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Introduction: Computed Tomography (CT) is nowadays used widely to differentiate normal brain cranium sutures from abnormal ones in pediatric patients with the aim of early treatment. This study tried to develop a low-dose CT protocol with the acceptable image quality of skull bone in order to evaluate craniosynostosis. Material and Methods: In this study a cranium bone of human cadaver was scanned with standard and reduced dose protocols. Two radiologists verified the quality of skull bone images acquired from the protocol in which there had been 60% dose reduction to scan pediatric patients. The quality of low dose protocol of three dimensional (3D) CT images of skull bone of 57 pediatric subjects suspected of craniosynostosis were compared with standard-dose skull CT images of 44 patients of the same age range. Volume CT dose index (CTDIvol), dose-length product (DLP), and effective dose (ED) were used to evaluate CT dose protocols. The comparison was made by two sample t-test. Results: Mean and standard deviations of CTDIvol, DLP, and ED of standard and reduced doses were 12.4±2.7 mGy, 191.5±54 mGy.cm, 1.94±0.58 mSv and 5.4±0.2 mGy, 85±9 mGy.cm, 0.77±0.17 mSv, respectively, which had statistically significant difference (a=0.05). The quality of skull bone views obtained from low-dose CT protocol were found to be as good as in standard dose. Conclusion: Standard-dose 3D CT protocol of skull bone can be replaced by a 60%-reduced-dose 3D CT protocol with comparable image quality in pediatric patients suspected of craniosynostosis. [ABSTRACT FROM AUTHOR]

Objectives: The frequency of abdominal computed tomography examinations is increasing, leading to a significant level of patient dose. This study aims to quantify and evaluate the effects of automatic tube current modulation (ATCM) technique on patient dose and image quality in contrast-enhanced biphasic abdominal examinations. Methods: Two different scan protocols, based on constant tube current and ATCM technique, were used on 64 patients who visited our radiology department periodically. For three patient groups with different patient size, results from two protocols were compared with respect to patient dose and image quality. Dosimetric evaluations were based on the Computed Tomography Dose Index, dose length product, and effective dose. For the comparison of image qualities between two protocols, Noise Index (NI) and Contrast to Noise Ratio (CNR) values were determined for each image. Additionally, the quality of each image was evaluated subjectively by an experienced radiologist, and the results were compared between the two protocols. Results: Dose reductions of 31% and 21% were achieved by the ATCM protocol in the arterial and portal phases, respectively. On the other hand, NI exhibited an increase between 9% and 46% for liver, fat and aorta. CNR values were observed to decrease between 5% and 19%. All images were evaluated by a radiologist, and no obstacle limiting a reliable diagnostic evaluation was found in any image obtained by either technique. Conclusion: These results showed that the ATCM technique reduces patient dose significantly while maintaining a certain level of image quality. [ABSTRACT FROM AUTHOR]

