Showing 6 results for Dose
Arezoo Imani, Fereidoun Mianji , Vahid Changizi, Seyyed Hossein Mousavie Anijdan , Reza Paydar,
Volume 11, Issue 3 (9-2017)
Abstract
Background and Aim: Estimation of radon density in underground centers is very important. Considering the use of high-energy medical accelerators, radiotherapy departments are usually located in underground floors. The aim of this study was to evaluate staff exposure to radon gas in these centers in Tehran in 2015-2016.
Materials and Methods: This is a descriptive, cross-sectional survey. In radiotherapy centers of Tehran, 32 radon gas diffusion chamber detectors were installed for a period of 3 months. After collecting the detectors, radon gas concentrations were calculated. The annual effective dose of personnel was evaluated using staff’s working hours per week.
Results: The minimum and maximum concentrations recorded in this study during one year were 22.14 and 398.52 Bq/m3, respectively, with an average of 87.01 ± 80.68 Bq/m3. Also, radiotherapy personnel’s annual effective dose was 0.34 ± 0.43 mSv per year with the minimum and maximum amounts of 0.02 and 2.35 mSv per year, respectively.
Conclusion: The results indicate that radon level in radiotherapy centers and also that the annual effective dose of personnel in these centers are permissible, and no special action is needed. However, if more attention is paid to certain factors such as air-conditioning, the amount of the gas can even be brought to less than this limit.
Vahid Changizi, Fereshteh Mohammadi , Ebrahiminia Ali,
Volume 11, Issue 5 (1-2018)
Abstract
Background and Aim: CT scan as a medical imaging modality delivers high radiation dose to the patients. Since eye and thyroid are two radiosensitive organs in this study, those effective doses were evaluated in brain CT scan. Using TLD as dosimeter.
Materials and Methods: This cross-sectional study was carried out in three selective hospitals in Rasht in September and October in year 2016.TLD was used as personal dosimeter. To measure the effective dose, TLDs were put on the patient’s eyes and thyroid and the mean effective dose was evaluated in brain CT scan. Results were analytical using SPSS software and Anova (P<0.05).
Results: The mean effective doses of eyes and thyroid in three hospitals with codes of H1, H2 and H3 were obtained as 2.66±2.04 mSv and 0.03±0.009 mSv, 1.80±1.11 mSv and 0.03±0.02 mSv, 1.94±0.95 mSv, 0.04±0.01 mSv, respectively. We found significant differences between effective doses of the eyes and thyroid in the three hospitals (p<0.05). Despite the difference in effective doses between right and left sides of eyes and thyroid, we didn't find any other significant differences.
Conclusion: The most important factor affecting patient radiation dose is the way CT scan examination is performed.
Vahid Changizi, Fereidoun Mianji, Fereshteh Ghaderbeygizad, Fereshteh Mohammadi,
Volume 12, Issue 5 (1-2019)
Abstract
Background and Aim: Coronary angiography (CA) is a diagnostic and therapeutic procedure for cardiac complexity, that has a high dose and high fluoroscopy time. The effective dose of eye lens as a radiosensitive organ in long-term exposure to CA must be evaluated.
Materials and Methods: A cross-sectional study was performed with Siemens under-bed machine in Imam Hossein Hospital of Mehran, Ilam Province of Iran, in January and February 2016. In this study, TLD was used as personal dosimeter. To measure the effective doses, TLD was put on the external side of cardiologists’ eyes under lead glasses. Data were analyzed by spss22 at a significant level (p<0.05).
Results: The mean fluoroscopy time in the radial route was 3.17±2.11 and in the femoral route was 12.65±6.97 minutes (p=0.003). The mean effective doses of cardiologists’ right and left eyes in radial and femoral angiography were 0.003, 0.005 (p=0.02) and 0.008, 0.011 (p=0.748), respectively. The mean effective dose of eye lens in the use of radial route was obtained less than that of femoral route. The mean effective doses in right and left eyes were not significantly different in the use of radial and femoral routes.
Conclusion: Fluoroscopy time and the distance of source are the main factors of more radiation on cardiologists.
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Volume 14, Issue 3 (7-2020)
Abstract
Background and Aim: Due to the increasing number of radiographic tests, TLD dosimeters can be used to measure the effective dose of critical organs in various radiographic tests. In this research, the progression of analogue to digital radiology devices, which facilitates and accelerates the performance of radiographs, especially emergency patients, was investigated, and then the effective dose of critical organs in digital radiographic devices was calculated using a thermoluminescence dosimeter.
