Showing 8 results for Changizi
V Changizi , M Mireshgholah , Sj Ghazi Mirsaeid ,
Volume 1, Issue 1 (9 2007)
Abstract
Background and aim:Blood cells have an important role in human healthy, so their shapes and numbers are defined as human healthy indexes. These factors are measured by cell counter machines. Presenting a high quality report according to cell counters output is dependant on their operational accuracy. Therefore it was necessary to do a study on quality control of blood cell counter machines in selective medical laboratories of Tehran.
Method of study:This study was an experimental type in selective medical laboratories of Tehran. "Brittin method" was used as a general method for 6 selective machines over WBC, RBC, Hb, HCT, MCV, MCH and MCHC. In this method red blood cells index stability with EDTA, in 4oC for 24 hour is assessed. Data was collected before and after quality controls and finally data analysis was done by T- student (paired samples T test) method and SPSS software.
Results:Using Brittin method showed all selective machines had significant differences before and after quality control in one or more quality factors (P-value< 0.05).
Conclusion:Quality control can show inaccuracy in cell counter machines output and finally inaccuracy over patient blood tests. By this subject we can have high quality diagnosis. This study showed parameters producing errors are error in sample volume, biological factors, error in concentration and using bad solutions.
Farahnaz Azarakhsh, Vahid Changizi,
Volume 10, Issue 3 (7-2016)
Abstract
Background and Aim: Brain tumors have remained as a significant cause of morbidity and mortality and are often refractory to treatment. The grading of brain tumor has an important implication in clinical management. Currently, magnetic resonance spectroscopy (MRS) is an important dimension in evaluating metabolites and grading brain tumors. The aim of this study is to evaluate metabolites in brain tumors and grading brain gliomas using HMRS (proton magnetic resonance spectroscopy).
Materials and Methods: Studies were performed using single voxel MRS, at a field strength of 3Tesla and pulse sequence using point resolved single volume spectroscopy (PRESS) with repetition time (TR) 1000-6000ms and echo time (TE) 36-136ms, and distinguished metabolites including Choline (Cho), Creatin (Cr), and N-acetyl aspartate (NAA) were detected.
Results: Thirty-seven cases (17 males and 20 females) had data which passed quality control. The patients’ age ranged from 7 to 81 years with a mean of 41.46±2.78. MRS data were processed using SYNGO software in terms of mean spectra and metabolite concentrations which were compared using minitab and SPSS. Significant differences were found in concentrations of key metabolites, and Cho/NAA and Cho/Cr ratios using t-test with a significance level (α≤0.05). In the assessment of age rate and tumor grading, the malignancies of brain tumors did not correlate with patients’ age and sex.
Conclusion: MRS can detect subtle differences between low-grade brain tumors in children and should form part of the clinical assessment of these tumors.
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, Hossein Sadeghi, Maryam Alizadeh, Atefeh Aghaei, Mohsen Yazdanmehr,
Volume 12, Issue 3 (Aug & Sep 2018)
Abstract
Background and Aim: Today, OSL (Optically Stimulated Luminescence) dosimetry system based on optical stimulation, includes systems that can meet many requirements for radiation protection in the field of medicine and space. The Calcium Sulfide (CaS) is one of the earth's alkaline sulfide materials which can be used as a detector in this system. In this research, some of the dosimetry properties of CaS doped with Cerium, (Ce), and Samarium, (Sm) elements were investigated as OSL dosimeter sensor.
Materials and Methods: First, attenuation of x-rays through the sensors were analyzed and the absorbed dose rate was evaluated using MCNP code. After calcium sulfide tablets were fabricated and their concentration optimized, the maximum waiting time prior to readout was obtained. In addition, the repeatability and linear response of the detector were determined as a function of CaS concentration.
Results: Eight minutes after radiation exposure of detectors, the detection output signals became stable. This stability was monitored for at least 30 minutes after irradiation. The repeatability in measurements was observed within the dose ranges of 100 to 860 mGy. The dosimeter response was observed linear over this dose ranges.
Conclusion: According to the above-observed results and statistical evaluations, one can conclude that the CaS:Ce,Sm crystal is a proper sensor for OSL dosimeter systems in medicine and space studies.
Vahid Changizi, Fereidoun Mianji, Fereshteh Ghaderbeygizad, Fereshteh Mohammadi,
Volume 12, Issue 5 (Dec & Jan 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.
Vahid Changizi, Mohammad Reza Zare, Sahel Kasiri,
Volume 13, Issue 5 (Dec & Jan 2020)
Abstract
Background and Aim: Due to the presence of ionizing radiation sources in the environment and their potential to enter the food chain, the natural radiation in the rice product of Mahmoud Abadu residents of this area should be evaluated.
Materials and Methods: Using standard sampling methods, the number of sampling points and locations (about 10 points) was determined. After recording the geographical location of the sites, 2 kg of soil and 2 kg of rice were removed and 20 samples were coded. 950 g of soil and rice were milled and transferred to standard Marinelli dishes with 50 mesh. The samples were completely sealed and after about one month, they were visualized with ultra-pure germanium detectors (HPGe). Subsequently, specific radionuclide radiosensitivity in soil and rice soil samples, radionuclide transfer factors from soil to rice, annual effective dose and risk of cancer due to rice consumption were measured.
Results: Effective total dose of nuclei studied in #value, lifetime cancer risk of U238 from #value to 0.00019, Ra226 from #value to 0.00008, U235 # value, Th232 from #value to 0.00027, K40 From 0.00014 to 0.00082 and finally for zero cesium.
Conclusion: There is no harmful effect on the people of the region regarding the radionuclides of rice.
Vahid Changizi, Maryam Mohammadi, Samaneh Baradaran, Mehran Taheri,
Volume 15, Issue 4 (oct & Nov 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.
