جستجوی مقالات مرتبط با کلیدواژه « Effective dose » در نشریات گروه « پزشکی »

Computed tomography (CT) imaging has a large portion in the dose of patients from radiological procedures; therefore, accurate calculation of radiation risk estimation in this modality is inevitable. In this study, a method for determining the patient‑specific effective dose using the dose–length product (DLP) index in lung CT scan using Monte Carlo (MC) simulation is introduced.

EGSnrc/BEAMnrc MC code was used to simulate a CT scanner. The DOSxyznrc simulation code was used to simulate a specific voxelized phantom from the patient’s lungs and irradiate it according to X‑ray parameter of routing lung CT scan, and dose delivered to thorax organs was calculated. Three types of phantoms were simulated according to three different body habits (slim, standard, and fat patients) in two groups of men and women. A factor was used to convert the relative dose per particle in MC code to the absolute dose. The dose was calculated in all lung organs, and the effective dose was calculated for all three groups of patient body habits. DLP index and volume CT dose index (CTDIvol) were extracted from the patient’s dose report in the CT scanner. The DLP to effective dose conversion factor (k‑factor) for patients with different body habitus was calculated.

Lung radiation dose in slim, standard, and fat patients in men was 0.164, 0.103, and 0.078 mGy/mAs and in women was 0.164, 0.105, and 0.079 mGy/mAs, respectively. The k‑factor in the group of slim patients, especially in women, was higher than in other groups.

CT scan dose indexes for slim patients are reported to be underestimated in studies. The dose report in CT scan systems should be modified in proportion to the patient’s body habitus, to accurately estimate the radiation risk.

Inhaling radon is the most common way that humans are exposed to this radioactive gas. Radon can seep into buildings and homes, where it can accumulate to levels that can be harmful to human health. According to the World Health Organization, radon is the second most common cause of lung cancer.

The radon concentrations, effective dosage and lung dose were assessed in construction building materials of sand, cement, and bricks in Al-Shatra City, Dhi-Qar Governorate, Iraq using solid state nuclear track detector CR-39.

The average radon concentrations in sand were 92.766 ± 46.518 Bqm-3, while in bricks was 198.256 ± 87.64 Bqm-3 and cement was 69.897±46.903 Bqm-3. According to this study, there was difference in the concentrations of radon, and the largest amount was found in the bricks.  An annual effective dose was 2.34 mSvy-1, 4.99 mSvy-1 and 1.76 mSvy-1 for sand, bricks and cement, respectively. On the other hand, the lung dose was determined to be 3.71, 7.92 and 2.795 for sand, bricks and cement respectively.

The concentrations of radon gas in building materials were consistent with recommended by the International Commission on Radiological Protection (ICRP) 200-300 Bqm-3 except the bricks materials.

This study was performed to assess pediatric dose reference level for routine computed tomography (CT) examination (head, chest and abdomen-pelvic) along with its corresponding risks in Great Khorasan province, Iran.

For this purpose, different CT scan parameters of patients in 1-5, 6-10, and 11-15 years old were collected from 23 public hospitals. The total and main organ effective dose (ED),  and DLP was estimated by Impact Dose software for each age group. In addition, the cancer risk of each CT examination was calculated according to the BEIR VII model and ICRP 103 data with PCMX software.

The results of the estimated values of dosimetric quantities indicated that the range of changes of these quantities is very wide (3 to almost 10 times) even in a certain age group. In common CT scans, the highest value for the average dose received by the patient was 27.14 mGy for the brain, 11.41 mGy for the lung, and 9.88 mGy for the bladder, respectively. Also the highest amount of REID in men and women are caused by abdominal-pelvic and breast CT scan, respectively.

Although the values of studied quantities are not significantly different from similar reports, however, this does not reduce the important and necessity of the present study, as knowing the real amount dosimetric quantities in each area can help local authorities in revising and optimizing protocols to reduce patients’ dose.