Materials and Methods: In this cross-sectional study 29 thermoluminescence GR-200 dosimeters(LiF: Mg, Cu, P) were used first, the TLDs were calibrated by the Atomic Energy Organization of Tehran Protection Center, then using TLDs, equivalent doses were used in radiographic tests and finally, the effective dose of critical organs was calculated.
Results: Data were analyzed using Anova in SPSS software. The mean effective doses of critical organs were 0/034±0/0015 mSv for eyes(in skull radiography), 0/0063±0/0004 for thyroid(in cervical radiography), 0/0067±0/0009 for breast(in lung radiography) and 0/2010±0/0652 for ovarian(in abdominal radiography). We found significant differences between effective doses of thyroid and ovaries in common position(Postero Anterior)(p˂0.05). We found non-significant differences between effective doses of the eyes and breast in common position(AntroPosterior)(p˃0.05).
Conclusion: According to the results of this study, the effective dose of the patient in radiographic exames depends on the thickness of the target organ and the patient's position, which has a significant effect on the dose of radiation absorbed by the patient.
Zahra Danaei, Elahe Jazayeri Gharehbagh, Seyed Mahdi Hosseini Pooya, Samaneh Baradaran,
Volume 14, Issue 5 (1-2021)
Abstract
Background and Aim: In angiography, the lens of the eye may be exposed to radiation and cause cataracts. In Iran, at present, only a single film dosimeter is used under the lead-apron to evaluate individual doses. The aim of this study was to investigate the status of occupational radiation as well as the validity of measuring the dose of the whole body of individuals and eye lenses using a single film dosimeter.
Materials and Methods: In this study, the dose of the whole body and eye lenses were measured using a combination of film and thermoluminescence dosimeters for 35 employees of the angiography departments in three selected hospitals under the auspices of Tehran University of Medical Sciences(TUMS). To measure the eye lens dose, three thermoluminescence dosimeter pellets were used on the forehead, and left and right eyes; and to measure the whole body dose using the two-dosimetry method, a TLD card mounted on the chest and on the lead apron and a film dosimeter on the chest and under the lead apron were used.
Results: The angiography personnel's monthly dose mean of the eye lenses and the whole body were approximately 240.6±6.4 μSv and 120.3±3.3 μSv,
respectively(the corresponding amount for the annual dose is less than the levels recommended by international authorities). In addition, the dose ratio of film badge to whole body and eye lens was 0.35 and 0.51, with correlation coefficients of 0.97 and 0.5, respectively. Also, the ratio of eye lens dose to depth dose(TLD) on the lead apron was 1.18 with a correlation coefficient of 0.79.
Conclusion: Using a single film dosimter under the lead apron to estimate the dose of the whole body is almost accurate but this dosimeter alone is not suitable for the assessment of the lens dose of the eye; it is necessary to use an individual dosimeter on the lead apron.
Vahid Changizi, Maryam Mohammadi, Samaneh Baradaran, Mehran Taheri,
Volume 15, Issue 4 (10-2021)
Abstract
Background and Aim: On panoramic radiographs, sensitive organs, including the thyroid, are exposed to radiation. Thyroid cancer is one of the most common cancers in Iran. That is why, in this study the effective dose and risk of thyroid cancer were estimated on panoramic radiography.
Materials and Methods: Seventy GR200 thermoluminescence (TLD) dosimeters were used to estimate the absorbed dose of thyroid. The dosimeters were calibrated and placed on the patients’ necks during panoramic radiography. After dosimeters were read, the mean absorbed dose and effective thyroid dose were calculated in three groups with different radiation conditions. Lifetime Attributable Risk (LAR) of thyroid cancer was estimated using the model presented in the BEIR VII report. GraphPad Prism statistical software was used to analyze the data.
Results: The mean absorbed dose of thyroid lobes in groups M, L, XL (According to mandibular size) was estimated to be 0.116±0.01, 0.123±0.04 and 0.03±0.134 mg, respectively. The right thyroid lobe in group XL with absorption dose of 0.143±0.05 mg and the left lobe in group M with absorption dose of 0.106±0.03 mg had the highest and the lowest absorption doses, respectively. The difference between the absorbed doses of the right and left thyroid lobes in any of the three groups was not statistically significant. Thyroid absorption doses in these three groups were not statistically significant. The highest risk of thyroid cancer in the age range of 15-60 years was related to the age of 15, which was estimated to be 0.238 in women and 0.042 in men per 100,000 people.
Conclusion: In lower ages and among women, the risk of thyroid cancer is higher than that of men. Also, due to the impossibility of limiting thyroid radiation in panoramic radiography using lead thyroid collar that causes metal artifacts, we should reduce the number of panoramic radiographs as much as possible, especially at lower ages.
