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.

scholarly journals Patients Radiation Risks from Computed Tomography Lymphography

2020 ◽  
Vol 10 ◽  
pp. 46 ◽  
Author(s):  
Abdullah Almujally ◽  
Abdelmoneim Sulieman ◽  
Fabrizio Calliada
Keyword(s):  
Computed Tomography ◽  
Clinical Indication ◽  
Radiological Protection ◽  
Organ Doses ◽  
Radiation Induced Cancer ◽  
Radiation Induced ◽  
Patient Doses ◽  
Effective Doses ◽  
The Mean ◽  
Ct Lymphography

Objectives: This study aims to first measure patient doses during computed tomography (CT) chest, abdomen, and extremities procedures for evaluation lymphedema, and second to estimate the radiation dose-related risks during the procedures. Material and Methods: Radiation effective doses from CT lymphography procedures quantified using CT machines from different vendors. After the calibration of CT systems, the data collected for a total of 28 CT lymphography procedures. Effective and organ doses extrapolated using national radiological protection software based on Monte Carlo simulation. Results: The mean patient doses for chest and abdomen procedures in term of CTDIvol (mGy) and DLP (mGy.cm) are 10.0 ± 3 and 425 ± 222 and 24 ± 12 and 1118 ± 812 for CT 128 and CT 16 slice, respectively. The mean DLP (mGy.cm) for extremities was 320 ± 140 and 424 ± 212 for CT 128 and CT 16 slice, in that order. Conclusion: Patients’ dose showed significant differences due to variation in the scan length and clinical indication. Organs lay in the primary beam received high radiation doses especially in the chest region which increases the probability of radiation-induced cancer. The current patient’s doses are higher compared to the previous studies.

scholarly journals Digital orthodontic radiographic set versus cone-beam computed tomography: an evaluation of the effective dose

2016 ◽  
Vol 21 (4) ◽  
pp. 66-72 ◽  
Author(s):  
Lillian Atsumi Simabuguro Chinem ◽  
Beatriz de Souza Vilella ◽  
Cláudia Lúcia de Pinho Maurício ◽  
Lucia Viviana Canevaro ◽  
Luiz Fernando Deluiz ◽  
...  
Keyword(s):  
Computed Tomography ◽  
New York ◽  
Effective Dose ◽  
Cone Beam Computed Tomography ◽  
Cone Beam ◽  
Radiological Protection ◽  
Anthropomorphic Phantom ◽  
Thermoluminescent Dosimeters ◽  
Optimization Principle ◽  
Effective Doses

ABSTRACT Objective: The aim of this study was to compare the equivalent and effective doses of different digital radiographic methods (panoramic, lateral cephalometric and periapical) with cone-beam computed tomography (CBCT). Methods: Precalibrated thermoluminescent dosimeters were placed at 24 locations in an anthropomorphic phantom (Alderson Rando Phantom, Alderson Research Laboratories, New York, NY, USA), representing a medium sized adult. The following devices were tested: Heliodent Plus (Sirona Dental Systems, Bernsheim, Germany), Orthophos XG 5 (Sirona Dental Systems, Bernsheim, Germany) and i-CAT (Imaging Sciences International, Hatfield, PA, USA). The equivalent doses and effective doses were calculated considering the recommendations of the International Commission of Radiological Protection (ICRP) issued in 1990 and 2007. Results: Although the effective dose of the radiographic set corresponded to 17.5% (ICRP 1990) and 47.2% (ICRP 2007) of the CBCT dose, the equivalent doses of skin, bone surface and muscle obtained by the radiographic set were higher when compared to CBCT. However, in some areas, the radiation produced by the orthodontic set was higher due to the complete periapical examination. Conclusion: Considering the optimization principle of radiation protection, i-CAT tomography should be used only in specific and justified circumstances. Additionally, following the ALARA principle, single periapical radiographies covering restricted areas are more suitable than the complete periapical examination.

