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PURPOSE Evaluation of the organ dose in pediatric patients up to 15 years old and Estimation of lifetime attributable risk (LAR) of cancer incidence in pediatric computed tomography procedures. MATERIALS AND METHODS Data from 532 patients below 15 years old was collected and they were categorized into four age groups of

Background: Ionizing and non-ionizing radiation are widely used in the diagnosis and treatment of diseases. Considering the potential risks of radiation, radiation safety training courses are important for medical staff. Objective: The aim of this study was to investigate the effectiveness of one-day radiation safety training program in increasing the radiation safety knowledge of physicians. Methods: In this descriptive-analytical study, subjects were 12 physicians (6 general practitioners and 6 non-radiologist specialists) participated in the training program organized by Qazvin University of Medical Sciences in 2018. A researcher-made questionnaire was used for surveying physicians before and after the training. The mean and standard deviation of the scores were first calculated. Then, the pre- and post-test scores were compared using Wilcoxon signed-rank test, and the correlation of these scores with their age, gender, expertise area, and work experience was examined by Spearmanchr('39')s correlation test. Findings: The mean total scores of the physicians before and after training were 7.00±2.56 (ranged 3-11) and 11.92± 2.31 (ranged 8-15) out of 18, respectively. The radiation safety knowledge of physicians significantly increased after training (P

The main purpose of this pilot study was to assess the regional diagnostic reference level (RDRL) of computed tomography (CT) examinations to optimise medical exposure in five pediatric medical imaging centers in Tehran, Iran where the most frequent CT examinations were investigated. For each patient, CT volume dose indexes (CTDIvol) and dose length product (DLP) in each group were recorded and their third quartile was calculated and set as RDRL. Pediatrics were divided into four age groups (

Iodine-131 (I-131) therapy is one of the conventional approaches in the treatment of patients with differentiated thyroid carcinoma (DTC). The radioiodine agents also accumulate in the other organs that cause pain and damage to the patients. Radioiodine therapy is associated with various gastrointestinal (GI) toxicities. In this study, GI side effects of the radioiodine therapy were investigated. GI toxicities of the radioiodine therapy were studied in 137 patients with histologically proven DTC in Jun-Nov 2014. All the patients were treated by radioiodine agents in the research institute of Shariati Hospital, Tehran, Iran. The patients were examined 48 h after prescription (before discharge) and their GI side effects were registered. Correlation of the age, gender, administered dose, administered dose per body weight as the independent factors, and GI side effects were analyzed using the Pearson correlation test with Statistical Package for the Social Sciences (SPSS) version 20. Regression coefficients and linearity of the variable were investigated by MATLAB software. Line fitting was performed using MATLAB curve-fitting toolbox. From the subjects, 38 patients had GI complaints (30.4%). Significant factors influencing GI side effects were dose per body weight and administered doses. There was no significant correlation between age and gender as the independent parameters and GI complaints. The most prevalent GI side effect was nausea that occurs in 26.4% of the patients. From the results, it could be concluded that the GI side effects could be prevented by administering a safe radioiodine dose value less than 5,550 MBq.

The purpose of this study was to evaluate the effects of the gantry angulation on dose profiles along the z-axis, the CTDIW value and the CTDIW efficiency in the head examinations. A Monte Carlo simulation model of a GE LightSpeed 16-slice CT scanner was developed by a GATE toolkit. The CTDI100 in air at the isocenter and in a head dosimetry phantom were measured using a pencil ion chamber. Dose profiles were studied in the central and peripheral holes of the head phantom using thermoluminescence LiF disc dosemeters for gantry angulations of 0°, 10° and 20°. Results show a small shift for only the peripheral dose profiles with increasing the gantry angulation (maximum shift of 24 mm at 20°). The peak amplitude of the dose profiles was reduced for both of the central and peripheral holes by ~5%, while the CTDIW values and the CTDIW efficiencies did not change significantly.