Radon is a major source of natural radiation in water, soil, and air. Natural sources of radiation are major contributors to the radiation humans and other living beings receive. This cross-sectional study was conducted on drinking water sources of three cities and 18 villages of Roudan county in 2021. The measurement of radon concentration in the collected samples was performed using the RAD7 device. In the studied water sources, the highest and lowest radon concentrations were 11.00 ± 2.09 and 0.95 ± 0.23 kBq/m3, respectively. The average radon concentration was 4.98 ± 0.76 Bq/L which was lower than 11 Bq/L (the EPA level recommended for drinking water). The mean annual effective dose of radon, due to direct and continuous water intake for adults and children was 48.01 ± 11.56 and 65.86 ± 15.86 μSv/y, respectively. The results of this study showed that radon concentrations in two regions of Roudan county were higher than the allowed World Health Organization (WHO) concentration and people who normally use these resources for drinking during the year are exposed to abnormal radiation levels.

Radioactive contamination by uranium and its emissions, such as alpha particles, is considered one of the most critical issues affecting the human race and its existence. The study investigated the high ionization capacity number of alpha particles in whole blood samples from cancer patients because these particles have the most significant impact on the shape and function of living cells, modifying them into malignancies.
The TASLImage solid nuclear trace detector CR-39 was used to measure the effects of alpha emitters in the whole blood samples from 40 cancer patients for five types of cancer (breast, uterus, prostate, kidney, and colon) collected from a government hospital at Karbala/Iraq and compared with ten healthy samples. Moreover, the research investigated whether smoking and gender variation affect the outcomes.
The radon concentration in whole blood samples from patients and healthy individuals was significantly different (p< 0.05), and it was slightly higher in males with (22.82254±7.38794 Bq/m3). Women with colon cancer had higher blood levels of radon (32.13787±5.79261 Bq/m3) than men with the same malignancy (18.80531±5.63747 Bq/m3), regardless of gender. While the age factor had no noticeable impact, the smoking element had a considerable effect (p< 0.05).
All alpha levels were within the (ICRP) usual ranges. Women with colon cancer had the most significant alpha values. In contrast, men with the same disease had the lowest values despite cancer patients' blood levels being higher than those of the healthy group.

The same conversion factors (k-factors) of Single CT (SECT) are applied to estimate the Effective Dose (ED) in Dual Energy Computed Tomography (DECT). However, k-factors for different organs need independently validating for DECT, due to the different conditions in DECT.
This study aimed to calculate organ dose and k-factors in different imaging protocols (liver, chest, cardiac, and abdomen) for male and female phantoms.
This Monte Carlo Simulation study used Monte Carlo N-Particle (MCNP) code for modeling a Siemens Somatom Definition Flash dual-source CT scanner. The organ dose, dose length product, and k-factors were calculated for the Medical Internal Radiation Dose (MIRD) of male and female phantoms.
For the male phantom, the k-factors for the liver, chest, cardiac, and abdomen-pelvis imaging protocols are equal to 0.020, 0.012, 0.016, and 0.014 mSv.mGy−1cm−1, respectively. For the female phantom, the corresponding values are equal to 0.026, 0.023, 0.036, and 0.018, respectively. These values for DECT are different from those corresponding values for SECT, especially for the female phantom. 
The calculated k-factors for DECT can be used as reference values for the estimation of ED in DECT.