Objectives: A nationwide survey was performed assessing current practice of dose data analysis in computed tomography (CT).Material and Methods: All radiological departments in Switzerland were asked to participate in the on-line survey composed of 19 questions (16 multiple choice, 3 free text). It consisted of four sections: (1) general information on the department, (2) dose data analysis, (3) use of a dose management software (DMS) and (4) radiation protection activities.Results: In total, 152 out of 241 Swiss radiological departments filled in the whole questionnaire (return rate, 63%). Seventy-nine per cent of the departments (n = 120/152) analyse dose data on a regular basis with considerable heterogeneity in the frequency (1-2 times per year, 45%, n = 54/120; every month, 35%, n = 42/120) and method of analysis. Manual analysis is carried out by 58% (n = 70/120) compared with 42% (n = 50/120) of departments using a DMS. Purchase of a DMS is planned by 43% (n = 30/70) of the departments with manual analysis. Real-time analysis of dose data is performed by 42% (n = 21/50) of the departments with a DMS; however, residents can access the DMS in clinical routine only in 20% (n = 10/50) of the departments. An interdisciplinary dose team, which among other things communicates dose data internally (63%, n = 76/120) and externally, is already implemented in 57% (n = 68/120) departments.Conclusion: Swiss radiological departments are committed to radiation safety. However, there is high heterogeneity among them regarding the frequency and method of dose data analysis as well as the use of DMS and radiation protection activities.Key Points: • Swiss radiological departments are committed to and interest in radiation safety as proven by a 63% return rate of the survey. • Seventy-nine per cent of departments analyse dose data on a regular basis with differences in the frequency and method of analysis: 42% use a dose management software, while 58% currently perform manual dose data analysis. Of the latter, 43% plan to buy a dose management software. • Currently, only 25% of the departments add radiation exposure data to the final CT report. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to test the hypothesis that unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration in triple-phase abdomen and pelvis computed tomography (CT), and to assess if attenuation value (AV) measurements may be obtained from unenhanced images acquired with three-fold reduced radiation dose. Material and methods: In the standard triple-phase abdomen and pelvis CT protocol (unenhanced, late arterial, and portal venous phase) we decreased the tube current time product only in the unenhanced phase. Arterial and venous phases were performed with the standard scanner settings used in our Institution for routine abdomen and pelvis CT. We compared the AV in manually drawn circular-shaped regions of interest (ROIs) obtained from reduced-dose and standard-dose unenhanced images in 52 patients. All ROIs were set in homogeneous parts of psoas muscle, fat tissue, liver, spleen, aorta, and bladder. Results: There was no statistically significant difference in AV measurements for all considered areas. More noise does not alter the mean AV inside the ROIs. Radiation dose of unenhanced scans was reduced three times and the total dose length product (DLP) in the triple-phase study was decreased by 22%. Conclusions: Unenhanced images performed with three-fold reduced radiation dose allows reliable AV measurements. The unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to test the hypothesis that unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration in triple-phase abdomen and pelvis computed tomography (CT), and to assess if attenuation value (AV) measurements may be obtained from unenhanced images acquired with three-fold reduced radiation dose. Material and methods: In the standard triple-phase abdomen and pelvis CT protocol (unenhanced, late arterial, and portal venous phase) we decreased the tube current time product only in the unenhanced phase. Arterial and venous phases were performed with the standard scanner settings used in our Institution for routine abdomen and pelvis CT. We compared the AV in manually drawn circular-shaped regions of interest (ROIs) obtained from reduced-dose and standard-dose unenhanced images in 52 patients. All ROIs were set in homogeneous parts of psoas muscle, fat tissue, liver, spleen, aorta, and bladder. Results: There was no statistically significant difference in AV measurements for all considered areas. More noise does not alter the mean AV inside the ROIs. Radiation dose of unenhanced scans was reduced three times and the total dose length product (DLP) in the triple-phase study was decreased by 22%. Conclusions: Unenhanced images performed with three-fold reduced radiation dose allows reliable AV measurements. The unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to test the hypothesis that unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration in triple-phase abdomen and pelvis computed tomography (CT), and to assess if attenuation value (AV) measurements may be obtained from unenhanced images acquired with three-fold reduced radiation dose. Material and methods: In the standard triple-phase abdomen and pelvis CT protocol (unenhanced, late arterial, and portal venous phase) we decreased the tube current time product only in the unenhanced phase. Arterial and venous phases were performed with the standard scanner settings used in our Institution for routine abdomen and pelvis CT. We compared the AV in manually drawn circular-shaped regions of interest (ROIs) obtained from reduced-dose and standard-dose unenhanced images in 52 patients. All ROIs were set in homogeneous parts of psoas muscle, fat tissue, liver, spleen, aorta, and bladder. Results: There was no statistically significant difference in AV measurements for all considered areas. More noise does not alter the mean AV inside the ROIs. Radiation dose of unenhanced scans was reduced three times and the total dose length product (DLP) in the triple-phase study was decreased by 22%. Conclusions: Unenhanced images performed with three-fold reduced radiation dose allows reliable AV measurements. The unenhanced phase does not require as high image quality as subsequent phases acquired after contrast administration. [ABSTRACT FROM AUTHOR]

