Effective and organ doses in patient undergoing interventional neuroradiology procedures: A multicentre study.

PURPOSE: Radiation doses to adult patients submitted to cerebral angiography and intracranial aneurysms treatments were assessed by using DICOM Radiation Dose Structured Reports (RDSR) and Monte Carlo simulations. Conversion factors to estimate effective and organ doses from Kerma-Area Product (PKA) values were determined. METHODS: 77 cerebral procedures performed with five angiographic equipment installed in three Italian centres were analyzed. Local settings and acquisition protocols were considered. The geometrical, technical and dosimetric data of 16,244 irradiation events (13305 fluoroscopy, 2811 digital subtraction angiography, 128 cone-beam CT) were extracted from RDSRs by local dose monitoring systems and were input in MonteCarlo PCXMC software to calculate effective and organ doses. Finally, conversion factors to determine effective and organ doses from PKA were determined. Differences between centres were assessed through statistical analysis and accuracy of dose calculation method based on conversion factors was assessed through Bland-Altman analysis. RESULTS: Large variations in PKA (14-561 Gycm2) and effective dose (1.2-73.5 mSv) were observed due to different degrees of complexity in the procedures and angiographic system technology. The most exposed organs were brain, salivary glands, oral mucosa, thyroid and skeleton. The study highlights the importance of recent technology in reducing patient exposure (about fourfold, even more in DSA). No statistically significant difference was observed in conversion factors between centres, except for some organs. A conversion factor of 0.09 ± 0.02 mSv/Gycm2 was obtained for effective dose. CONCLUSIONS: Organ and effective doses were assessed for neuro-interventional procedures. Conversion factors for calculating effective and organ doses from PKA were provided.

Statement of the Italian Association of Medical Physics (AIFM) task group on radiation dose monitoring systems.

The evaluation of radiation burden in vivo is crucial in modern radiology as stated also in the European Directive 2013/59/Euratom-Basic Safety Standard. Although radiation dose monitoring can impact the justification and optimization of radiological procedure, as well as effective patient communication, standardization of radiation monitoring software is far to be achieved. Toward this goal, the Italian Association of Medical Physics (AIFM) published a report describing the state of the art and standard guidelines in radiation dose monitoring system quality assurance. This article reports the AIFM statement about radiation dose monitoring systems (RDMSs) summarizing the different critical points of the systems related to Medical Physicist Expert (MPE) activities before, during, and after their clinical implementation. In particular, the article describes the general aspects of radiation dose data management, radiation dose monitoring systems, data integrity, and data responsibilities. Furthermore, the acceptance tests that need to be implemented and the most relevant dosimetric data for each radiological modalities are reported under the MPE responsibility.

Juvenile Angiofibroma: What Is on Stage?

OBJECTIVES/HYPOTHESIS: The aim of the present study is to validate and compare four of the most widely used staging systems for juvenile angiofibroma on a homogeneous cohort of patients. STUDY DESIGN: Retrospective case series. METHODS: A retrospective review of patients treated with endoscopic or endoscopic-assisted surgical resection between 1999 and 2020 was carried out. Each case was classified according to the following staging systems: Andrews-Fisch (1989), Radkowski (1996), University of Pittsburgh Medical Center (2010), and Janakiram (2017). Spearman's rank correlation test and areas under the curve of receiver operator curves were used to assess the correlation between outcomes of interests (blood loss, surgical time, need for transfusion, and persistence of disease) and stage of disease. RESULTS: Seventy-nine patients were included, with a median follow-up time of 25 months (range 12-127 months). Median surgical time was 217 minutes (range 52-625). Median blood loss was 500 mL (range 40-5200) and 27 patients (34.2%) required blood transfusions. Seven patients (8.9%) showed persistence of disease. All classification systems showed a similar association with blood loss, surgical time, persistence of disease, and need for transfusion. CONCLUSIONS: Involvement of the infratemporal fossa and intracranial extension was identified as red flags for surgical planning and preoperative counseling, as associated with increased risk for transfusion and persistent/recurrent disease, respectively. No classification system was found to be better than the others in predicting the most important outcomes. Therefore, the simplest and most easily applicable system would be the preferred one to be used in clinical practice. LEVEL OF EVIDENCE: 4 Laryngoscope, 132:1160-1165, 2022.

A single phantom, a single statistical method for low-contrast detectability assessment.

