Paediatric Computed Tomography Examinations Research Articles

A comparison of Saudi Arabian and Australian radiographers' perceptions of computed tomography radiation dose

AbstractBackground: Computed tomography (CT) is a powerful diagnostic tool, but the radiation delivered to paediatric patients needs to be kept to a minimum. Thus, CT education and protocols must be continuously reviewed, particularly with respect to paediatric CT examinations. Purpose: To investigate the knowledge and perceptions of paediatric CT radiographers from Australia and Saudi Arabia regarding paediatric CT dose. Methods: Interviews were conducted with CT radiographers working in dedicated paediatric hospitals during 2010. Their training and perceptions of paediatric CT radiation dose were evaluated, along with their departments' policies. Actual dose measurements from their departments were compared to their perceptions to reveal radiographers' awareness of their department's typical dose relative to those delivered by their contemporaries. Results: Almost all surveyed radiographers were willing to minimise their radiation dose, but many Saudi Arabian radiographers were not allowed to make any changes to their CT protocols. CT protocols in Saudi Arabia were wholly defined by the CT machine vendors' recommendations, whereas most Australian CT protocols were established following reviews of the appropriate literature. Conclusion: Australian and Saudi Arabian CT radiographers' training and perceptions of paediatric CT dose vary substantially, and differences exist in terms of workplace culture. Continuous professional development will assist Saudi Arabian radiographers to reduce CT radiation dose.

Radiation dose in paediatric computed tomography: risks and benefits.

Computed tomography (CT) is a powerful tool for the accurate and effective diagnosis and treatment of a variety of conditions because it allows high-resolution three-dimensional images to be acquired very quickly. However as the number of CT procedures performed globally have continued to increase; with growing concerns about patient protection. Currently, no system is in place to track patient doses and the lifetime cumulative dose from medical sources. The widespread use of CT even in developing countries has raised questions regarding the possible threat to public health especially in children. The best available risk estimates suggest that paediatric CT will result in significantly increased lifetime radiation risk over adult CT. Studies have shown that lower milliampere-second (mAs) settings can be used for children without significant loss of information. Although the risk-benefit balance is still strongly tilted toward benefit, there is still need for caution. Furthermore since the frequency of paediatric CT examinations is rapidly increasing, and estimates suggest that quantitative lifetime radiation risks for children are not negligible, efforts should be made toward more active reduction of CT exposure settings in paediatric patients. This article hopes to address this concerns and draw attention to the fact that children are not 'small adults ' and should therefore be treated differently.

Differences in using the international commission on radiological protection’s publications 60 and 103 for determining effective dose in paediatric CT examinations

Abstract The use of computed tomography (CT) worldwide is continuing to increase for both adults and children, posing population health risks due to radiation exposure. These risks are highest for children, reducing with age at exposure. Effective dose is a useful parameter for expressing relative risk and comparing dose. In this study, high sensitivity thermoluminescence dosemeters (TLD) were used to measure organ absorbed doses and to calculate effective dose for paediatric CT examinations of the brain, chest and abdomen/pelvis. Formalisms recommended by the International Commission on Radiological Protection (ICRP) in Publications 60 and 103 were assessed. The effective dose computed using ICRP 103 was 22% lower for a CT brain examination, 16% higher for a CT chest examination and 4% lower for a CT abdomen/pelvis examination when compared with the effective dose computed using ICRP 60. These values were compared with effective dose calculated using a dose length product (DLP) conversion method. The DLP derived effective doses were within 30% of the TLD derived effective doses. In summary, the effective dose varies depending on the ICRP definition used, predominantly due to changes in tissue weighting factors. Furthermore, the DLP conversion method is relatively reliable for approximating effective dose and easy to use.

Survey of practice in paediatric computed tomography

The purpose of this study was to explore the frequency of paediatric computed tomography (CT) examinations in several hospitals in Bulgaria and to assess the current practice. The standard forms provided by the International Atomic Emergency Agency for survey of the paediatric CT practice were used. Six hospitals provided data on frequency of paediatric CT examinations performed in 2009. Large variations in dose, up to a factor of 4, were found among the centres within the same age group for a given procedure, and in one of the hospitals the paediatric dose was twice higher than the adult dose. Seven departments use dedicated CT protocols for children. Only 4 in 12 departments keep records of patient dose. Dose information for previous examinations is not required by the radiologists. The collected detailed data provided preliminary information how the patient doses in paediatric CT can be reduced. Recommendations were given based on the findings.

Assessment of effective dose in paediatric CT examinations

Current concerns focus on the high doses encountered in computed tomography (CT) examinations as they are extending towards younger and more radiosensitive patients. Previous work produced conversion coefficients for effective dose (E) from dose-length product (DLP) for four anatomical body regions applicable to any patient size. This work aims to update the earlier work, incorporating the new ICRP 2007 tissue-weighting factors and testing the methodology on modern scanners. For each age and body region, E was determined relative to DLP. Measurements were carried out on a 64-slice scanner to test this methodology. The conversion coefficients show exponential decrease with patient size. Conversion factors for the pelvis region are lower than before (30-40 %), those for the chest increased (by up to 25 %) whereas those for the head and abdomen remained fairly similar. Application of the coefficients to modern scanners verified the results, so that this methodology can be applied for a wide range of paediatric CT examinations.