The purpose of this study was to establish of diagnostic reference level (DRL) and to compare radiation dose between single phase and unjustified double phase abdominopelvic CT imaging.
A total of 163 patients, 85 patients with single phase and 78 patients with unjustified double phase abdominopelvic CT scans, were included in this retrospective study. Volumetric CT dose index (CTDIvol) and dose length product (DLP) were obtained from the CT console. The third quartile of CTDIvol and DLP were determined for diagnostic reference level (DRL). Effective dose (E) and organ dose were obtained using CT-Expo software (version 2.2). Single phase and double phase scans were compared in terms of CTDIvol, DLP, size-specific dose estimate (SSDE), E and organ doses.
The institutional DRLs using CTDIvol and DLP for abdominopelvic CT were 9.8 mGy and 571 mGy.cm, respectively. The mean value of E was 5.4 ± 1.8 and 10.3 ± 3.4 for single phase and double phase imaging, respectively, resulting in 4.9 mSv excess dose per patient. Mean value of the DLP was 396.9 ± 142.7 and 759.0 ± 250.7 for single phase and double phase imaging, respectively. E was significantly higher in female compared to male (p < 0.05). Bladder has a highest lifetime attributed risk of cancer incidence among other organs. Also, the cancer risk incidence was higher for female than male.
The awareness of physicians about the correct indications of abdominopelvic CT should be increased by using associated reliable guidelines

Celosia leptostachya belongs to Amaranthaceae plant family. Its leaves are used traditionally in the treatment of conditions, such as convulsion, eye infection and most notably to cure snakebites. This study investigated the inhibiting effect of the extract of C. leptostachya leaves against cobra snake venom in mice.

We used 36 albino mice of mixed gender, weighing 20-25 g. They were divided into six groups of six rats each. Each rat was pre-treated with 0.4 mg/kg of cobra snake venom, and was subsequently given a graded dose of zero, 50, 100, 150, 200, or 250 mg/kg of the ethanol extract of C. leptostachya leaves. The animals were monitored for the survival rate. Various inhibition assays were performed to estimate the activities of acetyl cholinesterase, protease and adenosine triphosphatase of cobra venom, in the presence of 100-300 µg of the plant extract.

The extract inhibited the effects of cobra venom significantly after the intraperitoneal injection of the venom and extract at 20 minutes intervals. The results demonstrated that 100% of the mice survived if they received 100-250 mg/kg of the extract while only 83.3% survived with the extract at 50 mg/kg. The extract inhibited the venom’s acetyl cholinesterase, protease and adenosine triphosphatase. The inhibition occurred at higher percentages if the extract was given at 300 mg/kg. 

The plant extract significantly inhibited the snake venom, and its acetyl cholinesterase, protease and adenosine triphosphatase that mediated the venom’s toxicity.

Reports of natural radioactivity measurements from the environmentally sensitive regions of Papua New Guinea are few and far between. Radiological impacts owing to exposure to radionuclides which are naturally occurring from gold-mine regions in the Wau-Bulolo district of Morobe province in Papua New Guinea were appraised. Experimental locations were selected along the Bulolo River and its tributaries.

Ambient gamma levels were measured from the locations directly using a digital gamma dosimeter and the resulting indoor and outdoor annual effective doses were estimated. Measurements in the locations along with two control points each were made for the dose assessments. Selected radionuclides other than primordial were assessed in the samples of surface soil collected from sampling sites and control points. Gamma ray spectroscopy was used to estimate the activity levels of radionuclides in the soil samples collected from the sampling and control areas.

Presence of selected radionuclides were found in the soil samples along the river flowing through the mining area. All the samples analyzed showed very low activity levels thus having negligible effect on the background radiation level and human health.

With the widespread application of ionizing radiation in medical practice, concerns have been increased regarding the hazardous effects of radiation. Studies have demonstrated that some variables such as body dimensions affect the absorbed radiation dose. In this study, the association between Body Mass Index (BMI) and absorbed dose in Computed Tomography (CT) is investigated.

A total of 550 adult patients (age ≥ 15 years) were included in the study. The height and weight of the patients were recorded for BMI calculation. Dosimetry data were acquired from digital imaging and communications in medicine dose reports. The patients were categorized into five groups according to their BMI, the categorized information was then imported into ImPACT Dose software for calculation of Size-Specific Dose Estimate (SSDE) and organ and effective doses. The relationship between patient BMI and the effective dose was also determined.

A higher BMI contributed to increased radiation dose and SSDE in patients who had undergone chest or abdomen-pelvis CT examination (p < 0.05). 