This article reviews issues of radiation protection in children in 52 low-resource countries. Extensive information was obtained through a survey by the International Atomic Energy Agency (IAEA); wide-ranging information was available from 40 countries and data from the other countries pertained to frequency of pediatric CT examinations. Of note is that multi-detector CT (MDCT) was available in 77% of responses to the survey, typically nodal centers in these countries. Nearly 75% of these scanners were reported to have dose displays. The pediatric CT usage was lower in European facilities as compared to Asian and African facilities, where usage was twice as high. The most frequently scanned body part was the head. Frequent use of 120 kVp was reported in children. The ratio of maximum to minimum CT dose index volume (CTDI) values varied between 15 for abdomen CT in the age group 5-10 years and 100 for chest CT in the age group <1 year. In 8% of the CT systems, CTDI values for pediatric patients were higher than those for adults in at least one age group and for one type of examination. Use of adult protocols for children was associated with CTDI or CTDI values in children that were double those of adults for head and chest examination and 50% higher for abdomen examination. Patient dose records were kept in nearly half of the facilities, with the highest frequency in Europe (55% of participating facilities), and in 49% of Asian, 36% of Latin American and 14% of African facilities. The analysis of the first-choice examinations in seven clinical conditions showed that practice was in accordance with guidelines for only three of seven specified clinical conditions. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents results of equivalent dose organ determining to both primary beam and scattered radiation in a computed tomography (CT) procedures. All measurements were carried out to abdomen and critical organ (gonads) area. Selected dosimeters showed a standard deviation of 4.1% below to the reference values established by international guide lines. The equivalent dose in gonads was 14.27mGy. [Copyright &y& Elsevier]

Abstract: It is well known that paediatric patients are generally at greater risk for the development of cancer per unit of radiation dose compared with adults, due both to the longer life expectancy for any harmful effects of radiation to manifest, and the fact that developing organs and tissues are more sensitive to the effects of radiation. Multiple computed tomography (CT) examinations may cumulatively involve absorbed doses to organs and tissues that can sometimes approach or exceed the levels known from epidemiological studies to significantly increase the probability of cancer development. Radiation protection strategies include rigorous justification of CT examinations and the use of imaging techniques that are non-ionising, followed by optimisation of radiation dose exposure (according to the ‘as low as reasonably achievable’ principle). Special consideration should be given to the availability of dose reduction technology when acquiring CT scanners. Dose reduction should be optimised by adjustment of scan parameters (such as mAs, kVp, and pitch) according to patient weight or age, region scanned, and study indication (e.g. images with greater noise should be accepted if they are of sufficient diagnostic quality). Other strategies include restricting multiphase examination protocols, avoiding overlapping of scan regions, and only scanning the area in question. Newer technologies such as tube current modulation, organ-based dose modulation, and iterative reconstruction should be used when appropriate. Attention should also be paid to optimising study quality (e.g. by image post-processing to facilitate radiological diagnoses and interpretation). Finally, improving awareness through education and advocacy, and further research in paediatric radiological protection are important to help reduce patient dose. [Copyright &y& Elsevier]

Abstract: In 1998, the International Commission on Radiological Protection (ICRP) warned that computed tomography (CT) doses were high, and the frequency of usage was likely to increase in view of spiral CT technology that enhances patient convenience and provides high-quality diagnostic information. Two ICRP publications (Publications 87 and 102) have provided patient dose management recommendations while reviewing the technology and results of optimisations to date, and stimulated interest in patient dose management. The International Atomic Energy Agency, on the other hand, has been instrumental in assessing the state of practice at grassroots level, identifying lacunae in justification and optimisation, providing guidance to counterparts in various countries, and improving practice. The results from approximately 50 less-resourced countries for adult and paediatric CT studies have become available, and some have been published. The concerted efforts and actions by these two international organisations have contributed to better awareness and improvement of patient protection in CT in adults and children in many countries. [Copyright &y& Elsevier]

Computed tomography is an increasingly used imaging modality in childhood. Since pediatric population possess increased radiosensitivity and radiation-related cancer risk is related with cumulative dose, the radiation exposure must be carefully established. Use of the same CT settings for adults and children, deficiency of weight adjusted protocols, lack of consensus for the measurement of dose and related risks of radiation, and absence of penalties for higher doses are essential problems. Radiation dose can significantly be decreased with evaluation of -only-targeted part of the body in appropriate conditions, rearrangement of the scanning parameters for children, and subject based protocol and dose adjustment for each children. The alternations in technical parameters of CT device like tube current, kilovoltage peak, table speed should be well-known and carefully applied for limitation of the radiation dose. [ABSTRACT FROM AUTHOR]

