Background There is lack of guidance on specific CT protocols for imaging patients with coronavirus disease 2019 (COVID-19) pneumonia. Purpose To assess international variations in CT utilization, protocols, and radiation doses in patients with COVID-19 pneumonia. Materials and Methods In this retrospective data collection study, the International Atomic Energy Agency (IAEA) coordinated a survey between May and July 2020 regarding CT utilization, protocols, and radiation doses from 62 healthcare sites in 34 countries across five continents for CT exams performed in COVID-19 pneumonia. The questionnaire obtained information on local prevalence, method of diagnosis, most frequent imaging, indications for CT, and specific policies on use of CT in COVID-19 pneumonia. Collected data included general information (patient age, weight, clinical indication), CT equipment (CT make and model, year of installation, number of detector rows), scan protocols (body region, scan phases, tube current and potential), and radiation dose descriptors (CT dose index (CTDI vol ) and dose length product (DLP)). Descriptive statistics and generalized estimating equations were performed. Results Data from 782 patients (median age (interquartile range) of 59(15) years) from 54 healthcare sites in 28 countries were evaluated. Less than one-half of the healthcare sites used CT for initial diagnosis of COVID-19 pneumonia and three-fourth used CT for assessing disease severity. CTDI vol varied based on CT vendors (7-11mGy, p<0.001), number of detector-rows (8-9mGy, p<0.001), year of CT installation (7-10mGy, p=0.006), and reconstruction techniques (7-10mGy, p=0.03). Multiphase chest CT exams performed in 20% of sites (11 of 54) were associated with higher DLP compared with single-phase chest CT exams performed in 80% (43 of 54 sites) (p=0.008). Conclusion CT use, scan protocols, and radiation doses in patients with COVID-19 pneumonia showed wide variation across healthcare sites within the same and different countries. Many patients were scanned multiple times and/or with multiphase CT scan protocols. See also the editorial by Lee .

The study was done to establish the relationship between measured renal volume and body parameters to estimate standard reference value of renal volume related body parameters (RV-BMI, RV-BSI and RV-BSA) in Ghana for clinical application. The estimates were done based on age and gender variation and compare the established standard reference renal volume with its related body parameters. The weight and BMI measuring machine together with tape measure and glass beaker were the measuring tools used. The procedure involve measurement of body height and weight and using the estimated values to calculate BMI with the BMI calculator. It also involve using DuBois formula to estimate local standard reference values of BSI and BSA in Ghana. The reference standard renal volume was determined using water displacement with the Archimedes' principle to confirm the established values in Ghana. These value were compare with established standard reference renal volume model in Ghana which were estimated using abdominal images on MeVisLab application software platform and determined the relationship between these parameters. The determined Ghanaian standard reference renal volume were: 146.74cm3, 151.76cm3, 142.04cm3 and 148.29cm3 for male and female, with its corresponding right and left kidneys respectively. The estimated mean BMI, BSI and BSA were; 25.19kg/m2 39.81 kg/m2 and 2.02m2 for male and 21.91kg/m2 36.58kg/m2 and 1.69m2 for female respectively. Hence from these set of values, the relationship between renal volume and its related BMI was determined to be 6.04cm3-kg/m2 for male and 6.47cm3-kg/m2 for female. While the male RV related-BSA was also determine to be 74.05cm3-m2 and 84.09cm3-m2 for female. Finally, the renal volume related-BSI was also estimated to be 3.81cm3-kg/m2 for male and 3.88cm3-kg/m2 for female. The standard reference renal volume related BMI, BSI and BSA are recommended to be used for renal assessment for clinical application in Ghana.