The radiation dose is related to a patient’s BMI and rises with an increase in BMI. Accordingly, it is suggested that BMI and other variables, such as the type of scan and other body dimensions, which affect the radiation dose, can be used to estimate the radiation dose before performing CT. This estimation can be considered for the justification and optimization of CT examinations.

The increasing frequency of computed tomography (CT) scans for a range of purposes, particularly pediatrics, has raised concerns regarding the population's radiation exposure and subsequent chances of cancers. This study aimed to estimate the effective doses of pediatrics radiation and induced cancer risks from five most common CT scan procedures in Yazd Province, Iran.

Data of pediatric patients from four age groups of ≤1, 1-5, 5-10, and 10-15 years old were retrospectively collected from 6 educational institutions located in diverse areas of Yazd Province. For each participant, the effective doses and REID (risk of exposure-induced death) rate were estimated by Impact Dose and PCXMC software, respectively. Then, the findings were reported by categorizing the patients regarding their effective diameter.

The effective doses and REID values did not show any significant differences among the studied age groups. The highest mean of effective dose was recorded for the scan of abdomen-pelvis (average ± standard deviation, 5.24±3.19 mSv) followed by chest (3.76±2.28 mSv), brain (1.25±1.07 mSv), and sinus (0.65±0.4 mSv) examinations. The highest REID was documented for chest scan (490±314 excess deaths in one million scans) followed by abdomen-pelvis procedure (404±280).

The radiation doses delivered to the pediatric patients and the associated fatal cancer risk with common CT procedures were comparably in the same range of the previous studies. Our findings can represent an estimation of the radiation-induced risks of CT scans and can be used for extending the knowledge of clinicians and researchers.

This study aimed to determine entrance surface dose (ESD), calculate effective dose (ED), organ dose, and local dose  levels in three general hospitals of Khorramabad in common diagnostic radiographic examinations, including Chest and Skull.

Exposure parameters and data of 110 patients were collected during 6 months. In this study, three radiological devices including Shimadzu R-20, Mehran Teb DMT II and Varian Rad-8, were evaluated. Four radiographic views, including Chest posterior-anterior and lateral projections (PA/LAT), and Skull PA/LAT were also assessed. The index used for comparison and measurement of radiation dose was ESD measured using thermo luminescent dosimeter (TLD). In this study, a pc program for X-ray Monte Carlo (PCXMC) software was used to calculate the organs’ dose and effective dose.

The results obtained show that there is a significant relationship between mAs and kVp changes with ED and ESD values. ESD range in Chest PA, Chest LAT, Skull PA, and Skull LAT examinations were 0.1075-0.8844, 0.2059-2.2997, 0.0729-1.44, and 0.03478-1.15 mGy, respectively. In this study, the mean ESD estimated was lower than the diagnostic reference levels (DRLs) recommended by the National Radiological Protection Board (NRPB), the Commission of Europian Communities (CEC), and International Atomic Energy Agency (IAEA), but the ED calculated was relatively higher than other studies.

A combination of experimental and simulation methods usually makes the accuracy of the dose estimates more reliable. The mean ESD estimated in this study is lower than the DRL published by NRPB, CEC, and IAEA. Also the published ED is almost more than other studies. The results of this study are used to optimize the dose level of patients.

Approximation of radiation risks in computed tomography (CT) requires knowledge of specific organ doses. A Rando phantom and thermoluminescent dosimeters (TLDs) provide a proxy for in-vivo measurements. In this study, measured chest CT doses were used to calculate dose length product (DLP), a dosimetric needed for estimation of effective dose (E).

Ninety-five calibrated TLDs embedded at peripheral and central positions of Rando phantom chest slice measured chest CT dose during imaging using Phillips Brilliance 64-slice CT scanner. Three measurements were conducted each with new TLDs. Irradiated TLDs were read with a Harshaw TLD reader (Model 3500). One-way ANOVA test verified statistical significance of TLD measurements. TLD doses were used to calculate chest CT dose given as dose length product (DLP), a product of chest slice CT dose measured by volumetric CT dose index (CTDIv) multiplied by scan length. Consequently, E was calculated as the product of DLP and k, an adult chest conversion factor published by International Commission on Radiological Protection Publication 103.

