikian Nersissian ◽  
Camila Souza Melo ◽  
Caio Vasconcellos ◽  
Rebeca Gonçalves Freitas ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Pediatric Patients ◽  
Optimization Process ◽  
Diagnostic Image Quality ◽  
Dose Length Product ◽  
Diagnostic Image ◽  
Ct Dose ◽  
Computed Tomography Scans ◽  
Absorbed Radiation Dose ◽  
Computed Tomography Dose Index

This work presents a methodology for the optimization of protocols applied to pediatric patients who underwent brain and chest computed tomography examinations. The implementation of this methodology aims to reduce the dose of ionizing radiation delivered to patients and the consequent risk associated with radiation, without decreasing the diagnostic image quality. The comparison between the results of CTDIvol (computed tomography dose index) and DLP (dose-length product) dosimetric quantities before the optimization process and their corresponding results after the implementation of the optimization process was done through boxplot graphs. It is noteworthy that the implementation of this methodology allows reductions in the range between 18 and 50% of the dosimetric values evaluated in this study. In addition, the case of brain computed tomography scans, in which the cohort of the evaluated patients is larger, is a highlight, which should also reflect in the reduction of the absorbed radiation dose by this particularly important group of patients.

scholarly journals Validation of a Locally Designed Computed Tomography Dose Phantom: A Comparison Study with a Standard Acrylic Phantom in South-South, Nigeria

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Anwuli Christiana Tobi ◽  
Chukwuka Emmanuel Mokobia ◽  
Joyce Ekeme Ikubor ◽  
Akintayo Daniel Omojola
Keyword(s):  
Computed Tomography ◽  
Cylindrical Shape ◽  
Correction Factors ◽  
Energy Agency ◽  
Dose Length Product ◽  
Ct Dose ◽  
Volume Computed Tomography ◽  
The Mean ◽  
Computed Tomography Dose Index ◽  
Dose Measurements

Purpose: The aim of this study was to determine the mean volume computed tomography dose index (CTDIvol) for the standard head and body phantoms and locally designed head and body phantoms respectively. Similarly, this study determined and compared the displayed mean CTDIvol and Dose Length Product (DLP) for the above phantoms from the CT monitor. In addition, the percentage deviations of both phantoms were compared with the recommended limits from the International Atomic Energy Agency (IAEA) and the American College of Radiologists (ACR). Materials and Methods: Dose measurements were made using a standard polymethymethacrylate (PMMA) phantom for head and body as well as a locally designed phantom with four CT scanners using thermoluminescence dosimeters (TLDs). The locally designed phantoms were made using a PMMA sheet, which was bent to give the desired cylindrical shape and was made like the standard phantoms. The constructed phantom was filled with water and the TLD chips were inserted into the center and peripheries of the phantoms to obtain the absorbed doses. Results: The CTDIvol for the standard head and body phantom for center A was 66.97 and 21.85mGy and for B was 23.39 and 6.29mGy respectively. Similarly, the CTDIvol for the constructed head and body phantom for center A was 63.91 and 19.84mGy and for B was 24.67 and 6.30mGy respectively. The uncertainty between the standard and constructed head phantoms for centers A and B was 4.6 and 5.5% respectively, while that of the standard and constructed body phantoms for centers A and B was 9.2 and 0.0% respectively. The maximum percent deviation from the console CTDIvol and DLP values with the four phantoms for centers A and B was within ±20%. The mean correction factors for the head and body were 0.998 and 1.05 respectively. Conclusion: The uncertainties obtained in this study were within the IAEA and ACR recommended value of ±20%. The constructed phantom proved useful for CT dose measurements.

VOLUME CT DOSE INDEX AND DOSE-LENGTH PRODUCT VALUES ACCORDING TO FACILITY SIZE IN JAPAN

2020 ◽  
Vol 188 (2) ◽  
pp. 261-269
Author(s):  
Yuta Matsunaga ◽  
Yuya Kondo ◽  
Kenichi Kobayashi ◽  
Masanao Kobayashi ◽  
Kazuyuki Minami ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Contrast Agent ◽  
Ct Scanner ◽  
Dose Length Product ◽  
Ct Dose ◽  
Volume Computed Tomography ◽  
Ct Dose Index ◽  
Computed Tomography Dose Index ◽  
Facility Size ◽  
Dose Index

Abstract The aim of this study was to investigate differences in volume computed tomography dose index (CTDIvol) and dose-length product (DLP) values according to facility size in Japan. A questionnaire survey was sent to 3000 facilities throughout Japan. Data from each facility were collected including bed number, computed tomography (CT) scan parameters employed and the CTDIvol and/or DLP values displayed on the CT scanner during each examination. The CTDIvol and DLP for 11 adult and 6 paediatric CT examinations were surveyed. Comparison of CTDIvol and DLP values of each examination according to facility size revealed key differences in CT dose between small and large facilities. This study highlights the importance of lowering the dose of coronary artery examination with contrast agent in smaller facilities and of lowering the dose of adult and paediatric head CT without contrast agent in larger facilities. The results of this study are valid in Japan.

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