Investigation of a potential upstream harmonization based on image appearance matching to improve radiomics features robustness: a phantom study.

Objective. Radiomics is a promising valuable analysis tool consisting in extracting quantitative information from medical images. However, the extracted radiomics features are too sensitive to variations in used image acquisition and reconstruction parameters. This limited robustness hinders the generalizable validity of radiomics-assisted models. Our aim is to investigate a possible harmonization strategy based on matching image quality to improve feature robustness.Approach.We acquired CT scans of a phantom with two scanners across different dose levels and percentages of Iterative Reconstruction algorithms. The detectability index was used as a comprehensive task-based image quality metric. A statistical analysis based on the Intraclass Correlation Coefficient was performed to determine if matching image quality/appearance could enhance the robustness of radiomics features extracted from the phantom images. Additionally, an Artificial Neural Network was trained on these features to automatically classify the scanner used for image acquisition.Main results.We found that the ICC of the features across protocols providing a similar detectability index improves with respect to the ICC of the features across protocols providing a different detectability index. This improvement was particularly noticeable in features relevant for distinguishing between scanners.Significance.This preliminary study demonstrates that a harmonization based on image quality/appearance matching could improve radiomics features robustness and heterogeneous protocols can be used to obtain a similar image appearance in terms of the detectability index. Thus protocols with a lower dose level could be selected to reduce the amount of radiation dose delivered to the patient and simultaneously obtain a more robust quantitative analysis.

Assessing the radiological impact of radiation exposure devices.

Radiation exposure devices (REDs) are radiological weapons obtained by concealing a strong gamma-emitting source in a place frequented by public to cause radiation injuries following the absorption of elevated radiation doses. The present work aims to assess the radiological impact of an RED by simulating its effects in both dynamical and static conditions of the covertly exposed population, with individual position and motion obtained through a Monte Carlo approach. The results indicate that in small enclosures the motion of people amplify the effects of radiation exposure with respect to the static case because it turns out in a larger number of individuals receiving doses above the threshold for the onset of deterministic effects. This behavior is mitigated in medium and large enclosures due to dose spreading over trajectories moving far away from the critical region close to the RED. The scaling laws obtained with a simple circular geometry were successfully applied to a more complex geometry like that of a stadium. The potentially large number of victims and the possibility to reiterate the attack raise the question of early detection. This can be achieved either by radiation survey or by indirectly inferring the presence of a strong radioactive source following the triage of patients with radiation sickness symptoms collected by the same hospital. In the former case careful design and operation of aerial or in situ monitoring is needed, while in the latter specific training should be given to healthcare personnel aimed to improve their discrimination and cooperation capabilities.

Ranking nuclear and radiological terrorism scenarios: the Italian case.

A quantitative criterion for ranking the different scenarios of nuclear and radiological terrorism has been developed. The aim of the model is not to predict terroristic events but only to indicate which scenario has the higher utility from the point of view of a terroristic organization in terms of balance between factors favoring and discouraging the attack, respectively. All these factors were quantified according to a scoring system that takes into account the logarithmic relationship between perceptions and stimuli. The criterion was applied to several scenarios, each of which was modeled in a simple but not trivial way in order to estimate the expected damage in terms of probable life losses from both radiative and nonradiative effects. The outcome from the ranking method indicates that the attractive scenario appears to be the detonation of a low yield improvised nuclear device in the metropolitan area of a major city.

Quality index of radiological devices: results of one year of use.

PURPOSE: The physical quality index (QI) of radiological devices summarises in a single numerical value between 0 and 1 the results of constancy tests. The aim of this paper is to illustrate the results of the use of such an index on all public radiological devices in the Livorno province over one year. MATERIALS AND METHODS: The quality index was calculated for 82 radiological devices of a wide range of types by implementing its algorithm in a spreadsheet-based software for the automatic handling of quality control data. RESULTS AND DISCUSSION: The distribution of quality index values was computed together with the associated statistical quantities. This distribution is strongly asymmetrical, with a sharp peak near the highest QI values. The mean quality index values for the different types of device show some inhomogeneity: in particular, mammography and panoramic dental radiography devices show far lower quality than other devices. In addition, our analysis has identified the parameters that most frequently do not pass the quality tests for each type of device. Finally, we sought some correlation between quality and age of the device, but this was poorly significant. CONCLUSIONS: The quality index proved to be a useful tool providing an overview of the physical conditions of radiological devices. By selecting adequate QI threshold values for, it also helps to decide whether a given device should be upgraded or replaced. The identification of critical parameters for each type of device may be used to improve the definition of the QI by attributing greater weights to critical parameters, so as to better address the maintenance of radiological devices.