The Predicted Increased Cancer Risk Associated With a Single Computed Tomography Examination for Calculus Detection in Pediatric Patients Compared With the Natural Cancer Incidence

The objective of the study was to estimate the increased lifetime cancer risk associated with a single computed tomography (CT) examination for calculus detection in pediatric patients and compare it with the lifetime natural cancer risk. We used the program CT-Expo to calculate the radiation doses to various abdominal and pelvic organs for age-appropriate pediatric renal stone CT examination protocols used at our institution. Using the Biological Effects of Ionizing Radiation (BEIR) VII report, we estimated the lifelong cancer risk for these organs and compared it with the natural cancer risk for the same organs as predicted by the Surveillance, Epidemiology and End Results data from the National Cancer Institute. For children 10 years or younger at the time of the examination, about 3 radiation-induced cancers are predicted for every 1000 naturally occurring cancers, and for children 15 years old, about 2 radiation-induced cancers are predicted for every 1000 naturally occurring cancers. The radiation dose from this examination is approximately equivalent to 1 to 2 years of background radiation. The ratio of the risk for any abdominal and pelvic cancer due to a single CT examination for calculus detection to the risk of a naturally occurring cancer over the lifetime of a child is estimated to be 2/1000 to 3/1000. With this information, the emergency department pediatrician can more effectively counsel parents about the risk-benefit aspects of the CT examination for renal calculus disease in their children.

Evaluation of Dose Reduction and Image Quality in Pediatric Multi-Detector CT

The number of CT (computed tomography) examinations in the diagnosis field has increased, and X-ray exposure to patients has also continued to increase. As the number of CT examinations is increasing in the general population, the number of pediatric CT examinations is rapidly increasing as well. The radiation dose from CT for pediatric patients remains a major concern because the risk related to ionizing radiations is higher in children than in adults. The purpose of this study was to evaluate radiation dose, image noise, and image contrast as a function of tube voltage (kVp) and tube current (mAs) in dierent phantoms, which were intended to simulate abdominal size, and to provide guidance on dose reduction on the basis of patient dimensions, as well as technical parameters. In this study, MDCT (multi-detector computed tomography) was used as an X-ray generator, and PMMA (polymethylmethacrylate) phantoms were used in all experiments. PMMA phantom diameters were 10 cm, 16 cm, and 32 cm corresponding to newborn, age 5, and adult abdominal sizes, respectively. To evaluate radiation dose, the CTDIw (weighted CT dose index) was calculated from the CTDI measured using ion chamber, and to evaluate image quality, image noise and image contrast were measured from a scanned image. Finally, the CNRD (dose-weighted contrast-to-noise ratio) was calculated from the radiation dose, image noise, and image contrast to optimize the technical factors. The radiation dose increased as a function of kVp and mAs and decreased as a function of the phantom diameter. Especially, for increasing tube voltage from 80 to 140 kVp, there were 395.08% and 448.27% increases in radiation dose for 10 cm and 32 cm PMMA phantoms, respectively. The image noise decreased as a function of kVp and mAs and increased as a function of the phantom diameter. And, the image contrast decreased as a function of kVp and phantom diameter and remained fixed as a function of mAs. The values of the CNRD were maximum at 80 kVp for all three phantoms. The results of this study show that it is possible to reduce radiation dose and maintain image quality through the use of lower technical factors (kVp and mAs) for small-sized phantom corresponding to pediatric patients and to provide guidance on radiation dose reduction on the basis of the patient’s dimensions.

Paediatric CT examinations in 19 developing countries: frequency and radiation dose

The aims of this study were to investigate the frequency of computed tomography (CT) examinations for paediatric patients below 15 y of age in 128 CT facilities in 28 developing countries of Africa, Asia and Eastern Europe and to assess the magnitude of CT doses. Radiation dose data were available from 101 CT facilities in 19 countries. The dose assessment was performed in terms of weighted CT dose index (CTDI(w)), volume CT index and dose length product (DLP) for chest, chest (high resolution), lumbar spine, abdomen and pelvis CT examinations using standard methods. The results show that on average the frequency of paediatric CT examinations was 20, 16 and 5 % of all CT examinations in participating centres in Africa, Asia and Eastern Europe, respectively. Eleven CT facilities in six countries were found to use adult CT exposure parameters for paediatric patients, thus indicating limited awareness and the need for optimisation. CT images were of adequate quality for diagnosis. The CTDI(w) variations ranged up to a factor of 55 (Africa), 16.3 (Asia) and 6.6 (Eastern Europe). The corresponding DLP variations ranged by a factor of 10, 20 and 8, respectively. Generally, the CTDI(w) and DLP values in Japan are lower than the corresponding values in the three regions in this study. The study has indicated a stronger need in many developing countries to justify CT examinations in children and their optimisation. Awareness, training and monitoring of radiation doses is needed as a way forwards.

Dose distribution in pediatric CT head examination using a new phantom with radiochromic film

Performing a detailed dose measurement is important to keep radiation doses during computed tomography (CT) examinations as low as reasonably achievable. To estimate in detail the dose distribution during pediatric CT examination of the head, a sheet roll CT dosimetry phantom (SRCT-P) with radiochromic film (RF) was developed. The dose distributions in the SRCT-P (diameters of 6 [premature baby], 10 [neonate], and 14 [infant] cm) were evaluated. The SRCT-Ps were made by rolling up flexible acrylic sheets (1.1 g/cm3). RFs were positioned every 5 mm along the radius at each SRCT-P, starting at 10 mm (center) and ending on the surface. The dose distribution along the z-axis at the center or on the surface showed a flat or wave pattern, respectively. When the mean surface dose at 10 cm diameter was taken as 100%, the mean surface doses at 6 or 14 cm diameters were 105 or 96%, respectively, and the mean center doses at 6, 10, and 14 cm were 109, 99, and 74%, respectively. The maximum-minimum doses and dose distribution of a CT examination can be measured separately by using the SRCT-P with RF.