فهرست مطالب علی چاپاریان

The parameters of image quality depend on the radiation dose and the CT scanner type. This study aimed to simultaneously compare the image quality and the risk of carcinogenesis caused by radiation in the CT scan of the brain in different scanners.

The present descriptive-analytical cross-sectional study was conducted on 200 patients who had been referred to hospitals of Isfahan city including Kashani (Siemens (scanner 1) and Canon (scanner 2)), Al-Zahra (General Electric (scanner 3)), Isa bin Maryam (Neusoft (Scanner 4)) for brain CT scan. Organ doses and effective doses of patients were obtained with a calculating program, Impact dose, and risk of exposure-induced death (REID) values estimated by the PCXMC program. The image quality was evaluated by examining the parameters of image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR). To compare different scanners, the CNR to REID ratio was introduced as the C criterion.

The average values of REID for scanners 1 to 4 were obtained at 2.98, 4.46, 5.07, and 4.65 per 100,000 men and 3.22, 6.16, 6.53, and 6.26 per 100,000 women, respectively. The average CNR values for scanners 1 to 4 were 1.24, 1.05, 1.66 and 2.08, respectively. Scanners 1 and 2 had the highest and lowest C criteria, respectively.

The results of this study showed that the radiation dose and the risk caused by radiation in the brain CT scan test should always be evaluated considering the image quality parameters, and a scanner with a higher CNR to REID ratio is more suitable.

Hand radiographs are commonly used to evaluate bone maturity. So that the significant difference between the estimated bone age and the chronological age can indicate a developmental disorder. However, the manual evaluation of images is usually a time-consuming and observer-dependent process. Therefore, in this paper, an automatic method for the assessment of bone age using radiographs of children's hands is proposed.

In this fundamental-applied research, the collection of radiographic images of the Radiological Society of North America (RSNA) was used, and transfer learning methods were proposed. The input images were first pre-processed due to low quality. Then a pre-trained model based on DenseNet-121 was used to extract the discriminating spatial features.

Evaluations using five pre-trained models on the RSNA dataset showed that the DenseNet-121 model, after adjustment, could perform better than other models, with a mean absolute error of 9.8 months.

Skeletal maturity can be estimated with satisfactory accuracy using the DenseNet-121 model, and this method can help radiologists in quick and accurate measurement of bone age.

The increasing frequency of pediatric chest CT scans has raised concerns regarding the radiation-induced cancer risks. The aim of this study was to evaluate image quality, organ doses, effective dose, and radiation-induced cancer risk from pediatric chest CT scans.

This is a cross- sectional study that was conducted on 128 children under 15 years old (52 girls and 76 boys) who underwent non-contrast chest CT scans. Patients were classified into four age groups of ≤1, 1-5, 5-10, and 10-15 years old. ImpactDose software was used to calculate organ doses, and risk of exposure-induced death (REID) values were estimated according to the BEIR VII report. In addition, image quality criteria including image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were also investigated.

The mean values of REID in pediatric chest CT scans were 129.43 per 100,000 women and 49.59 per 100,000 men. REID values decreased with the increasing age of patients and were higher for girls than for boys. The SNR values for the descending aorta, subcutaneous fat, and back muscle were 3.14, 12.14, and 5.42, respectively. In addition, CNRaorto-fat and CNRmuscle-fat values were equal to 15.41 and 17.53, respectively.

Chest CT scan in pediatrics is related to an increased potential risk of cancer. Therefore, chest CT in children should only be requested if the diagnostic benefits outweigh the radiation-related risks.

The aim of this study was to evaluate the effects of the kV Assist technique on the radiation dose and image quality of coronary computed tomography angiography (CCTA).