Cone beam computed tomography, CBCT, is a kind of CT scanner producing conical diverging X-rays, in which a large area of a two-dimensional detector is irradiated in each rotation. Different investigations have been performed on dosimetry of dental CBCT. As there is no special protocol for dental CBCT, CT scan protocols are used for dosimetry. The purpose of this study is measurement of dose to head and neck organs in two CBCT systems, i.e. Planmeca 3D Mid (PM) and NewTom VGi (NT), using thermoluminescence dosimetry and Rando phantom. The thermoluminescent dosimetry (TLD)-100 chips were put at the position of different organs of the head and neck. Two TLD-100 chips were inserted at each position, the dose values were measured for several different field sizes, i.e. 8 × 8, 12 × 8 and 15 × 15 cm2 for NewTom, and 10 × 10 and 20 × 17 cm2 for Planmeca systems. According to the results, the average effective dose in PM is much more than the NT system in the same field size, because of the greater mAs values. For routine imaging protocols used for NT, the effective dose values are 70, 73 and 121 µSv for 8 × 8, 12 × 8 and 15 × 15 cm2 field sizes, respectively. In PM, the effective dose in 10 × 10 cm2 and 17 × 20 cm2 is 259 and 341 µSv, respectively.

Purpose A new quality-control-based (QC-based) method is introduced to obtain correction factors to be applied to displayed patient dose indices (CTDI Vol and DLP) on CT scanner consoles to verify improvement of dose surveys for diagnostic reference levels (DRLs) determination. Method An available data-base of QC documents and reports of 57 CT scanners in Tehran, Iran was used to estimate CTDI Vol , DLP and relevant correction factors for three CT examination types including head, chest and abdomen/pelvis. The correction factor is the ratio of QC-based estimated dose to displayed dose. A dose survey was performed by applying on-site “data collection method” and correction factors obtained in order to select CT scanners in three modes for determination of CT DRLs by inclusion of: (a) all CT scanners before displayed dose indices were corrected (57), (b) only CT scanners calibrated by QC experts (41) and (c) all CT scanners after displayed dose indices were corrected (57). Results For the 41 CT scanners, correction factors of three examination types obtained in this study are within the acceptance tolerance of IAEA HHS-19. The correction factors range from 0.45 to 1.7 (average of 3 examinations) which is due to the change in the calibrated value of CTDI Vol over extended time. The DRL differences in three modes are within ±1.0% for CTDI Vol and ±12.4% for DLP. Conclusions The “QC-based correction method” applied to mode (c) has improved the DRLs obtained by other two modes. This method is a strong alternative to “direct dose measurement” with simplicity and cost effectiveness.

In recent years, with the introduction of 64-slice CT and dual-source CT technology, coronary CT angiography (CCTA) has emerged as a useful diagnostic imaging modality as a non-invasive assessment of coronary heart disease. CT produces a larger radiation dose than other imaging tests and cardiac CT involves higher radiation dose with the advances in the spatial and temporal resolution. The aims of this study are patient dose assessment and establishment of national diagnostic reference level for CCTA in Iran. A questionnaire was sent to CCTA centers. Data for patient and CT protocols were obtained. The volumetric CT dose index (CTDIvol), dose length product (DLP) and total DLP were considered in the 32 cm standard body phantom. Calculation of estimated effective dose (ED) was obtained by multiplying the DLP by a conversion factor [k = 0.014 mSv (mGy·cm)-1]. Mean value of CTDIvol and DLP for CCTA was 50 mGy and 825 mGy·cm. The third quartile (75th) of the distribution of mean CTDIvol (66.54 mGy) and DLP (1073 mGy·cm) values was expressed as the diagnostic reference level (DRL) for CCTA in Iran. The median of ED was 10.26 mSv and interquartile range of ED was 7.08-15.03 mSv. A large variety in CTDIvol and DLP among CT scanner and different sites due to variability in CT parameter is noted. It seems that training could help to reduce patient's dose.

High diagnostic sensitivity and specificity while maintaining the least dose to the patient is the ideal mammography. The objective of this work was to evaluate patient dose and image quality of mammograms to propose corrective actions. The image quality for 1242 patient in 7 mammography facilities in Tehran city was evaluated based on selected image quality criteria using a three-point scale. Clinical image quality, the entrance surface air kerma, the average glandular dose and optical density of films for standard PMMA phantom of 4.5 cm thickness were evaluated. The results showed that up to 72 % of mammograms were in good condition to be diagnosed, and only about 3.4 % of the images were unacceptable or with suboptimal quality. The entrance surface air kerma values were in the range of 3.8-10.5 mGy, average glandular dose 0.5-1.8 mGy and optical density of films 0.74-2.03. The image quality evaluation after correction actions, periodic image quality evaluation and using the correct equipment certainly will improve patient dose.