Search

Computerised tomography (CT) continues to be a corner stone medical and radiologic imaging modalities in radiology and radiotherapy departments. Its importance lies in its efficiency in low contrast detectability (LCD). The assessment of such capabilities requires rigorous image quality analysis using special designed phantoms with different densities as well as variation in atomic mass numbers (A) of the material. Absence of such ranges of densities and atomic mass numbers, limits the dynamic range of assessment. An example is Catphan phantom which represents only three subject contrast levels 0.3, 0.5 and 1 per cent. This project aims to present a phantom with extended range of available subject contrast to include very low-level values and to increase its dynamic scale. With this design, a relatively large number of different contrast objects (holes) can be presented for imaging by a CT scanner to assess its LCD ability. We shall thus introduce another LCD phantom to complement the existing ones, such as Catphan. The cylindrical phantom is constructed using Poly (methyl methacrylate) (PMMA), with craters (holes) having dimensions that gradually increase from 1.0 to 12.5 mm penetrated in configuration that extend from the centre to the corner. Each line of the drilled holes in the phantom is filled with contrast material of specific concentrations. As opposed to the phantom of low detail contrast used in planar imaging, the iodine (contrast material) in this phantom replaces the depth of the phantom holes. The iodine could be reduced to 0.2 l milli-Molar (mM) and can be varied for the next line of holes by a small increment depending on the required level of contrast detectability assessment required. [ABSTRACT FROM AUTHOR]

Breast cancer is a common malignancy for females (25% of female cancers) and also has low incidence in males. It was estimated that 1% of all breast malignancies occur in males with mortality rate about 20%, with annual increase in incidence. Risk factors include age, family history, exposure to ionizing radiation and high estrogen and low of androgens hormones level. Diagnosis and screening are challenging due to limiting effectiveness of breast cancer screening. Therefore, patients may expose to ionizing radiation that may contribute in breast cancer incidence in males. In literature, limited studies were published regarding radiation exposure for males during mammography. The objective of this research is to quantify patient doses during male mammogram and to estimate the projected radiogenic risk during the procedure. In total, 42 male patients were undergone mammogram for breast cancer diagnosis during two consecutive years. The mean and range of patient age (years) is 45 (23–80). The mean and standard deviation (SD) of the peak tube potential and tube current time product are 28.64 ± 2. and 149 ± 35.1, respectively. The mean, and range of patients' entrance surface air kerma (ESAK, mGy) per single breast procedure was 5.3 (0.47–27.5). Male patient's received comparable radiation dose per mammogram compared to female procedures. With increasing incidence of male breast cancer, proper guidelines are necessary for the mammographic procedure are necessary to reduce unnecessary radiation doses and radiogenic risk. • Average glandular doses were quantified for 42 male patients' mammograms. • The radiogenic risk for male procedure is low compared to other procedures. • Elimination of the radiation exposure for young male and girls is recommended. • Males received comparable dose to females mammography procedure. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) procedures are the largest source of medical radiation exposure in children and adults. Numerous children undergo high-radiation-dose examinations due to the increasing utilization of CT in children and the wide range of radiation doses. It is therefore necessary to protect pediatric patients, because of their higher sensitivity to ionizing radiation. This study aimed to establish a multicenter cohort of pediatric patients who received CT scans and predict the radiation-related cancer risk. Ninety-five patients who underwent various CT scans [brain 64 (67.4%), chest 14 (14.7%), abdomen 17 (17.9%)] were referred to one of three hospitals. All patients were examined using one of three identical multi-detector CT machines (Toshiba Aquilion 64) according to standard departmental imaging protocols. The average effective doses per scan for brain, chest, and abdominal procedures were 49.7, 34, and 40 mSv, respectively. Dose-reduction measures might significantly decrease the number of radiation-induced malignancies in children. • Radiation dose was quantified for CT brain, chest, and abdomen procedures. • Three 64 multi-detector CT machines from a single vendor were used. • The radiogenic risks per procedure are 6.5, 4.4, and 5.2 per 10-3 CT brain, chest, and abdomen, respectively. • Children received high-dose per exam and higher than previously reported. [ABSTRACT FROM AUTHOR]

