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 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 Assessment of Organ and Effective Doses Received by Paediatric Patients Undergoing Computed Tomography Examinations in Three Hospitals in Brazzaville, Congo Republic: An Urgent Necessity for Regulatory Control

2021 ◽  
pp. 527-550
Author(s):  
J. Bazoma ◽  
G. B. Dallou ◽  
P. Ondo Meye ◽  
C. Bouka Biona ◽  
Saïdou ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Effective Dose ◽  
Absorbed Dose ◽  
Regulatory Control ◽  
Ct Scans ◽  
Radiological Protection ◽  
Age Group ◽  
Organ Doses ◽  
Paediatric Patients ◽  
Effective Doses

The present study aimed at estimating organ and effective doses from computed tomography (CT) scans of paediatric patients in three hospitals in Brazzaville, Congo Republic. A total of 136 data on paediatric patients, from 0.25 (3 months) to 15 years old, who underwent head, chest, abdomen – pelvis (AP) and chest – abdomen – pelvis (CAP) CT scans was considered. The approach followed in the present study to compute organ doses was to use pre-calculated volume CT dose index (CTDIvol) – and 100 milliampere-second (mAs) – normalized organ doses determined by Monte Carlo (MC) simulation. Effective dose were then derived using the international commission on radiological protection (ICRP) publications 60 and 103 formalism. For comparison purposes, effective dose were also computed using dose-length product (DLP) – to – effective dose conversion factors. A relatively high variation in organ and effective doses was observed in each age group due to the dependence of patient dose on the practice of technicians who perform the CT scan within the same facility or from one facility to another, patient size and lack of adequate training of technicians. In the particular case of head scan, the brain and the eye lens were delivered maximum absorbed doses of 991.81 mGy and 1176.51 mGy, respectively (age group 10-15 y). The maximum absorbed dose determined for the red bone marrow was 246.08 mGy (age group 1-5 y). This is of concern as leukaemia and brain tumours are the most common childhood cancers and as the ICRP recommended absorbed dose threshold for induction of cataract is largely exceeded. Effective doses derived from MC calculations and ICRP publications 60 and 103 tissues weighting factors showed a 0.40-17.61 % difference while the difference between effective doses derived by the use of k- factors and those obtained by MC calculations ranges from 0.06 to 224.87 %. The study has shown that urgent steps should be taken in order to significantly reduce doses to paediatric patients to levels observed in countries where dose reduction techniques are successfully applied.

EVALUATION OF IRRADIATION DOSES DELIVERED TO PATIENTS IN COMPUTED TOMOGRAPHY EXAMINATIONS IN 10 RADIOLOGY DEPARTMENTS IN DOUALA-CAMEROON

2020 ◽  
Vol 191 (3) ◽  
pp. 288-295
Author(s):  
Celestin Mpeke Mokubangele ◽  
Alexandre Ngwa Ebongue ◽  
Francisse Ouogue ◽  
Daniel Bongue ◽  
Boniface Moifo
Keyword(s):  
Computed Tomography ◽  
Ct Scan ◽  
Pediatric Population ◽  
Adult Population ◽  
Daily Practice ◽  
Ct Scans ◽  
Radiological Protection ◽  
Dose Length Product ◽  
Need To Evaluate ◽  
Adults And Children

Abstract Computed tomography (CT) scan is currently the most irradiating radio diagnostic procedure for the patients. The effective dose delivered by a CT-scan exploration corresponds to 1–20 years of natural irradiation of an individual. Hence, there is need to evaluate this medical exposure, in order to provide indicators and propose guidelines for its daily practice. The purpose of this work was to assess patient exposure levels due to CT-scan exams and propose a local diagnostic reference levels for the most common CT examinations performed in the radiology units of Douala/Cameroon. Data from 1775 CT scans, amongst which 10 different types of common CT examinations on adults and children, were collected, of which 1378 were adult CT scans and 397 were pediatric CT scans. The dose-length product (DLP) values in the adult population for head, abdomen–pelvic and lumber spine CT scans were high as compared to the Institute for Radiological Protection and Nuclear Safety recommendations and previous local DRL with an increase of 36, 15 and 23%, respectively. A general decrease of the DLP for CT-scans examinations in the pediatric population was observed.

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.

scholarly journals A dóziscsökkentés lehetőségei CT-képalkotás során az iteratív képrekonstrukció alkalmazásával

2019 ◽  
Vol 160 (35) ◽  
pp. 1387-1394
Author(s):  
Gábor Bajzik ◽  
Anett Tóth ◽  
Tamás Donkó ◽  
Péter Kovács ◽  
Dávid Sipos ◽  
...  
Keyword(s):  
Image Quality ◽  
Effective Dose ◽  
Dose Reduction ◽  
Iterative Reconstruction ◽  
Chest Ct ◽  
Ct Scans ◽  
Rank Test ◽  
Dose Length Product ◽  
Contrast Enhanced ◽  
Significant Difference

Abstract: Introduction and aim: In case of imaging modalities using ionizing radiation, radiation exposure of the patients is a vital issue. It is important to survey the various dose-reducing techniques to achieve optimal radiation protection while keeping image quality on an optimal level. Method: We reprocessed 105 patients’ data prospectively between February and April 2017. The determination of the radiation dose was based on the effective dose, calculated by multiplying the dose-length product (DLP) and dose-conversation coefficient. In case of image quality we used signal-to-noise ratio (SNR) based on manual segmentation of region of interest (ROI). For statistical analysis, one sample t-test and Wilcoxon signed rank test were used. Results: Using iterative reconstruction, the effective dose was significantly lower (p<0.001) in both native and contrast-enhanced abdominal, contrast-enhanced chest CT scans and in the case of the total effective dose. At native and contrast-enhanced abdominal CT scans, the noise content of the images showed significantly lower (p<0.001) values for iterative reconstruction images. At contrast-enhanced chest CT scans there was no significant difference between the noise content of the images (p>0.05). Conclusion: Using iterative reconstruction, it was possible to achieve significant dose reduction. Since the noise content of the images was not significantly higher using the iterative reconstruction compared to the filtered back projection, further dose reduction can be achievable while preserving the optimal quality of the images. Orv Hetil. 2019; 160(35): 1387–1394.

Sign in / Sign up

Export Citation Format

Share Document