Pediatric dose assessment in common CT examination towards establishment of related regional DRL in Mazandaran, Iran

Background: Computed Tomography [CT] is main contributor of population dose from diagnostic X-ray examinations. Children are more radiosensitive than adults, thus optimization of CT examination in these patients is essential. The purpose of this study was to evaluate dose delivered to pediatric patients' undergoing CT examination of the common examinations and also establishing local Diagnostic Reference Levels [DRLs]. Materials and Methods: Questionnaires were designed for data collection at seven public hospitals and information about patient, protocol and CT system were recorded during 2013 and 2014. Dose measurement was performed in four age groups: 0-1, 1-5, 5-10 and 10-15 years old and two CT dose quantity including CTDIw and DLP were calculated. Results: Values of 40, 48, 59.5, 59.5 mGy; 16.9, 16.9, 17.14, 17.14 mGy; 17, 17, 17, 17 mGy; 17, 17, 19.2, 19.2 mGy in terms of CTDIw and 448, 538, 758, 758 mGy cm; 129, 129, 154, 167 mGy cm; 184, 225, 306, 315 mGy cm; 289, 408, 595, 670 mGy cm in terms of DLP as regional DRL for brain, sinus, chest, abdomen and pelvic examinations were obtained respectively. Conclusion: The variations in dose of some examination were considerable. As the role and usage of CT technology continues to expand, it is important that all practitioners adapt optimized protocols, especially for pediatrics scanning, following proposed reference levels

HVL evaluation of orthovoltage X-ray machine using EGSnrc code of simulation

Making use of the orthovoltage machines in Radiotherapy, is one of the routine methods for the treatment of the superficial lesions. In this study, an important determinant of X-ray quality, the HVL [Half Value Layer], has been evaluated. The HVLs of a orthovoltage X-ray machine in 120 and 180 kVp are measured, using an empirical method, in which the HVLs are derived from the absorption curves. The measured HVLs are compared with calculated [Monte Carlo simulation] HVLs. Using the BEAMDP code of simulation, the output spectra are obtained and employed for the measurement of the HVLs. Comparing the calculated and measured HVL values, the results show that the highest and lowest differences between the two are 4.96% and 2.27%, respectively, which are, in fairly good agreement with those obtained in the former studies. This study shows that the EGSnrc simulation code is capable of being used for the extraction of the quality indices for the superficial X-ray radiotherapy machines. It seems that, the mentioned code, with the mentioned experimental method, can be employed as a routine clinical test tool for every superficial radiotherapy department

Estimation of external natural background gamma ray doses to the population of Caspian coastal provinces in North of Iran

The effect of natural background radiation on health is still controversial. However, it is clear that it depends on the dose received by the population. The estimation of external natural background gamma rays received by the population of Caspian coastal provinces in the northern part of Iran was the main goal of this study. Gamma rays was measured using calibrated radiation survey meter in 51 urban and rural health centers randomly to estimate the exposure to population [Total population=6888118 persons] in residential areas of Gilan, Mazandaran and Golestan [Total area 59240 Km2] as Caspian coastal provinces, North of Iran. Results showed that the average dose rate in the areas under study was about 60.37 +/- 14.88 nSv/h or 0.53 mSv/yr [Range 30 to 90 nSv/h or 0.26 to 0.79 mSv/yr]. The data from Ramsar was excluded from the estimation because of its very high natural background radiation [Max. 240 mSv/yr]. No significant difference was found among the doses of the provinces [P=0.237]. The external natural background gamma ray dose to the population of Caspian coastal provinces, North of Iran, was found to be almost equal to the average value in the world [0.5 mSv/yr]

Repeat analysis program in radiology departments in Mazandaran province-Iran. Impact on population radiation dose

The rejected films in radiography may be responsible for an unnecessary increase in the radiation dose to the population. The effective dose to population is a very important factor in estimation of stochastic risk in radiology. The main goal of this study was to determine the effective dose to members of the public due to rejected films in diagnostic radiology departments in the Northern Province Mazandaran- of Iran. A repeat analysis program was set in all radiology departments in Mazandaran province [population = 2976219 person] to determine the total number and type of rejected films. All repeat and discarded films were collected and separated into types according to the etiology leading to their being discarded. Considering technical data about various radiological procedures and using the standard dosimetry tables, the annual effective dose per caput as well as annual gonadal dose per caput due to image retake was estimated. The total number of rejected radiographs in one year period was 73857 [overall reject rate tilde 11.15%] which led to 34.91 micro Sv and 37.17 micro Gy as annual average effective dose to a member of the public and annual average gonadal dose per caput respectively. The main reason of retaking the images was improper exposure factors. The reject rate was in the middle range of similar values in other studies; whereas in the present study the main reason for rejection was improper exposure factors [67.11%], the main reason for radiography repeat film was different in various countries. Comparing to the estimated 2.4 mSv from natural background radiation, the average annual effective dose and annual average gonadal dose per caput due to repeat/retake films are negligible. However, reducing the reject films is economically rewarding. Further national studies are suggested

estimation of ratiation effective dose from diagnostic medical procedures in general population of Northern Iran

The risks of low-dose ionizing radiation from radiology and nuclear medicine are not clearly determined. Effective dose to population is a very important factor in risk estimation. The study aimed to determine the effective dose from diagnostic radiation medicine in a northern province of Iran. Data about various radiologic and nuclear medicine procedures were collected from all radiology and nuclear medicine departments in Mazandaran Province [population = 2,898,031]; and using the standard dosimetry tables, the total dose, dose per examination, and annual effective dose per capita as well as the annual gonadal dose per capita were estimated. 655,730 radiologic examinations in a year's period, lead to 1.45 mSv, 0.33 mSv and 0.31 mGy as average effective dose per examination, annual average effective dose to member of the public, and annual average gonadal dose per capita, respectively. The frequency of medical radiologic examinations was 2,262 examinations annually per 10,000 members of population. However, the total number of nuclear medicine examinations in the same period was 7074, with 4.37 mSv, 9.6 micro Sv and 9.8 micro Gy, as average effective dose per examination, annual average effective dose to member of the public and annual average gonadal dose per caput, respectively. The frequency of nuclear medicine examination was 24 examinations annually per 10,000 members of population. The average effective dose per examination was nearly similar to other studies. However, the average annual effective dose and annual average gonadal dose per capita were less than the similar values in other reports, which could be due to lesser number of radiation medicine examinations in the present study