Patient dose in brain perfusion imaging using an 80-slice CT system.

BACKGROUND AND PURPOSE: Brain CT Perfusion (CTP) is an X-ray imaging technique for the assessment of brain tissue perfusion, which can be used in several different entities. The aim of this study is the evaluation of the radiation dose to patients during a comprehensive brain CT prescription protocol (CPP) consisting of an unenhanced brain CT, a brain CT angiography and a CTP scan. MATERIALS AND METHODS: Eighteen patients were studied using an 80-slice CT system, with an iterative reconstruction algorithm. The volume Computed Tomography Dose Index (CTDIvol) and dose length product (DLP) were recorded from the dose report of the system. The calculation of effective dose (ED) was accomplished using the DLP values. RESULTS: For the CTP examinations, the CTDIvol ranged from 116.0 to 134.8mGy, with the mean value 119.5mGy. The DLP ranged from 463.9 to 539.2mGy·cm, with the mean value 478mGy·cm. For the CPP, the total ED ranged from 3.31 to 5.07mSv, with the mean value 4.37mSv. CONCLUSIONS: These values are lower than the values reported in corresponding studies, including studies utilizing CT systems with more slices.

Hysterosalpingography using a flat panel unit: evaluation and optimization of ovarian radiation dose.

PURPOSE: The aim of the present study was the evaluation and optimization of radiation dose to the ovaries (D) in hysterosalpingography (HSG). METHODS: The study included a phantom study and a clinical one. In the phantom study, we evaluated imaging results for different geometrical setups and irradiation conditions. In the clinical study, 34 women were assigned into three different fluoroscopy modes and D was estimated with direct cervical TLD measurements. RESULTS: In the phantom study, we used a source-to-image-distance (SID) of 110 cm and a field diagonal of 48 cm, and thus decreased air KERMA rate (KR) by 19% and 70%, respectively, for beam filtration: 4 mm Al and 0.9 mm Cu (Low dose). The least radiation exposure was accomplished by using the 3.75 pps fluoroscopy mode in conjunction with beam filtration: Low dose. In the clinical study, D normalized to 50 s of fluoroscopy time with a 3.75 pps fluoroscopy mode reached a value of 0.45 ± 0.04 mGy. Observers' evaluation of diagnostic image quality did not significantly differ for the three different modes of acquisition that were compared. CONCLUSIONS: Digital spot radiographs could be omitted in modern flat panel systems during HSG. Fluoroscopy image acquisitions in a modern flat panel unit at 3.75 pps and a beam filtration of 4 mm Al and 0.9 mm Cu demonstrate acceptable image quality with an average D equal to 0.45 mGy. This value is lower compared to the studied literature. For these reasons, the proposed method may be recommended for routine HSG examination in order to limit radiation exposure to the ovaries.

Quantitative assessment of microcalcification cluster image quality in digital breast tomosynthesis, 2-dimensional and synthetic mammography.

Quantitative assessment of microcalcification (MC) cluster image quality is presented, in terms of cluster signal-difference-to-noise ratio (SDNR) intercomparison among digital breast tomosynthesis (DBT) and 2-dimensional (2D) and synthetic-2-dimensional (s2D) mammography. A phantom that provides realistic appearance of MC clusters located in uniform and nonuniform background was imaged in 2D and DBT, considering various scattering conditions. MC cluster SDNR differentiation is investigated with respect to MC particle size (uniform background) and surrounding parenchyma density (nonuniform background). An accurate MC cluster segmentation method was used to delineate individual MC particles and estimate MC cluster SDNR. Analysis of the uniform part of the phantom indicated higher performance of DBT and 2D over s2D for the smallest cluster size (106-177 µm), no difference among mammographic modes for the largest MC cluster (224-354 µm), and enhanced role of 2D for decreasing cluster size and increasing scattering. Analysis of the nonuniform part of the phantom indicated DBT performed better than 2D and s2D in case of dense parenchyma pattern, while 2D and s2D did not differ across parenchyma density patterns and scattering conditions. The presented MC cluster SDNR analysis was capable of revealing subtle differences among mammographic modes and suggests a methodology for clinical image quality assessment. Graphical abstract.