In this retrospective case-control study, 179 patients with the mean age of 58.45±11.86 years, who had undergone CCTA test using the kv assist technique, were considered as the study group; and 141 patients with the mean age of 58.24±11.37 years, who had previously undergone CCTA with the usual 120 kV protocol, were considered as the control group. The two groups were compared in terms of image quality criteria including noise, contrast-to-noise ratio, signal-to-noise ratio, CT numbers of the left coronary artery, and left ventricular chamber, and radiation dose criteria including effective dose and carcinogenic risk.

The effective dose (5.05 ± 2.16 vs. 6.63 ± 3.04 mSv; P < 0.001) and overall risk of carcinogenesis (3.89 ± 1.63 vs. 5.11 ± 2.71 in 10,000 people; P < 0.001) reduced by about 23%in the study group compared to the control group. No significant differences were observed between the two groups in terms of noise, signal-to-noise ratio, and left coronary artery CT number (P > 0.050). Left ventricular chamber CT number and contrast to noise ratio were higher in the study group than the control group (P < 0.001).

Using the kV Assist technique can reduce the effective dose and the carcinogenic risk of CCTA without loss of image quality.

According to the radiation hormesis hypothesis, low-dose ionizing radiation is not only dangerous, but also can even reduce the number of cancers in the irradiated community. The aim of this study was to evaluate radiation hormesis in the field of radiology.

The search was conducted through Science Direct, Scopus, PubMed, EMBASE, Google Scholar, and Web of science databases using the keywords of Ionizing radiation, Dose response, Hormesis, Low-dose radiation, Radiology, Radiation worker, and Patient in the period of 1990-2019.

In the early stages of the search, 1230 studies were found in databases. Finally, by reviewing the titles and abstracts of the articles, there were 38 articles related to the research topic. After careful consideration, four main areas were categorized including genetics area with 14 articles, cell area with 16 articles, animal area with 2 articles, and human area with 6 articles.

The effect of radiation hormesis has been rejected in some studies and confirmed in some others; but has not been demonstrated in radiation conditions similar to those found in radiology for patients and radiation workers. To confirm or disapprove this dose response model, detailed studies should be performed on radiation conditions such as different radiological tests in terms of beam type, beam energy, dose, and radiation dose rate.

The aim of this study was to evaluate the influences of iterative model reconstruction (IMR) and hybrid-iterative reconstruction (HIR) techniques on quantitative and qualitative image analysis of 256-slice coronary computed tomography angiography (CCTA).

Sixty-one patients (30 men and 31 women with mean age of 60.68 ± 9.13 years) who had undergone CCTA by the 256-slice CT scanner were evaluated. The raw data were reconstructed using HIR and IMR algorithms. For objective assessment of image quality, parameters of noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were obtained for both reconstruction algorithms. For subjective assessment, two physician specialists evaluated image quality using a 5-point scale.

The mean image noise on HIR and IMR images was 32.74 ± 6.04 and 25.15 ± 3.59, respectively. In IMR, the CNR method (28.81 ± 5.13) was significantly better than HIR method (23.06 ± 5.03) (P < 0.001). However, the HIR method (4.62 ± 0.39) was higher than the IMR method (4.48 ± 0.45) in terms of qualitative or subjective criteria (P < 0.001).

 The IMR method can improve quantitative criteria of image, reduce noise, and increase SNR and CNR of images better than HIR method. However, the images which reconstructed by HIR were superior to IMR in terms of qualitative criteria.

 The aim of this study was to evaluate the impact of using adaptive statistical iterative reconstruction (ASiR) method on image quality and reduction of organ doses, effective dose, and carcinogenesis risk from coronary computed tomography angiography (CCTA) in 64-slice CT scan.

 This cross-sectional study was performed on two groups of patients. The first group consisted of 185 patients (90 women and 95 men; mean age: 55.65 ± 14.77 years) who underwent CCTA with the conventional filter back projection (FBP) reconstruction. The second group consisted of 172 patients (80 women and 92 men; mean age: 58.59 ± 11.22 years) who were tested using ASiR reconstruction. Organ doses, effective dose, and carcinogenic risk were compared between the groups. Moreover, image quality criteria including noise, contrast-to-noise ratio, signal-to-noise ratio, CT numbers of the left coronary artery, and left ventricle were compared between the groups.