  Differences in mean TLDs measurements were statistically significant (p=0.032). The mean chest slice peripheral and center doses were 3.61 ± 0.6 and 4.60 ± 0.31 mGy respectively. Adult chest CT dose was 178.8 ± 15 mGy. E was estimated as 2.5 ± 0.21 mSv. It is than the range (5.6 – 9.3 mSv) found in literature.

E relates radiation exposure to stochastic effects. The estimated value (E = 2.5±0.21 mSv), reveals that chest CT protocol used was optimized.

Radiation gives tremendous benefit to mankind but unnecessary radiation may pose harm to worker and public. The purpose of the studyis to continuous indoor radiation monitoring of Atomic Energy Centre Dhaka (AECD) campus to minimize the radiological risk on worker and public health in and around the campus.

Continuous indoor radiation monitoring was conducted in the AECD campus from November 2018-April 2019 using the Thermoluminescent dosimeters. The excess life-time cancer risk on workerand public health were estimated based on the continuous indoor radiation monitoring data.

The annual effective doses to the worker and public from indoor radiation were ranged from 0.28±0.11 mSv to 0.67±0.25 mSv and the mean wasfound to be 0.43±0.10 mSv. The excess life-time cancer risk (ELCR) on the radiation worker & public health were estimated based on the annual effective dose and ranged from 1.13 Χ 10-3 to 2.65 Χ 10-3 with an average of 1.72 Χ 10-3.The average annual effective dose and ELCR on worker and public health were lower than those of the worldwide average values.

The radiological hazard on worker and public health in and around the AECD campus is not significant because those values are lower than the recommended values of the international commission on radiological protection. Monitoring of these indoor places would help in keeping a record of safe working practices during the handling of the radioactive substances and radiation generating equipments in a radiological facility.

This review aimed to investigate the computed tomography (CT) imaging features of COVID-19.

Bilateral lung involvement (70%), peripheral distribution (67.5%), multifocal involvement (67.3%) and ground glass opacity (66.1%) were observed in most infected patients

Evaluation of the number of lobes involved in infected patients showed no abnormalities in 7.2% (85/1177) of the patients. Regarding the performance of RT-PCR and chest CT scan, the sensitivity of RT-PCR and chest CT imaging was estimated at 70% (925/1311) and 89% (6605/7396) upon admission, respectively; nevertheless, the sensitivity of CT imaging increased as the time from the symptom onset increased. The CT image acquisition parameters affecting image quality and patient dose were also discussed. Studies suggested that these factors should be adjusted according to the disease stage. Based on our findings, sensitivity was adequately high eight days after the onset of symptoms.

Therefore, there is no need for high-resolution chest CT scan after this interval. Using ImpactDose software, the mean effective doses were 4.38 and 5.71 mSv in male and female groups, respectively. The risk of cancer was 36% higher in females than males, as shown by PCXMC program.

Since human beings are constantly exposed to environmentalionizing radiations, the measurement of natural background radiations is of utmost importance. This cross-sectional, descriptive study aimed to measure the annual effective dose of natural background radiation in 93 schools in two districts of Hamadan, Iran in the winter, spring, and autumn of 2015-2016. Among the public schools in Hamadan, the schools located in district one with 1.41±0.079 mSv and district two with 0.955±0.04 mSv had the highest and lowest mean equivalent annual dose caused by natural radiation (γ rays) in a closed space, respectively. The mean equivalent annual dose caused by natural radiation in the closed space of all the public schools in districts one and two of Hamadan was estimated at 1.20±0.07 mSv as separated by geographical directions. In addition, the highest mean dose caused by natural gamma rays in the closed space of the school buildings constructed for more and less than 40 years was 1.42±0.22 and 1.42±0.15 mSv, respectively, and the rate of the effective annual dose of the public schools in Hamadan was determined to be 0.83 mSv as separated by district. The equivalent effective annual dose and risk of gamma ray cancer in the lifespan of the public school students in Hamadan was higher than the global average.

