scholarly journals Development of CT Effective Dose Conversion Factors from Clinical CT Examinations in the Republic of Korea

Diagnostics ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 727
Author(s):  
Sang-Kyung Lee ◽  
Jung Su Kim ◽  
Sang-Wook Yoon ◽  
Jung Min Kim
Keyword(s):  
Effective Dose ◽  
Nationwide Survey ◽  
Adult Brain ◽  
Radiological Protection ◽  
Dose Length Product ◽  
Conversion Factors ◽  
Ct Dose ◽  
Ct Protocol ◽  
Ct Data ◽  
The Republic

The aim of this study was to determine the conversion factors for the effective dose (ED) per dose length product (DLP) for various computed tomography (CT) protocols based on the 2007 recommendations of the International Commission on Radiological Protection (ICRP). CT dose data from 369 CT scanners and 13,625 patients were collected through a nationwide survey. Data from 3793 patients with a difference in height within 5% of computational human phantoms were selected to calculate ED and DLP. The anatomical CT scan ranges for 11 scan protocols (adult-10, pediatric-1) were determined by experts, and scan lengths were obtained by matching scan ranges to computational phantoms. ED and DLP were calculated using the NCICT program. For each CT protocol, ED/DLP conversion factors were calculated from ED and DLP. Estimated ED conversion factors were 0.00172, 0.00751, 0.00858, 0.01843, 0.01103, 0.02532, 0.01794, 0.02811, 0.02815, 0.02175, 0.00626, 0.00458, 0.00308, and 0.00233 mSv∙mGy−1∙cm−1 for the adult brain, intra-cranial angiography, C-spine, L-spine, neck, chest, abdomen and pelvis, coronary angiography, calcium scoring, aortography, and CT examinations of pediatric brain of <2 years, 4–6 years, 9–11 years, and 13–15 years, respectively. We determined ED conversion factors for 11 CT protocols using CT data obtained from a nationwide survey in Korea and Monte Carlo-based dose calculations.

scholarly journals Evaluation of Effective Dose from CT Scans for Overweight and Obese Adult Patients Using the VirtualDose Software

2016 ◽  
Vol 174 (2) ◽  
pp. 216-225 ◽  
Author(s):  
Baohui Liang ◽  
Yiming Gao ◽  
Zhi Chen ◽  
X. George Xu
Keyword(s):  
Effective Dose ◽  
Normal Weight ◽  
Ct Scans ◽  
Radiological Protection ◽  
Obese Patients ◽  
Tube Voltage ◽  
Dose Length Product ◽  
Conversion Factors ◽  
Tissue Weight ◽  
Weight Factors

Abstract This paper evaluates effective dose (ED) of overweight and obese patients who undergo body computed tomography (CT) examinations. ED calculations were based on tissue weight factors in the International Commission on Radiological Protection Publication 103 (ICRP 103). ED per unit dose length product (DLP) are reported as a function of the tube voltage, body mass index (BMI) of patient. The VirtualDose software was used to calculate ED for male and female obese phantoms representing normal weight, overweight, obese 1, obese 2 and obese 3 patients. Five anatomic regions (chest, abdomen, pelvis, abdomen/pelvis and chest/abdomen/pelvis) were investigated for each phantom. The conversion factors were computed from the DLP, and then compared with data previously reported by other groups. It was observed that tube voltage and BMI are the major factors that influence conversion factors of obese patients, and that ED computed using ICRP 103 tissue weight factors were 24% higher for a CT chest examination and 21% lower for a CT pelvis examination than the ED using ICRP 60 factors. For body CT scans, increasing the tube voltage from 80 to 140 kVp would increase the conversion factors by as much as 19–54% depending on the patient's BMI. Conversion factor of female patients was ~7% higher than the factors of male patients. DLP and conversion factors were used to estimate ED, where conversion factors depended on tube voltage, sex, BMI and tissue weight factors. With increasing number of obese individuals, using size-dependence conversion factors will improve accuracy, in estimating patient radiation dose.