Epidemiological studies of CT scans and cancer risk: the state of the science

2021 ◽  
Vol 94 (1126) ◽  
pp. 20210471 ◽  
Author(s):  
Amy Berrington de Gonzalez ◽  
Elisa Pasqual ◽  
Lene Veiga
Keyword(s):  
Brain Tumors ◽  
Effective Dose ◽  
Dose Response ◽  
Public Health Problem ◽  
Epidemiological Studies ◽  
Ct Scans ◽  
Medical Record Linkage ◽  
Cancer Risks ◽  
Organ Doses ◽  
Study Methodology

20 years ago, 3 manuscripts describing doses and potential cancer risks from CT scans in children raised awareness of a growing public health problem. We reviewed the epidemiological studies that were initiated in response to these concerns that assessed cancer risks from CT scans using medical record linkage. We evaluated the study methodology and findings and provide recommendations for optimal study design for new efforts. We identified 17 eligible studies; 13 with published risk estimates, and 4 in progress. There was wide variability in the study methodology, however, which made comparison of findings challenging. Key differences included whether the study focused on childhood or adulthood exposure, radiosensitive outcomes (e.g. leukemia, brain tumors) or all cancers, the exposure metrics (e.g. organ doses, effective dose or number of CTs) and control for biases (e.g. latency and exclusion periods and confounding by indication). We were able to compare results for the subset of studies that evaluated leukemia or brain tumors. There were eight studies of leukemia risk in relation to red bone marrow (RBM) dose, effective dose or number of CTs; seven reported a positive dose–response, which was statistically significant (p < 0.05) in four studies. Six of the seven studies of brain tumors also found a positive dose–response and in five, this was statistically significant. Mean RBM dose ranged from 6 to 12 mGy and mean brain dose from 18 to 43 mGy. In a meta-analysis of the studies of childhood exposure the summary ERR/100 mGy was 1.78 (95%CI: 0.01–3.53) for leukemia/myelodisplastic syndrome (n = 5 studies) and 0.80 (95%CI: 0.48–1.12) for brain tumors (n = 4 studies) (p-heterogeneity >0.4). Confounding by cancer pre-disposing conditions was unlikely in these five studies of leukemia. The summary risk estimate for brain tumors could be over estimated, however, due to reverse causation. In conclusion, there is growing evidence from epidemiological data that CT scans can cause cancer. The absolute risks to individual patients are, however, likely to be small. Ongoing large multicenter cohorts and future pooling efforts will provide more precise risk quantification.

Radiation Dose to Patients and Personnel during Fluoroscopy at Percutaneous Renal Stone Extraction

1989 ◽  
Vol 30 (2) ◽  
pp. 201-206 ◽  
Author(s):  
K. Geterud ◽  
A. Larsson ◽  
S. Mattsson
Keyword(s):  
Radiation Dose ◽  
Effective Dose ◽  
Renal Stone ◽  
Absorbed Dose ◽  
Effective Dose Equivalent ◽  
Dose Equivalent ◽  
Organ Doses ◽  
The Mean ◽  
Total Effective Dose Equivalent ◽  
Total Effective Dose

The radiation dose to patients and personnel was estimated during 11 percutaneous renal stone extractions. For the patients the energy imparted, the mean absorbed dose to various organs, and the effective dose equivalent were estimated. For different personnel categories some organ doses and the effective dose equivalent were also estimated. Large differences in the radiation dose between patients were observed. The mean effective dose equivalent to the patient was 4.2 (range 0.6–8.3) mSv, and the energy imparted 285 (range 50–500) mJ. These figures are comparable to those reported for routine colon examination and urography. For the personnel there were also large differences between individuals and categories. The highest radiation dose was received by the radiologist. It was estimated that a radiologist who performs 150 percutaneous renal stone extractions per year will receive a yearly contribution to his/her effective dose equivalent of 2.4 mSv. Even when the contribution from other diagnostic and interventional radiologic procedures is added, the total effective dose equivalent hardly exceeds 5 mSv or 1/10 of the present dose limit for persons engaged in radiologic work. For the hands of the radiologist there is a risk of doses closer to the present limit for single organs or tissues of 500 mSv/year.

