No abstract

No abstract

Introduction:As of early December 2019, COVID-19, a disease induced by SARS-COV-2, has started spreading, originated in Wuhan, China, and now on, have infected more than 2 million individuals throughout the world.Purpose: This study aimed to nowcast the COVID-19 outbreak throughout Iran and to forecast the trends of the disease spreading in the upcoming month. Methods:The cumulative incidence and fatality data were extracted from official reports of the National Ministry of Health and Medical Educations of Iran. To formulate the outbreak dynamics, six phenomenological models, as well as a modified mechanistic Susciptible-Exposed-Infectious-Recovered (SEIR) model, were implemented. The models were calibrated with the integrated data, and trends of the epidemic in Iran was then forecasted for the next month. Results:The final outbreak size calculated by the best fitted phenomenological models was estimated to be in the range of 68,486 to 118,923 cases; however, the calibrated SEIR model estimated that the outbreak would rage again, starting from April 26. Moreover, projected by the mechanistic model, approximately half of the infections have undergone undetected. Conclusion:Although the advanced phenomenological models perfectly fitted the data, they are incapable of applying behavioral aspects of the outbreak and hence, are not reliable enough for authorities' decision adoptions. In contrast, the mechanistic SEIR model alarms that the COVID-19 outbreak in Iran may peak for the second time, consequent to lifting the control measures. This implies that the government may implement a more granular decision making to control the outbreak. *

This study was conducted to determine first local diagnostic reference levels (DRLs) and achievable doses (ADs) for pediatric patients during the most common computed tomography (CT) procedures in Yazd province. The DRL was obtained based on volume CT dose index (CTDIvol) and dose length product (DLP) for four various age groups of children. Data were collected from the most commonly performed pediatric CT scans, including abdomen–pelvis, chest, brain and sinus examinations, at six high-loaded institutes. The patients’ data (766 no.) in terms of CTDIvol and DLP were obtained from four age groups: ≤1-, 1–5-, 5–10- and 10–15-y-old. The 75th percentiles of CTDIvol and DLP were considered as DRL values and the 50th percentiles were described as ADs for those parameters. Consequently, the acquired DRLs were compared with other national and international published values. The DRLs in terms of CTDIvol for abdomen–pelvis, chest, brain and sinus examinations were 3, 8, 9 and 10 mGy; 4, 5, 5 and 5 mGy; 25, 28, 29 and 38 mGy; and 23, 24, 26 and 27 mGy for four different age groups of ≤1-, 1–5-, 5–10- and 10–15-y-old, respectively. The DRL values in terms of DLP were 75, 302, 321 and 342 mGy.cm; 109, 112, 135 and 170 mGy.cm, 352, 355, 360 and 481 mGy.cm; and 206, 211, 228 and 245 mGy.cm, respectively, for the mentioned age groups. In this study, the DRL and AD values in the brain examination were greater among the other studied regions. The DRL plays a critical role in the optimization of radiation doses delivered to patients and in improving their protection. This study provides the local DRLs and ADs for the most common pediatric CT scanning in Yazd province to create optimum situation for the clinical practice.

Purpose: Excessive use of Computed Tomography (CT) has become a worrying issue due to the potential risks resulting from radiation exposure. This study was carried out to investigate trends in CT usage in Yazd Province, Iran. Materials and Methods: In the current study, patients were categorized according to their sex and age into two general groups, pediatrics (<18 years old) and adults (≥18 years old), each group falling into multiple subcategories. The performed CT scans were classified into six categories, based on the anatomical area of interest, including head/neck, chest, spine, abdomen-pelvis, extremities, and CT angiography (CTA). The data were collected from 2015 to 2018. Results: The mean number of CT scans increased by the Compound Annual Growth Rate (CAGR) of 11%. Across the procedures, head/neck (with an average contribution of 52% to all CT scans) was the most frequently examined region, whereas CTA had the lowest percentage (2%). More than half of the scans are performed on people over the age of 90, and among those aged<18 years old the most CT scan rates are related to 13-18-year-olds. Conclusion: The number of CT examinations is clearly increasing in Yazd Province. Some of this increase may be warranted because of the improvements in the diagnostic power of CT. The estimated number of pediatric CT scans has risen more than past. Due to the risk of cancer, efforts should be made to reduce unnecessary CT scans.