The heart is a muscular organ about the size of a closed fist that function by pumping blood throughout the body making the body size extremely important in its performance. Hence, the work done by the heart depend largely on the total body size of the individual, measurements of which depends on the weight and height to estimate BMI, BSA and BSI. The aim of the study was to establish Ghanaian based standard reference values of cardiothoracic ratio and determine the relationship with body parameters for clinical application. The maximum transverse diameter of the heart was obtained by adding the widest distance of the right heart border from the midline and the left heart border to the midline (cardiac diameter). This value was then divided by the maximum transverse diameter of the thorax (the thoracic diameter) to give the cardiothoracic ratio (CTR). Which is described as a ratio of the cardiac width as against thoracic width. The measured CTR was approximately 15: 33 (cm) and is therefore within the normal limit of 50%. This is because a CTR of greater than fifty percent is abnormal, in terms of Posterior - Anterior (PA) or an Anterior - Posterior (AP) view. In addition, the height and weight were measured to estimate the BMI, BSA and BSI and the relationship of these parameters with the measured cardiothoracic ratio. The result shows that BSI better correlate with the cardiothoracic ratio than any other body parameter with 92.53% accuracy rate. The determination of the CTR which represent the size of the normal heart is of the greatest importance to cardiologists. This is because the heart size enlargement is better assess by determining the ratio of size of the heart (cardiac diameter) as against the size of the chest wall (the thoracic diameter). This is use for initial assessment of heart condition by cardiologist, with a standard adult heart having a CTR value of 0.5. The study shows that a normal size is so variable and depends so greatly on the sex, age and body parameters of the study population. In conclusion, the study will serve as basis of the relationship between body parameter and the CTR. It also established that a deviation of heart size with BSI may reveal an underlying pathologic condition, and called for further studies to be conducted for clinical decision.

The aim of this study is to estimate the effective dose and assess the lifetime attributable risk of cancer incidence of patients undergoing computed tomography scan at the Korle-Bu Teaching Hospital in the Greater Accra Region of Ghana. Data on Volume CT Dose Index ( ) and Dose Length Product ( ) displayed on the scanner control console was recorded after confirmation of the results by performing independent checks on a phantom. The effective doses were estimated using the  displayed and the anatomic region specific conversion factors ( ). The average effective dose for the head, abdomen, chest, neck, and pelvis were 3.63± 2.39mSv, 15.37±8.49 mSv, 12.72 ± 13.97 mSv, 4.04 ± 1.47 mSv and 15.8 ± 3.59 mSv respectively. Effective doses for the head and neck were within the typical range of (1-10mSv) for CT examinations whilst abdomen, chest and pelvis were above 10mSv. The average life attributable risk of cancer incidence for each region of examination were determined from the effective dose, sex and age using  the model proposed in BEIR VII Report . The average cancer risk incidence for head, neck, chest, abdomen and pelvis examinations were low in the range 1 in 10,000 to 1 in 1,000. There were wide variations in the effective dose values obtained for the same region under examination. This trend calls for the optimization of CT examination protocols to be established to ensure that patient doses are as low as reasonably achievable, economic and social factors being taken into account especially for chest examinations.

The quantities that determine the relative image noise level by either increasing or reducing its value are photon quality (kVp) and photon quantity (mAs). This study is to determine the effect of LET, energy and particle fluence on the renal surface area during abdominal CT scan. The method involve extracting three exposure parameters from image data using MVL DICOM application software including: kVp, mA and scan time. The kVp or the photon peak energy which is applied in the A-P direction during abdominal CT scan was used to estimate linear energy transfer. While the particle fluence and the energy fluence were estimated from the effective mAs and the kVp on the total renal surface respectively. The effective mAs were estimated by dividing the mAs by the average pitch factor of approximately 0.813. In all the examinations, the average protocol setting in terms of exposure time and kilovolts peak were 500s and 120keV respectively. While the average protocol in all the centers recorded a mean effective milliamp second (mAs) of 59.27 mAs and tube current of 94.22A. The influence of these parameters on abdominal scan depends on the scan time, scan scope, the size of the renal surface area (RSA) which has varied values. The effects of effective mean mAs per unit mean renal surface area, described as mean effective particle fluence were 1.32mAs/cm2 and 1.50 mAs/cm2 for male and female respectively. The energy fluence, which is the photon energy per unit renal surface area estimated to have a mean value of 4.02 keVcm-2 and 4.51 keVcm-2 for male and female respectively. In addition, the maximum and minimum variations of all the measured parameters. The LET, which described the lost in photon energy as it traverses across the renal tissues in the A-P direction was estimated, with a mean value of 2.60 keV/µm and 2.67 keV/µm for male and female respectively. The maximum and minimum LET values were 4.49 keV/µm and 1.90 keV/µm for male and 5.26 keV/µm and 1.98 keV/µm for female respectively. The maximum measured values were below the critical LET values estimated to be between 15 to 20 keV/µm. These estimated risk parameters were used to predict the effect on abdominal and kidney tissues using the various modeled equations.