scholarly journals Whole Body Low Dose Computed Tomography Using Third-Generation Dual-Source Multidetector With Spectral Shaping: Protocol Optimization and Literature Review

Dose-Response ◽  
2020 ◽  
Vol 18 (4) ◽  
pp. 155932582097313
Author(s):  
Dario Baldi ◽  
Liberatore Tramontano ◽  
Vincenzo Alfano ◽  
Bruna Punzo ◽  
Carlo Cavaliere ◽  
...  
Keyword(s):  
Effective Dose ◽  
Low Dose ◽  
Whole Body ◽  
Dose Length Product ◽  
Osteolytic Lesions ◽  
Subjective Image Quality ◽  
Ct Dose ◽  
Dual Source ◽  
Ct Dose Index ◽  
Low Dose Computed Tomography

For decades, the main imaging tool for multiple myeloma (MM) patient’s management has been the conventional skeleton survey. In 2014 international myeloma working group defined the advantages of the whole-body low dose computed tomography (WBLDCT) as a gold standard, among imaging modalities, for bone disease assessment and subsequently implemented this technique in the MM diagnostic workflow. The aim of this study is to investigate, in a group of 30 patients with a new diagnosis of MM, the radiation dose (CT dose index, dose-length product, effective dose), the subjective image quality score and osseous/extra-osseous findings rate with a modified WBLDCT protocol. Spectral shaping and third-generation dual-source multidetector CT scanner was used for the assessment of osteolytic lesions due to MM, and the dose exposure was compared with the literature findings reported until 2020. Mean radiation dose parameters were reported as follows: CT dose index 0.3 ± 0.1 mGy, Dose-Length Product 52.0 ± 22.5 mGy*cm, effective dose 0.44 ± 0.19 mSv. Subjective image quality was good/excellent in all subjects. 11/30 patients showed osteolytic lesions, with a percentage of extra-osseous findings detected in 9/30 patients. Our data confirmed the advantages of WBLDCT in the diagnosis of patients with MM, reporting an effective dose for our protocol as the lowest among previous literature findings.

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:&lt;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.

scholarly journals A review of dental cone-beam CT dose conversion coefficients

2020 ◽  
pp. 20200225
Author(s):  
Eugene Mah ◽  
E Russell Ritenour ◽  
Hai Yao
Keyword(s):  
Effective Dose ◽  
Cone Beam Ct ◽  
Field Of View ◽  
Cone Beam ◽  
Tube Voltage ◽  
Conversion Factors ◽  
Dose Area Product ◽  
Ct Dose ◽  
Conversion Coefficients ◽  
Area Product

Objective: The purpose of this study was to review the literature to examine the usage and magnitude of effective dose conversion factors (DCE) for dental cone beam CT (CBCT) scanners. Methods: A PubMed literature search for publications relating to radiation dosimetry in dental radiography was performed. Papers were included if they reported DCE, or reported ICRP 103 effective dose and dose-area product. 71 papers relating to dental CBCT dosimetry were found, of which eight reported effective dose conversion factors or provided enough information to calculate dose conversion factors. Scanner model, effective dose, dose-area product, tube voltage, field of view size and DCE were extracted from the papers for analysis. Results: DCE values ranged from 0.035 to 0.31 µSv/mGy-cm2 with a mean of 0.129 µSv/mGy-cm2 (SD = 0.056). When categorized into small (<100 cm2), medium (100–225 cm2) and large (>225 cm2) fields of view (FOV), linear fits to the effective dose and dose-area product yielded slopes of 0.129, 0.111 and 0.074 µSv/mGy-cm2 for small, medium and large FOVs respectively. Conclusion: The range of reported DCE values and spread with respect to field of view category suggests that DCE values that depend on FOV would provide more accurate effective dose estimates. Tube voltage was found to be a smaller factor in determining DCE. Reasonable values for DCE taking into account FOV size were obtained. There is considerable room for more work to be done to examine the behaviour of DCE with changes to patient age and dental CBCT imaging parameters.

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