Abstract: Background: The frequent use of computed tomography is a major cause of the increasing medical radiation exposure of the general population. Consequently, dose reduction and radiation protection is a topic of scientific and public concern. Aim: We evaluated the available literature on physicians’ knowledge regarding radiation dosages and risks due to computed tomography. Methods: A systematic review in accordance with the Cochrane and PRISMA statements was performed using eight databases. 3091 references were found. Only primary studies assessing physicians’ knowledge about computed tomography were included. Results: 14 relevant articles were identified, all focussing on dose estimations for CT. Overall, the surveys showed moderate to low knowledge among physicians concerning radiation doses and the involved health risks. However, the surveys varied considerably in conduct and quality. For some countries, more than one survey was available. There was no general trend in knowledge in any country except a slight improvement of knowledge on health risks and radiation doses in two consecutive local German surveys. Conclusions: Knowledge gaps concerning radiation doses and associated health risks among physicians are evident from published research. However, knowledge on radiation doses cannot be interpreted as reliable indicator for good medical practice. [ABSTRACT FROM AUTHOR]

Non-invasive imaging, that leads to early more precise and much less morbid diagnosis, has revolutionized patient management. There is a significant increase in radiation dose from medical procedures using non-invasive imaging, such as computed tomography and nuclear medicine. Minimizing radiation dose without compromising diagnostic quality is obviously key. Self-referral, the fear of litigation, image quality, training, equipment, and to some extent advanced technology, are identified as factors that contribute to increased radiation dose. There is a need to control and minimize health risks, while maximizing the benefits of radiation in medicine as the inappropriate handling of radiation can result in potential health hazards both for patients and staff [1- 21]. [ABSTRACT FROM AUTHOR]

The author reflects on a review of the past effort of improving radiation safety in pediatric radiology. He stresses that the inception of the Society for Pediatric Radiology (SPR) in 1958, pediatric radiologists played a crucial role in radiation protection and awareness. One of this was the first in as series of As Low As Reasonably Achievable (ALARA) conferences sponsored by Dr. Thomas Slovis to discuss Computed tomography (CT) dose reduction in a multidisciplinary format.

Abstract: Choice of imaging modalities should be based on scientific proof and best practice guidelines. However, in the neonatal age group there is a paucity of medical evidence, and imaging is often guided by local experience, availability of equipment and expertise, and by logistical factors. This paper discusses possible indications for CT in the neonate, the associated radiation protection issues, common CT findings and potential pitfalls in technique and image interpretation. Due to the particular range of abnormalities in this age group, imaging must be tailored to the individual, and should in most cases be done in specialist units. [Copyright &y& Elsevier]

This study aimed at assessment of efficacy of selective in-plane shielding in adults by quantitative evaluation of the achieved dose reduction and image quality. Commercially available accessories for in-plane shielding of the eye lens, thyroid and breast, and an anthropomorphic phantom were used for the evaluation of absorbed dose and image quality. Organ dose and total energy imparted were assessed by means of a Monte Carlo technique taking into account tube voltage, tube current, and scanner type. Image quality was quantified as noise in soft tissue. Application of the lens shield reduced dose to the lens by 27% and to the brain by 1%. The thyroid shield reduced thyroid dose by 26%; the breast shield reduced dose to the breasts by 30% and to the lungs by 15%. Total energy imparted (unshielded/shielded) was 88/86 mJ for computed tomography (CT) brain, 64/60 mJ for CT cervical spine, and 289/260 mJ for CT chest scanning. An increase in image noise could be observed in the ranges were bismuth shielding was applied. The observed reduction of organ dose and total energy imparted could be achieved more efficiently by a reduction of tube current. The application of in-plane selective shielding is therefore discouraged. [ABSTRACT FROM AUTHOR]