 There were at least 40% reduction in the effective dose (11.94 ± 5.64 vs. 20.38 ± 6.84 mSv; P < 0.001) and risk of carcinogenesis (8.97 ± 4.71 vs. 16.09 ± 8.42 in 10,000 people; P < 0.001) between the FBP and AsiR methods. No significant differences were observed between image quality parameters in the two reconstruction methods (P > 0.050).

 The application of ASiR method compared to conventional FBP method can reduce the dose of organs, the effective dose, and the carcinogenic risk of CCTA without compromising the image quality.

Upgrading analog X-ray systems to digital systems will greatly reduce costs, but there are conflicting opinions on this subject. Therefore, the purpose of this study was to compare image quality and radiation dose in different upgraded analog radiography systems with a digital radiography system.

Image quality and radiation dose of five upgraded analog radiography systems were compared with a digital radiography system using the Contrast Detail Radiography (CDRAD) phantom. Quality of images were independently evaluated on a workstation using a quantitative factor Inverse image quality figure (IQFinv) by three observers. Variations of IQFinv values were compared as a function of the Incident Air Kerma (IAK) parameter for different radiographic systems.

In a fixed IAK (1000 micrograms), the highest IQFinv was for upgraded analog radiography system number 4 (4.97) and the lowest IQFinv was for upgraded analog radiography system number 1 (3.61) (P = 0.001). The quality of images obtained with the upgraded analog radiography systems number 4 and 5 were better than ones of digital radiography.

If upgraded analog radiography systems can produce high quality images with low radiation dose compared to digital radiographic systems, the imaging departments is not needed to be spend a lot of money for replacing them with digital radiography systems.

Radiographers must be aware of the physical principles and capabilities of digital radiography systems in order to reduce radiation doses, and improve image quality. The aim of this study was to evaluate the knowledge of radiographers in occupied radiology centers in Isfahan City, Iran, regarding digital radiography systems. This descriptive-analytic study was carried out using a researcher-made valid and reliable questionnaire. The questionnaire included questions about demographic characteristics (age, gender, educational, and work experience), as well as questions about knowledge about radiation protection and physical principles of digital radiography systems. The questionnaires were distributed among 400 radiographers. The participation rate of radiographers was 57.5%. The average score of the general level of awareness among the radiographers was 40.29 ± 11.88 from 100, and in terms of radiation protection and physical principles of digital radiography systems, were 36.04 ± 16.88 and 44.54 ± 14.52 from 100, respectively. The level of general awareness as well as the level of knowledge about the physical principles had an inverse and weak relationship with the age and work experience of the radiographers (P < 0.05). More than 77 percent of the radiographers expressed their desire to participate in digital radiography courses. Awareness of radiographers about radiation protection and physical principles of digital radiography systems was at a low level. Therefore, with the development and deployment of digital radiology systems, the radiographers should be trained about these systems. Conducting such training classes can reduce radiation dose to patients, and reduce the risks of ionizing radiation.

Ionizing radiation used in computed tomography (CT) has a carcinogenic risk. The aim of this study was to evaluate the justification of CT scan requests by physicians in Kashani hospital, Isfahan, Iran.
Patient's data including the gender, age, type of CT scan, the cause of the request, the specialty of the requesting physician, and the test report were collected. The percentage of positive or abnormal cases for each test was obtained based on radiologist reports. The percentage of positive cases was also determined in term of the specialty of the requesting physicians.
Findings: The data of 888 patients were analyzed. The number of CT scans of the brain, abdomen, chest, spine, facial bones, pelvis, upper limbs, and lower limbs was 601, 13, 31, 76, 53, 29, 19, and 66, respectively. The lowest and highest percentages of positive results were related to brain (18.64%) and upper extremity (36.84%) CT scan, respectively. The highest percentage of normal results was related to patients referred to the CT scan by general practitioners, general surgeons, and emergency medicine specialists.
Totally, in all tests, 78.38% of the reports were normal, and less than 22% of the tests were indicative of pathological cases. Therefore, it is necessary to reduce the requests without indication to reduce the radiation dose of the community. The knowledge of the physicians about the suitable justification of the CT scan tests should be increased based on clinical guidelines, as well.