RESULTS OF CZECH NATIONAL STUDY OF RADIATION EXPOSURE FROM RADIOTHERAPY OF NON-MALIGNANT DISEASES, IN PARTICULAR OF HEEL SPURS

2019 ◽  
Vol 186 (2-3) ◽  
pp. 386-390
Author(s):  
V Dufek ◽  
H Zackova ◽  
L Kotik ◽  
I Horakova
Keyword(s):  
Czech Republic ◽  
Clinical Practice ◽  
Radiation Exposure ◽  
Effective Dose ◽  
National Study ◽  
Malignant Diseases ◽  
Organ Doses ◽  
The Czech Republic ◽  
X Ray ◽  
Effective Doses

Abstract About 26 000 patients are treated per year with radiotherapy for non-malignant diseases in the Czech Republic. Approximately 75% of them are treated on X-ray therapy units and most of these patients undergo radiotherapy of heel spurs. The evaluation of radiation exposure of these patients was based on measured organ doses and on data from clinical practice. Collective effective doses for particular diagnoses were calculated in order to compare doses resulting from different diagnoses treated on X-ray therapy units. The collective effective dose from radiotherapy of heel spurs in the Czech Republic in 2013 was evaluated to 77 manSv. It represents 25.6% of the total collective effective dose for all diagnoses of radiotherapy for non-malignant diseases treated on X-ray therapy units.

scholarly journals Effective dose in medicine

2020 ◽  
Vol 49 (1_suppl) ◽  
pp. 126-140
Author(s):  
C.J. Martin
Keyword(s):  
Nuclear Medicine ◽  
Effective Dose ◽  
Imaging Techniques ◽  
Radiological Protection ◽  
Medical Procedures ◽  
Patient Referral ◽  
Similar Dose ◽  
Effective Doses ◽  
Public Exposure ◽  
Made In

The International Commission on Radiological Protection (ICRP) developed effective dose as a quantity related to risk for occupational and public exposure. There was a need for a similar dose quantity linked to risk for making everyday decisions relating to medical procedures. Coefficients were developed to enable the calculation of doses to organs and tissues, and effective doses for procedures in nuclear medicine and radiology during the 1980s and 1990s. Effective dose has provided a valuable tool that is now used in the establishment of guidelines for patient referral and justification of procedures, choice of appropriate imaging techniques, and providing dose data on potential exposure of volunteers for research studies, all of which require the benefits from the procedure to be weighed against the risks. However, the approximations made in the derivation of effective dose are often forgotten, and the uncertainties in calculations of risks are discussed. An ICRP report on protection dose quantities has been prepared that provides more information on the application of effective dose, and concludes that effective dose can be used as an approximate measure of possible risk. A discussion of the way in which it should be used is given here, with applications for which it is considered suitable. Approaches to the evaluation of risk and methods for conveying information on risk are also discussed.

scholarly journals Abdominal Pediatric Cancer Surveillance Using Serial Computed Tomography: Evaluation of Organ Absorbed Dose and Effective Dose

2011 ◽  
Vol 38 (1) ◽  
pp. 128-135 ◽  
Author(s):  
Diana Lam ◽  
Sandra L. Wootton-Gorges ◽  
John P. McGahan ◽  
Robin Stern ◽  
John M. Boone
Keyword(s):  
Computed Tomography ◽  
Effective Dose ◽  
Pediatric Cancer ◽  
Absorbed Dose ◽  
Cancer Surveillance

THE INFLUENCE OF THE EQUILIBRIUM FACTOR ON THE ESTIMATED ANNUAL EFFECTIVE DOSE FROM INHALED RADON DECAY PRODUCTS IN SELECTED WORKPLACES

2020 ◽  
Vol 191 (2) ◽  
pp. 188-191
Author(s):  
Petr P S Otahal ◽  
Ivo Burian ◽  
Eliska Fialova ◽  
Josef Vosahlik
Keyword(s):  
Effective Dose ◽  
Activity Concentration ◽  
Annual Effective Dose ◽  
Radiological Protection ◽  
Equilibrium Factor ◽  
Decay Products ◽  
Water Treatment Plants ◽  
Radon Decay ◽  
Effective Doses ◽  
Dose Coefficients

Abstract Measurements of activity concentration of radon gas and radon decay products were carried out in several workplaces including schools, radium spas, swimming pools, water treatment plants, caves and former mines. Based on these measurements, annual effective doses to workers were estimated and values of the equilibrium factor, F, were calculated. This paper describes the different approaches used to estimate the annual effective dose based on the dose coefficients recommended by the International Commission on Radiological Protection. Using the measured F values as opposed to the default F value of 0.4 changed the doses by about 5–95% depending mainly upon the ventilation conditions of the workplace.

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.

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