Radiation exposures for medical purposes is remained the main sources to public from manmade radiation. The aims of the study are to patients' radiation doses during specific planar radiography procedures. A total of 247 patients were examined at four radiology department in Khartoum state, Sudan. The absorbed dose to air at the center of the beam, including backscattered radiation, is known as the entrance surface air kerma (ESAK, mGy). ESAK (K e) can be computed using the product backscatter factor (B) and incident air kerma Ki. The mean ESAK (mGy) for the chest, skull, abdomen, hip, lumbar spine and limbs procedures were 0.2, 0.76, 97, 1.88, 1.25, 2.25 and 0.30 mGy, respectively. The average ESAK (mGy) values attained for eight planar radiography procedures are comparable or slightly lesser than the previously published studies for the chest, pelvis, and limbs. The patient doses during the skull, abdomen, hip, and spinal cord (lumbar spine) are lower than the previously published values. • ESAK during eight planar imaging procedures were evaluated. • The radiographic equipment performance in all hospitals was acceptable. • Wide variability in the patients' doses per radiographic was noticed. • Standardized imaging protocols are recommended. [ABSTRACT FROM AUTHOR]

Computed tomography perfusion (CTP) is contrast-enhanced dynamic imaging of the brain utilized to assess the blood flow volume and transmit time to the brain's parenchyma. Stroke is the world's second greatest cause of mortality, accounting for 11% of all deaths, and a major cause of disability. Previous studies reported a high radiation dose per procedure with an eye lens equivalent dose (mGy) ranging from 81.0 mGy to 348.0 mGy. This study's objective is to evaluate patients exposure during CTP procedures. Materials and methods. Three hundred twenty patients with ischemic stroke underwent CTP were examined at King Fahad Medical City (KFMC). The imaging protocol consists of plain CT, CT angiography (CTA), CTP, Angiography. The volume CT Dose Index (CTDIvol, mGy) and dose length product (DLP, mGy.cm) were registered from the PACS system. The effective dose calculation (E, mSv) was extrapolated using computer software. For the CTP procedure, the mean and range of DLP (mGy.cm) for the complete procedure, CT brain, CTA, CTA digital subtraction angiography (DSA), and CTP were 1045 (105–3072), 843 (277–1530), 470.5 (210–1356), 238.8 (105–439), 2712(2012–3072) examinations, respectively. The mean and range of the effective dose (mSv) and CTDIvol (mGy) were 13.2 (10.6–17.1), 80.5 (6.11–256), in that order. The patients' doses showed wide variation due to the selection of multiple phases of acquisition and exposure factors. The dose is higher than most previous studies. Radiation dose optimization is recommended by establishing diagnostic reference level (DRL), proper CT machine setting, and increasing operators' awareness regarding radiation risks. • Multimodal computed tomography (CT) radiation doses were quantified for 72 patients. • Multimodal consists of noncontrast, angiography, digital subtraction angiography, and Perfusion CT procedure. • Multimodal CT brain procedure resulted in an effective dose of 6–15 mSv. • The use of the CTP- DSA procedure exposes the patients to unnecessary radiation. [ABSTRACT FROM AUTHOR]

The positron emitters (18F-Sodium Fluoride (NaF)) and X-rays used in Positron emission tomography (PET) combined with computed tomography (PET/CT) imaging have a high radiation dose, which results in a high patient dose. The present research intends to determine the radiation dose and risks associated with PET/CT- 18F-Sodium fluoride examinations in patients. The 18F–NaF PET/CT was used to investigate the doses of 86 patients. Patient exposure parameters and ImPACT software were used to calculate mean effective doses. The administered activity of 185 MBq (5.0 mCi) per procedure has a mean and range based on the patient's BMI (BMI). The range of patient effective doses per procedure was found to be 4–10 mSv, with a radiation risk of 1 × 10−5 per procedure. Patient doses are determined by the patient's size, scanner type, imaging protocol, and reconstruction method. For further dose reduction, proper justification and radiation dose optimization is required. • Effective doses were estimated for patients undergoing PET/CT procedures. • CT contributed 66.7% to patient cumulative effective doses (mSv) while (18F–NaF, PET) contributed 33.3%. • Patients dose optimization is recommended during PET/CT examinations. [ABSTRACT FROM AUTHOR]