Ionizing radiation has long-term risks, especially cancer. Since physicians request radiological examinations for patients, they need to be aware of its benefit and also risks. The aim of this study was to assess the overall knowledge of physicians in Yazd province about the radiation risks associated with diagnostic imaging procedures. In this descriptive study a questionnaire containing 25 questions was used to evaluate physicians’ knowledge of radiation doses received from radiological procedures and risks of cancer from diagnostic imaging. Their demographics such as age, sex, specialty and experience (years of practice) was also asked. Normality of data distribution was assessed using the Shapiro–Wilks test and the Kolmogorov–Smirnov test. A t-test was used for continuous variables and comparison of mean differences in scores for dichotomous variables. Spearman's correlation coefficient was carried out to look for any relationship between variables of age and experience with the knowledge of the physicians. The overall mean knowledge score was 14 ± 3.15 out of 25 questions, or 56% ± 12.6%, and the scores ranged from 11.5% to 81%. The total mean score did not correlate with age and experience, but there was a significant difference (P value= 0.001) between men and women and also among the two main respondent groups, general practitioners and specialists (P value= 0.012). Physicians’ knowledge about detrimental effects of radiation including both deterministic and stochastic effects was very weak. The awareness of physicians about radiation is generally inadequate. Adequate training to practicing physicians about risks of radiological examinations seems needed, and revision of the curriculum of medical students in this area is recommended.

Pregnant women are sometimes exposed to ionizing radiation in radiology examinations for various reasons. In such cases, the radiation dose to the conceptus and subsequent risks should be estimated. The purpose of this study was the calculation and presentation of fetal dose and subsequent risks resulted from different X-ray examinations. An analytical simulation study was conducted and six common radiographies in different views and three types of special examinations were evaluated. The entrance skin exposure (ESE) was measured using a solid-state dosimeter. A Monte Carlo program was used in order to simulate different views of X-ray examinations and calculate the radiation doses received by the conceptus for every view of each examination. Then the risk of childhood cancer and small head size were calculated for different radiographies. The fetal doses and consequence risks of the small head size and childhood cancer for the radiographs of chest, skull, and sinuses were negligible but the risks of childhood cancer and small head size due to radiographies of abdomen, lumbar spine, and pelvis areas were ponderable. Results of this study can be used for the pregnant women radiographies management

Radiology tests are used to diagnose a variety of diseases. Performing such examinations has potential risks for patients and radiographers working in radiology departments. These risks can be minimized by compliance with safety practices. The aim of this study was to assess the knowledge، attitude، and practice of radiographers working in the radiology departments of Yazd about the new guidelines on radiation protection. A cross-sectional descriptive and analytic study was done using a 38 item questionnaire among all of 112 radiographers working in the radiology departments of Yazd Province. The data of completed questionnaire was analyzed by non-parametric tests and Spearman correlation coefficient using SPSS software. Participation rate for radiographers was 69. 6%. The average and standard deviation scores of knowledge، attitude and practice in the field of radiation protection were 46. 50±15. 30، 78. 33±12. 53، and 45. 90±16. 78، respectively. There was a significant inverse relationship between age and experience (years of practice) and knowledge of radiographers (P<0. 05). There was also a significant relationship between education and knowledge of radiographers. Results of this research showed that the amount of knowledge of radiographers in the field of radiation protection was decreased with increasing age and experience. Also، depending on the degree of their knowledge، there was a statistically significant difference in awareness. For solving this problem، the retraining courses contain new guidelines relating to radiation protection should be conducted.