PURPOSE: The assessment of low-contrast-details is a part of the quality control (QC) program in digital radiology. It generally consists of evaluating the threshold contrast (Cth) detectability details for different-sized inserts, appropriately located in dedicated QC test tools. This work aims to propose a simplified method, based on a statistical model approach for threshold contrast estimation, suitable for different modalities in digital radiology. METHODS: A home-madelow-contrast phantom, made of a central aluminium insert with a step-wedge, was assembled and tested. The reliability and robustness of the method were investigated for Mammography, Digital Radiography, Fluoroscopy and Angiography. Imageswere analysed using our dedicated software developed on Matlab®. TheCth is expressed in the same unit (mmAl) for all studied modalities. RESULTS: This method allows the collection of Cthinformation from different modalities and equipment by different vendors, and it could be used to define typical values. Results are summarized in detail. For 0.5 diameter detail, Cthresults are in the range of: 0.018-0.023 mmAl for 2D mammography and 0.26-0.34 mmAl DR images. For angiographic images, for 2.5 mm diameter detail, the Cths median values are 0.55, 0.4, 0.06, 0.12 mmAl for low dose fluoroscopy, coronary fluorography, cerebral and abdominal DSA, respectively. CONCLUSIONS: The statistical method proposed in this study gives a simple approach for Low-Contrast-Details assessment, and the typical values proposed can be implemented in a QA program for digital radiology modalities.

Patient dose in angiographic interventional procedures: A multicentre study in Italy.

PURPOSE: The Council Directive 2013/59/EURATOM considers interventional radiology to be a special practice involving high doses of radiation and requiring strict monitoring to ensure the best quality assurance programs. This work reports the early experience of managing dose data from patients undergoing angiography in a multicentre study. MATERIALS AND METHODS: The study was based on a survey of about 15,200 sample procedures performed in 21 Italian hospitals centres involved on a voluntary basis. The survey concerned the collection of data related to different interventional radiology procedures: interventional cardiology, radiology, neuroradiology, vascular surgery, urology, endoscopy and pain therapy from a C-Arm and fixed units. The analysis included 11 types of procedures and for each procedure, air-kerma, kerma-area product and fluoroscopy time were collected. RESULTS: The duration and dose values of fluoroscopic exposure for each procedure is strongly dependent on individual clinical circumstances including the complexity of the procedure; the observed distribution of patient doses was very wide, even for a specified protocol. The median values of the parameters were compared with the diagnostic reference levels (DRL) proposed for some procedures in Italy (ISTISAN) or internationally. This work proposes local DRL values for three procedures. CONCLUSION: This first data collection serves to take stock of the situation on patient's dosimetry in several sectors and is the starting point for obtaining and updating DRL recalling that these levels are dependent on experience and technology available.

Endovascular Treatment of Acute Basilar Artery Occlusion: Registro Endovascolare Lombardo Occlusione Basilar Artery (RELOBA) Study Group Experience.

BACKGROUND: Acute basilar artery occlusion (BAO) is considered among the most severe medical emergencies, with very high morbidity and mortality. The aims of this study are to present 5 years experience of 12 centers in Lombardy region on BAO endovascular treatment and to evaluate prognostic factors that may improve clinical outcomes and recanalization rates. MATERIALS AND METHODS: Registro Endovascolare Lombardo Occlusione Basilar Artery (RELOBA) registry is a retrospective multicentric collection of patients with acute BAO who underwent endovascular treatment between 2010 and 2015. A total of 102 patients (mean age 65 years) were included. Clinical, procedural, and neuroradiological data were collected. Angiographic results (Treatment in Cerebral Ischemia scale [TICI] score 2b-3) were assessed by each center's interventional neuroradiologist. Good clinical outcome was considered as a modified Rankin Scale score ranging between 0 and 2 in a 3-month follow-up. RESULTS: Thirty-nine percent of patients showed good clinical outcome at 3 months. Mortality rate was 30%. TICI 2b-3 was achieved in 62% of patients. Univariate analysis showed that age, National Institutes of Health Stroke Scale (NIHSS) at onset, time to recanalization, and TICI score were all statistically significant clinical outcome predictors (P < .05). Multivariate logistic regression showed that time to recanalization, age, and NIHSS at onset were significant independent predictors of good outcome. CONCLUSIONS: BAO treatment needs more efforts to assure patients better clinical outcomes. Mechanical thrombectomy is feasible and effective in patients with acute BAO. These results must be confirmed by further prospective studies within randomized controlled settings.

A Quantitative Method for the Evaluation of Spatial Resolution in Quality Control of B-mode Ultrasound Images.