The objective of this study is to assess the patients' effective and organ dose during theranostic applications in Kuwait. In total, eighteen adults' patients were conducted nuclear medicine procedures with 177Lu Dotatate for theranostic purpose in Kuwait Cancer control center (KCCC), Kuwait. Medium energy collimator (MEC) (208 keV Scatter 26% better than 113 keV Scatter 60%) was utilized to obtain scans in definite time intervals ranged from one to 2 h (before voiding), 6:00, 24:00, 48:00, 72:00 h. Patients, tissue and organ radiation doses were computed utilizing OLINDA/EXM Software. The average radiation effective dose (in mSv/MBq) for bladder, liver, and both kidneys (left & right), were 0.36, 0.08, 0.61 & 0.60. The range of the effective dose was from 0.55 mSv to 7.7 mSv. The acquired scans using 177Lu were delivered diagnostic findings. The patients' effective dose is lower compared to the previous studies. Variation is attributed to the departmental protocol and administered activity. The values of the mean organ dose were comparable and lower than previously published studies. Different organs have different level of doses, which may affected by the presence of the metastatic tumors in the entire organ. • Patients' organs dosimetry in targeted radionuclide therapy were carried out in Kuwait Cancer Control Centre. • A total of 18 patients were undergone theranostic procedures with 177Lu Dotatate. • Organ and total patients doses were calculated using Organ Level INternal Dose Assessment (OLINDA) Software. • Optimization of the PET/CT imaging protocol is recommended to assure that patients received a minimal effective dose. [ABSTRACT FROM AUTHOR]

The purposes of this study are to estimate patient's radiation doses and radiogenic risk in vascular lower limb computed tomography (CT). In total, 188 (109 (68%) males and 79 (42%) females) patients undergone vascular CT for the lower limbs at three radiology departments. Three CT scanners, 160, 128, and 64 slices CT, were used in this study. CT-Expo and ImPACT CT dose estimation software were used to extrapolate the effective dose. The overall average and range of volume CT dose index (CTDIvol (mGy) and dose length product (DLP) (mGy.cm) 7.3 (2.3–22.9), and 3000 (279.1–8374.4) the same order. The overall effective dose average value was 18 mSv per procedure. The proposed diagnostic reference level (DRL) values are 9 mGy (CTDIvol) and 2500 mGy cm (DLP) per vascular lower limb CT procedure. The risk of cancer from the peripheral CT angiography procedures ranges from 1 in 1000 to 1 in 3000 procedures. The cancer risk per procedure should be considered during the justification and image acquisition stages. • Peripheral CT angiography for lower extremities were performed using three CT machines. • CT dose per procedure (DLP (mGy.cm) is higher up to 10 times compared to previous. • Patients are being seen to be receiving unnecessary radiation doses during triphasic CT abdomen procedure. • A local diagnostic reference level was proposed was established for further dose reduction. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) are often used for adult and pediatric patients. This is basically due to its powerful diagnostic capabilities in providing the tiniest details of pathologies in the body. Nevertheless, this detailed and accurate imaging occurs at the expense of the high doses received by the patients, although in general, the benefits outweighs the risks precisely of malignancy. Pediatrics are radiosensitive more than adults due to their longer life expectancy and their rapidly dividing cells. This study aims at measuring and evaluating pediatric patient doses in four hospitals equipped with 16, 20 and 128 CT detectors. Forty-eight pediatric patients who underwent brain (72.7%) and abdomen (36.3%) Computed Tomography are included in this study. Data includes CTDI vol (mGy) and DLP (mGy.cm). CTDOSE computer software which is based on Monte Carlo simulations was used to calculate the effective and organ equivalent doses (mSv). The CTDIvol (mGy) per procedure range was 11.0–95.0 mGy for brain CT and 3.0–30.0 mGy for abdomen CT. DLP on the other hand ranged between 129.0 and 2510.0 mGy cm for brain CT and 84.0–1604.0 for abdomen CT. The high doses were attributed to the fact that the protocols used for pediatric patients were the adult protocols, not bearing in mind the high radio-sensitivity of the pediatrics. Establishing a protocol for pediatric CT is hence of great importance to prevent them from receiving unnecessary high doses which may eventually cause cancer. • The radiation doses during specific pediatric CT examinations in four hospitals were evaluated. • Patient dose per CT procedure ranged from 84.0 to 2510.0 mGy cm. • Adults protocols used for pediatric patients resulted in unnecessary exposure. • Standardizing imaging protocols during pediatric CT imaging is recommended. [ABSTRACT FROM AUTHOR]

