Spectral CT in patients with acute thoracoabdominal bleeding-a safe technique to improve diagnostic confidence and reduce dose?

Computed tomography (CT) protocols for the detection of bleeding sources often include unenhanced CT series to distinguish contrast agent extravasation from calcification. This study evaluates whether virtual non-contrast images (VNC) can safely replace real non-contrast images (RNC) in the search for acute thoracoabdominal bleeding and whether monoenergetic imaging can improve the detection of the bleeding source.The 32 patients with active bleeding in spectral CT angiography (SCT) were retrospectively analyzed. RNC and SCT series were acquired including VNC and monoenergetic images at 40, 70, and 140 keV. CT numbers were measured in regions of interest (ROIs) in different organs and in the bleeding jet for quantitative image analysis (contrast-to-noise ratios [CNR] and signal-to-noise ratio [SNR]). Additionally, 2 radiologists rated detectability of the bleeding source in the different CT series. Wilcoxon rank test for related samples was used.VNC series suppressed iodine sufficiently but not completely (CT number of aorta: RNC: 33.3±12.3, VNC: 44.8 ±â€Š9.5, P = .01; bleeding jet: RNC: 43.1 ±â€Š16.9, VNC: 56.3 ±â€Š16.7, P = .02). VNC showed significantly higher signal-to-noise ratios than RNC for all regions investigated. Contrast-to-noise ratios in the bleeding jet were significantly higher in 40 keV images than in standard 140 keV images. The 40 keV images were also assigned the best subjective ratings for bleeding source detection.VNC can safely replace RNC in a CT protocol used to search for bleeding sources, thereby reducing radiation exposure by 30%. Low-keV series may enhance diagnostic confidence in the detection of bleeding sources.

Practical recommendations for the application of DE 59/2013.

The changes introduced with Council Directive 2013/59/Euratom will require European Member States adapt their regulations, procedures and equipment to the new high standards of radiation safety. These new requirements will have an impact, in particular, on the radiology community (including medical physics experts) and on industry. Relevant changes include new definitions, a new dose limit for the eye lens, non-medical imaging exposures, procedures in asymptomatic individuals, the use and regular review of diagnostic reference levels (including interventional procedures), dosimetric information in imaging systems and its transfer to the examination report, new requirements on responsibilities, the registry and analysis of accidental or unintended exposure and population dose evaluation (based on age and gender distribution). Furthermore, the Directive emphasises the need for justification of medical exposure (including asymptomatic individuals), introduces requirements concerning patient information and strengthens those for recording and reporting doses from radiological procedures, the use of diagnostic reference levels, the availability of dose-indicating devices and the improved role and support of the medical physics experts in imaging.

Physicians' Perceptions of Radiation Dose Quantity Depend on the Language in Which It Is Expressed.

PURPOSE: Radiation dose information is increasingly requested by nonradiology providers, but there are no standard methods for communicating dose. The aim of this study was to compare physicians' perceptions of the amount of radiation associated with similar dose quantities expressed using different dose terms to evaluate the impact of word choice on physicians' understanding of radiation dose. METHODS: Internal medicine and pediatric residents were surveyed online for 42 days. After obtaining demographics and training levels, respondents were asked to rank five different radiation dose quantities, each corresponding to one of the five ACR relative radiation levels (RRLs) expressed using different dose terms. Respondents ranked the choices from least to greatest (ie, from 1 to 5) or indicated if all five were equal. For the final question, the same dose quantity was expressed five different ways. RESULTS: Fifty-one medicine and 45 pediatric residents responded (a 44% response rate). Mean differences in rankings were as follows: for chest x-rays, 0.109 (95% confidence interval [CI], -0.018 to 0.236); for cross-country flights, 0.462 (95% CI, 0.338 to 0.585); for natural background radiation, -0.672 (95% CI, -0.793 to -0.551); for cancer risk, -0.294 (95% CI, -0.409 to -0.178); and for ACR RRL, 0.239 (95% CI, 0.148 to 0.329). Statistically significant differences were found in the distributions of rankings (P < .001) and percentage of correct rankings across each radiation dose term (P < .001), with the ACR RRL having the highest percentage of correct rankings (61.2%). CONCLUSIONS: Adult and pediatric physicians consistently over- or underestimated radiation dose quantities using different terms to express radiation dose. These results suggest that radiation dose information should be communicated using standard terminology such as the ACR RRL scale to foster consistency and improve the accuracy of physicians' radiation risk perceptions.

Improving Radiation Awareness and Feeling of Personal Security of Non-Radiological Medical Staff by Implementing a Traffic Light System in Computed Tomography.

PURPOSE: Non-radiological medical professionals often need to remain in the scanning room during computed tomography (CT) examinations to supervise patients in critical condition. Independent of protective devices, their position significantly influences the radiation dose they receive. The purpose of this study was to assess if a traffic light system indicating areas of different radiation exposure improves non-radiological medical staff's radiation awareness and feeling of personal security. MATERIAL AND METHODS: Phantom measurements were performed to define areas of different dose rates and colored stickers were applied on the floor according to a traffic light system: green = lowest, orange = intermediate, and red = highest possible radiation exposure. Non-radiological medical professionals with different years of working experience evaluated the system using a structured questionnaire. Kruskal-Wallis and Spearman's correlation test were applied for statistical analysis. RESULTS: Fifty-six subjects (30 physicians, 26 nursing staff) took part in this prospective study. Overall rating of the system was very good, and almost all professionals tried to stand in the green stickers during the scan. The system significantly increased radiation awareness and feeling of personal protection particularly in staff with ≤ 5 years of working experience (p < 0.05). The majority of non-radiological medical professionals stated that staying in the green stickers and patient care would be compatible. Knowledge of radiation protection was poor in all groups, especially among entry-level employees (p < 0.05). CONCLUSION: A traffic light system in the CT scanning room indicating areas with lowest, intermediate, and highest possible radiation exposure is much appreciated. It increases radiation awareness, improves the sense of personal radiation protection, and may support endeavors to lower occupational radiation exposure, although the best radiation protection always is to re-main outside the CT room during the scan. KEY POINTS: • A traffic light system indicating areas with different radiation exposure within the computed tomography scanner room is much appreciated by non-radiological medical staff. • The traffic light system increases non-radiological medical staff's radiation awareness and feeling of personal protection. • Knowledge on radiation protection was poor in non-radiological medical staff, especially in those with few working experience.