The work describes a method to quantitatively evaluate spatial resolution in B-mode quality control images as radial modulation transfer function (MTF). The method is easy to use in in-field quality assurance programs in clinical institutions, as it is fast and can be performed with the help of phantoms that are already used for routine quality control. It uses a round insert with different echogenic characteristics compared with the phantom background. The method was automated with a MATLAB® routine, which can be run in full automatic mode or with a grade of interaction by the user, as is sometimes necessary with low-quality images. Radial MTF was evaluated for several ultrasound (US) images produced with different clinical US scanners from various vendors and equipped with different types of transducers (linear, convex, sector, vector) working at various frequencies (from 2 to 14 MHz) and with different modalities. It was also evaluated on various computed tomography (CT) images including round inserts. This was done to compare these results with the MTF calculated from the same images using the well-known method from the point spread function (PSF) of a high-contrast bead. Our radial MTF method, adapted to the specific characteristics of US images, was found to be reasonably robust and in line with other methods commonly used for USs (e.g., the pin method, which has repeatability issues) and in other fields, such as X-ray CT.

Role of low dose CT angiography in the follow-up after endovascular aneurysm repair of abdominal aorta.

BACKGROUND: Computed tomography angiography (CTA) is the most employed modality in the follow-up after endovascular aneurysm repair (EVAR) of abdominal aorta (AA); repeated standard controls expose patients to a high cumulative radiation dose (RD). PURPOSE: To compare image quality and RD between 100 kV and 120 kV protocols in the same group of patients, previously treated with EVAR. MATERIAL AND METHODS: Thirty patients, who had performed a previous CTA at 120 kV, underwent a low dose CTA with the same 64-detector machine. Images were evaluated qualitatively and quantitatively. The influence of body mass index (BMI), considering three groups of patients (normal weight, overweight, and obese) was also assessed. RD values (volume CT dose index and effective dose) were calculated. RESULTS: The mean qualitative score at 100 kV was worse than that at 120 kV, but the difference was not statistically significant and in all cases the image quality was satisfactory. At 100 kV the vessels mean attenuation value was significantly higher; signal-to-noise ratio significantly lower; contrast-to-noise ratio lower, but the difference was not significant. Regarding BMI, the difference in the qualitative score was significant in the obese group, but not in the other two groups; of the quantitative parameters only the signal-to-noise ratio presented a significant difference in the obese group. The average CTDIvol was reduced by 22% and the mean effective dose by 36% with the 100 kV protocol compared to the 120 kV protocol. Both differences were significant. CONCLUSION: The 100 kV protocol allowed a consistent RD reduction, maintaining a satisfactory image quality in all patients.

Functional magnetic resonance imaging: comparison between activation maps and computation pipelines in a clinical context.

In this study new evaluation strategies for comparing different Statistical Parametric Maps computed from fMRI time-series analysis software tools are proposed. The aim of our work is to assess and quantitatively evaluate the statistical agreement of activation maps. Some pre-processing steps are necessary to compare SPMs (Statistical Parametric Maps), including segmentation and co-registration. The study of the statistical agreement is carried out following two ways. The first way considers SPMs as the result of two classification processes and extracts confusion matrix and Cohen's kappa index to assess agreement. Some considerations will be made on the statistical dependence of classes and a new formulation of kappa index will be used for overcoming this problem. The second way considers SPMs as two 3D images, and computes the similarity of SPMs images with a fuzzy formulation of the Jaccard Index. Several experiments were conducted both to assess the performance of the proposed evaluation tools and to compare activation maps computation pipelines from two widely used software tools in a clinical context.

The HML's new voxel phantoms: two human males, one human female, and two male canines.

The Human Monitoring Laboratory (HML) has created five new voxel phantoms that can be used for Monte Carlo simulations. Three phantoms were created from computer tomography image sets that were obtained from facilities in Italy and the USA: a human male and the male canines. Two other phantoms were constructed from commercially available software that is used to demonstrate human anatomical features: a human male and a human female. All the voxel phantoms created by the HML that are described in this note are available at no cost to interested researchers.

Performance assessment of four 64-slice computed tomographic devices for a typical clinical protocol.

OBJECTIVE: To compare the performances of four 64-slice CT devices, as regards radiation dose and image quality. METHODS: Effective dose was measured with thermoluminescent dosimeters in an Alderson Rando phantom (Alderson Research Laboratories, New York, NY). Quantitative image quality was evaluated in a Catphan 600 phantom (The Phantom Laboratory, New York, NY) using 3 parameters (modulation transfer function, contrast-to-noise ratio, and figure of merit). Effective and main organ doses were measured in 40 patients (10 for each CT device), who underwent an abdominal study with the same standard protocol; moreover, in these patients, clinical image quality, using a 5-grade quality score, was assessed. RESULTS: In-phantom measured doses and quantitative image quality showed some differences among the 4 devices. On the contrary, effective and organ doses provided to the patients were similar; no statistically significant differences were found also for clinical image quality. CONCLUSIONS: Some differences were found among the 4 devices from a physical point of view; on the other hand, the patient data were similar.