Occupational radiation exposure can occur due to various human activities, including the use of radiation in medicine. Occupationally exposed personnel surpassing 7.4 millions, and respresent the biggest single group of employees who are exposed to artificial radiation sources at work. This study compares the occupational radiation dose levels for 145 workers in four different hospitals located in the Aseer region in Saudi Arabia. The occupational exposure was quantified using thermoluminescence dosimeters (TLD-100). The levels of annual occupational exposures in targeted hospitals were calculated and compared with the levels of the international atomic energy agency (IAEA) Safety Standards. An average yearly cumulative dose for the two consecutive years. The average, highest and lowest resulted occupational doses under examination in this work is 1.42, 3.9 mSv and 0.72 for workers in various diagnostic radiology procedures. The resulted annual effective dose were within the IAEA approved yearly dose limit for occupational exposure of workers over 18, which is 20 mSv. Staff should be monitored on a regular basis, according to current practice, because their annual exposure may surpass 15% of the annual effective doses. • Annual occupational dose (Hp(10) were evaluated at four diagnostic radiology department. • Staff doses represent approximately 15% of the annual effective dose. • Students and trainees should be monitored on a regular basis, according to current practice. • Occupational exposure is comparable with the most previously published studies. [ABSTRACT FROM AUTHOR]

Exposure to ionizing radiation may induce cancer risk to the patients proportional to the radiation absorbed dose and the organ sensitivity. Therefore protection of radiation exposure is essential to minimize the radiation cancer risk and prevent the deterministic effects. The International Atomic Energy Agency (IAEA) encourages member countries to establish national diagnostic reference levels (DRLs) to reduce unjustified radiation exposure. This study establishes a local DRL for computed tomography (CT) abdomen and pelvis procedures. In total, 1444 CT abdomen procedures were carried out during nine months. CT abdomen procedures were carried out at King Faisal Specialist Hospital and research center using six CT machines from different vendors. The mean and range of patients' weight (kg) are 50 (42–120). The recommended DRLs values in DLP (mGy.cm) and CTDIvol (mGy) were 900 and 15 per CT abdomen and pelvis procedure, respectively. 3% (41 cases) were higher than the national DRL for CT abdomen and pelvis. The proposed DRL values are slightly higher than the European and the American College of Radiologists (ACR) DRL values in DLP. The purpose of DRL in terms of CTDIvol (mGy) is comparable with the international guidelines. Thus reducing the scan length, is recommended ensuring that patients receive a minimal possible radiation dose while maintaining the image quality. • Patient radiation was calculated for CT abdomen examinations. • Six multi-detector CT machines 64, 128, 384 and 256 (three machines) were used. • 3% (41 cases) were higher than the national DRL for CT abdomen and pelvis. • The proposed DRL is higher than previously reported values in Europe. [ABSTRACT FROM AUTHOR]

Computed tomography (CT) is the leading source of the cumulative effective doses to the general populace from medicinal and artificial sources. With the increased use of CT examinations comes the concern regarding the health effects of unnecessary radiation exposure and the need to optimize the doses that patients receive. The current study evaluates the patients' doses during specific CT procedures and establishes institutional diagnostic reference levels (DRLs) for the frequent CT scans performed. 8156 CT scan examinations were performed during three years from 2015 to 2018 using a single CT scan machine at our institution. Data from the six most common examinations were analyzed. The volume CT dose index (CTDIvol (mGy)) and dose length product (DLP) distribution's median and 75th percentile values were computed. The results were descriptively compared with DRLs from different countries and regions. The six most common examinations constituted 5815 studies. We established our DRLs as the median value of CTDIvol (mGy)| and DLP (mGy × cm) as follows: CT of the brain: 35.0 mGy and 839 mGy × cm, respectively; chest with contrast: 4 mGy and 148 mGy-cm, respectively; chest without contrast: 5 mGy and 190 mGy-cm, respectively; abdomen and pelvis with contrast: 8 mGy and 636 mGy-cm, respectively; abdomen and pelvis without contrast 8 mGy and 568 mGy-cm, in that order; abdomen, pelvis, and kidneys: 11 mGy and 458 mGy × cm, respectively. Our values for brain and chest CTs were lower than the international DRLs, while those for abdominal imaging were higher. The established DRLs offer an opportunity for us to optimize the dose delivered to patients and compare them to the national benchmarks when they are issued. The study revealed that CT dose showed wide discrepancies for the same procedures at the department levels suggesting that the practice was neither optimized nor harmonized. Therefore, DRL should be reassessed after the operators' training and awareness to reduce the patients' dose and related radiogenic risk to its minimal value. • DRL was quantified for six standard CT examinations. • The study revealed that CT dose showed wide discrepancies for the same procedures. • The proposed DRLs are within the international values. • DRL should be reassessed after the technologists' training on imaging protocol optimization. [ABSTRACT FROM AUTHOR]