Purpose: To measure and reduce the patient dose during computed tomography (CT) for dental applications.Material and Methods: Lithium fluoride thermoluminescent dosimeters were implanted in a tissue-equivalent humanoid phantom (Alderson-Rando-Phantom) to determine doses to the thyroid gland, the active bone marrow, the salivary glands, and the eye lens. Dental CT was performed with spiral CT and a dental software package. The usual dental CT technique was compared with a new dose-reduced protocol, which delivered best image quality at lowest possible radiation dose, as tested in a preceding study. Image quality was analysed using a human anatomic head preparation. In addition, the radiation dose was compared with panoramic radiography and digital volume tomography (DVT). Eight radiologists evaluated all images in a blinded fashion. A Wilcoxon rank pair test was used for statistical evaluation.Results: Radiation dose could be reduced by a factor of 9 (max.) with the new dose-reduced protocol (e.g. bone marrow dose from 23.6 mSv to 2.9 mSv; eye lens from 0.5 mSv to 0.3 mSv; thyroid gland from 2.5 mSv to 0.5 mSv; parotid glands from 2.3 mSv to 0.4 mSv). Dose reduction did not reduce image quality or diagnostic information.Conclusion: A considerable dose reduction without loss of diagnostic information is achievable in dental CT. As radiation exposure of the presented low-dose protocol is expected to be in the same range as DVT, low-dose dental CT might be superior to DVT, because CT can be used to evaluate soft tissues as well. [ABSTRACT FROM AUTHOR]

Purpose: To propose national diagnostic reference levels (DRLs) for radiotherapy (RT) computed tomography (CT) localization purposes, compare both CT units used in the largest RT department in the country and to compare gathered results with other published DRLs in order to discover any need of optimization.Methods: In total, 1631 patient data (time spend of 4 months) regarding sex, examination type, total dose-length product (DLP) and CTDIvol was collated on two CT units. Those simulation procedures account for more than 80 % of all simulation procedures performed nationwide. Then, total DLP and CTDIvol was calculated and mean, median and 3rd quartile for both units together were presented to determine national DRLs for simulation procedures. The same data was later compared between both units to discover any potential need for optimization.Results: 3rd quartile values of DLP for abdomen, breast, chest, head, head and neck, pelvis and spine were 1116.2, 606.6, 832.4, 1942.4, 969.2, 677.1 and 1042.4 mGy∙cm, respectively. 3rd quartile CTDIvol values for the same sequence of procedures were 18.7, 13.3, 19.2, 76.9, 22.6, 17.9 and 22.2 mGy, respectively. Among the two units, the mentioned dose values were on average significantly higher on one CT unit than on the other unit.Conclusions: When comparing collected dose values with other studies, RT CT DRLs showed that radiation doses from our institution were similar or even lower. Some variations were found between both CT units in certain protocols, so exposure parameters should be reviewed and optimized. [ABSTRACT FROM AUTHOR]

Purpose: To determine the clinical impact of CT dose management team on radiation exposure and image quality.Methods: 2026 clinical routine CT examinations of 1315 patients were evaluated retrospectively. A CT dose management team was established as an integral part of the radiological department. It identified 5 CT protocols (A-E), where national reference values were exceeded the most. Those reference values included specifically the mean volumetric CT dose index (CTDIvol) and the mean dose-length product (DLP). Baseline data (period 1) and follow up data (period 2) were obtained after reduction of tube voltage and increase of pitch or noise index. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated to compare image quality. Two-sided t-tests were performed.Results: Mean CTDIvol and mean DLP of the chest protocol (A) decreased after reduction of tube voltage (P < 0.01). In the chest/abdomen/pelvis protocol (B), the increase of noise index resulted in a significant mean CTDIvol decrease (P < 0.02) without statistical significance of mean DLP (P < 0.12). In the abdomen/pelvis protocol (C), mean CTDIvol (P = 0.01) and mean DLP (P < 0.01) were significantly lower after noise index increase. In the staging of hepatocellular carcinoma (D), mean CTDIvol and mean DLP were significantly lower after increase of pitch and noise index (P < 0.01). The lung protocol (E) yielded no significant changes after modulation (P > 0.05). SNR (protocol A) was significantly higher in period 2 (P < 0.04). Protocol D showed significantly lower selected SNR and CNR (P < 0.02).Conclusions: Establishing an operating dose management team as a standard for good clinical practice helps to considerably reduce CT radiation dose while preserving image quality. [ABSTRACT FROM AUTHOR]