With the rapid development of medical imaging equipment and applications of radioactive substances in the diagnosis and treatment of diseases, the exposure of staff and patients to radiation doses becomes increasingly an alarming issue.

This study aimed at estimating the effective dose during radiologic and nuclear medicine examinations of patients, based on their administered dose activity. In parallel, the staff doses were also assessed using thermoluminescent dosimeters (TLDs). The staff members, specifically dealing with 99mTc, were also investigated for their eye lens dose exposure and radiogenic risk.

The mean of occupational annual dose for the whole body, Hp(10),  during the examinations of standard radiography, computed tomography (CT), interventional cardiology, and nuclear medicine were estimated to be 0.33, 0.31, 0.81, and 11.6 mSv, respectively. The annual exposure of eye lens dose, Hp(3), from 99mTc medicine examinations ranged from 4.9 to 11.8 mSv.

In this study, the Hp(3) for medical staff, at the nuclear medicine department, was evaluated by measuring the Hp(10). The doses reported in this study were interestingly found to be less than the annual dose limits recommended by the concerned international organizations.

In conventional X-ray examinations, patients are exposed to radiation. Biological hazards from radiation of any source is expressed as effective dose, and is measured in millisieverts (mSv). The purpose of this study was to assess and calculate the effective dose values for patients undergoing posteroanterior (PA) chest, abdomen, anteroposterior (AP) pelvis, and cervical spine X-ray examinations in general hospitals of Erbil city and compare it with those of other studies.

A total of 255 patients between 20-70 years of age participated in this work (85 per hospital). The patients’ characteristics included age, sex, examination type, projection posture, and exposure parameters captured by NOMEX Multimeter including tube potential and current-time product. The mean effective doses (EDs) of four different examinations (chest (PA), pelvis (AP), abdomen, and cervical spine) were measured using the Monte Carlo method and compared with those of other studies.

The mean EDs were calculated 1.04, 2.01, 3.12, and 3.22 mSv for chest (PA), pelvis (AP), abdomen, and cervical spine, respectively. All ED values in this study were higher than those of published studies. The aim of the study was to increase the awareness of the radiographer and patients undergoing conventional X-ray diagnostic radiology on the risk of ionizing radiation for radiological protection in Erbil hospitals.

The mean EDs were increased by an increase in the age; this may increase the probability of cancer incidence and heritable diseases. Hence, dose optimization is required due to more probable incidence of cancer when compared to other studies.

This study aimed to estimate and compare the absorbed dose, lifetime cancer risk and mortalities due to cone-beam computed tomography (CBCT) and panoramic examinations on patients.

The exposure factors were applied to 332 patients in two age groups (6-10, and ˃18-year-old). The dose-area product (DAP) values were measured for CBCT and panoramic radiographies. Organ absorbed doses and effective doses were calculated based on the collected parameters applying PCXMC software. The risk of exposure-induced death (REID) and cancer risks were estimated by BEIR VII phase 2 model at different age groups and genders for the two dental radiography modalities.

Salivary glands was the largest contribution of the organ absorbed dose and effective dose in both CBCT and panoramic radiographies. The mean (±SD) REID values (per ten million) in CBCT were obtained at 35.6±5.2 for females and 29.01±1.8 for males, in the pediatric group, and were 31.1±2.2 for females and 25.71±2.02 for males in the adult group for all cancers. In addition, these values for panoramic radiography were 10.2±1.2 and 6.61±1.2 for women and men, respectively, in the pediatric group, and were 5.3±1.06 and 3.01±1.12 in the adult group. The mean REID values were higher significantly in CBCT compared to panoramic, and also in the pediatric than adult groups (p˂0.05).

CBCT had a significantly higher level of radiation risks compared to panoramic radiography. Therefore, clinicians should request CBCT examinations by considering their determents and benefits.