Occupational exposure to ionizing radiation of medical personnel is very common at radiology and nuclear medicine departments. Strict regulations and guidelines for the exposure of staff working in such departments were regulated by international authorities such as the International Atomic Energy Agency (IAEA), and the International Commission on Radiological Protection (ICRP) as well as national protocols. In order to reduce stochastic effects, for example, radiation induced carcinogenesis, the exposure of staff working at nuclear medicine department should be maintained at levels lower than 20 mSv per year or 100 mSv in five years. The objective of this study is to measure staff radiation dose at four radiology departments in the south region of the Kingdom of Saudi Arabia. Exposures received by a total of 106 staff working at the radiology department were monitored for two consecutive years using calibrated Thermoluminecnt dosimeters (LiF:Mg:Ti (TLD-100). Exposure was then quantified in terms of deep dose: Hp (10). The TLD signal was obtained using an automatic TLD reader (Harshaw 6600). The overall annual dose for staff was 1.4 ± 0.37 (0.67–8.74). The study revealed that the annual radiation exposure in the four-radiology department is below the annual dose limits. However, staff doses could be reduced if proper radiation protection are followed. • Staff annual radiation dose were assessed for radiology technologists for two consecutive years. • Occupational doses were quantified with LiF: Mg, Ti (TLD-100). • 90% of monitored staff received an annual occupational dose below 2.0 mSv. • Radiology technologists are well protected against occupational exposure. [ABSTRACT FROM AUTHOR]

Ionizing radiation exposure from medical applications is increasing annually worldwide. It was estimated that 325 million dental procedures were performed in the United States. Radiation exposure from dental radiography consists of intraoral, panoramic, and 3D imaging cone-beam computed tomography (CBCT) imaging. Recent studies reported an association between dental imaging procedures and increased cancer probability of brain and thyroid. Previous studies showed that some dental imaging practices exposed patients and staff to unnecessary radiation doses due to incorrect image acquisition and insufficient radiation protection measures. This study aims to (i) measure the occupational and patients doses during dental procedures and (ii) assess the current imaging techniques and radiation protection practices. Two hundred fourteen patients were evaluated for periapical, bitewing, cephalometric, occlusal, and panoramic procedures. Organ equivalent doses were quantified for the breast, eye lens, and thyroid gland during CBCT procedure. Occupational and ambient dose assessment were assessed using calibrated thermoluminescent dosimeters (TLD-100(LiF: Mg. Ti). Ambient doses were measure at different locations at the department using TLDs. Patients' radiation doses were quantified using kerma area product (PKA (mGy.cm) and the entrance surface air kerma (ESAK (mGy). Fixed tube voltage (65 kVp) and tube current-time product (7 mAs) were used. The overall mean, sd, and range of patients dose values during intraoral (mGy), panoramic and CBCT examinations were 4.6 ± 0.7 (1.4–7.1), 135 ± 45 (75.2–168.5), and 215 ± 165 (186–2115), respectively. The mean and range of the annual occupational doses (mSv) were 1.4 (0.6–3.7), which below the annual dose limits for radiation workers (20 mSv/y). The study showed that inadequate radiation protection for patients existed in terms of the use of the thyroid shield, the technologist's presence inside the room during radiation exposure. Patients' radiation doses were comparable with the international diagnostic reference level (DRL). Staff education and training in radiation protection aspects are highly recommended. • Radiation doses from intraoral, panoramic, and 3D imaging cone-beam computed tomography imaging were quantified. • Ambient and occupational doses were measure at different locations at the department using TLD. • The study showed that inadequate radiation protection for patients existed in terms of the use of the thyroid shield. • CBCT dose values, the patient radiation dose is around two times higher than for a panoramic imaging procedure. • The mean and range of the annual occupational doses (mSv) were below the annual dose limits for radiation workers. [ABSTRACT FROM AUTHOR]