PATIENT DOSE DURING THERAPEUTIC ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY PROCEDURE.

Endoscopic retrograde cholangiopancreatography (ERCP) is a standard technique for the diagnosis and treatment of disorders of the pancreas or bile ducts. The aim of this study was the measurement of the radiation dose to patients during therapeutic ERCP procedures, in order to estimate the patient effective dose (ED). Fifteen patients were studied using a fluoroscopy system equipped with automatic brightness control and pulse fluoroscopy mode. Fluoroscopy time (FT), cumulative dose (Ka,r) and air kerma-area product (PKA) were collected for ERCP procedures. The ED was calculated from PKA values. The FT was ranged from 0.68 to 5.57 min, with the mean value of 2.50 min; the Ka,r was ranged from 2.22 to 19.10 mGy, with the mean value of 7.71 mGy; and the PKA was ranged between 0.59 and 5.10 Gycm2, with the mean value of 2.03 Gycm2. The ED ranged from 0.11 to 0.97 mSv, whilst the mean and median ED values were 0.39 and 0.32 mSv, respectively. FT and radiation dose to the patients were either comparative or significantly lower than those previously reported.

OPTIMISATION OF PATIENT DOSE AND IMAGE QUALITY IN ENDOSCOPIC RETROGRADE CHOLANGIOPANCREATOGRAPHY: A PHANTOM-BASED EVALUATION.

A phantom-based study is presented aiming to optimise patient dose and image quality (IQ) in endoscopic retrograde cholangiopancreatography procedures, utilising a fluoroscopy system equipped with a flat panel detector. The patient thickness was simulated with various polymethyl methacrylate slabs, whilst IQ was evaluated using the Leeds test object. The main factors evaluated were phantom thickness, distance between phantom and detector, field of view and pulse rate. For all these factors, the dosemetric indices, entrance surface air kerma (ESAK) rate and ESAK per pulse, as well as the IQ parameters, signal-to-noise ratio and high contrast spatial resolution, were measured. Based on these measurements, the figure of merit (FOM) was estimated. The FOM and ESAK rate values indicated the optimum combination of the factors evaluated which could provide adequate clinical information, assuring minimum patient dose.

Patient Radiation Doses in Therapeutic Endoscopic Retrograde Cholangiopancreatography in Patras and the Key Role of the Operator.

The patient radiation doses, in conjunction with the operator experience, in therapeutic endoscopic retrograde cholangiopancreatography (ERCP) procedures, performed in our hospital, were obtained. Ninety-six patients participated in the study and were divided into 3 groups, based on the operator experience. The dosemetric indices, fluoroscopy time (FT), cumulative dose (Ka,r) and air kerma-area product (PKA), were collected. For the total and weight banding group the third quartile values of the distribution of FT, Ka,r and PKA were 2.90 and 2.92 min, 6.89 and 6.93 mGy and 1.84 and 1.85 Gycm2, respectively, and were comparative or significantly lower than the corresponding values previously reported. Taking as a criterion the operator, the differences in the patient radiation doses were statistically significant, with the highest dose recorded for the operator of the lowest experience degree. The values obtained could contribute in establishing local and national diagnostic reference levels and in optimising ERCP procedure.

The effect of increased body mass index on patient dose in paediatric radiography.

Radiation protection is of particular importance in paediatric radiology. In this study, the influence of increased body mass index (BMI) in radiation dose and associated risk was investigated for paediatric patients aged 5-6.5 years, undergoing chest (64 patients) or abdomen (64 patients) radiography. Patients were categorized into normal and overweight, according to the BMI classification scheme. Entrance surface dose (ESD), organ dose, effective dose (ED) and risk of exposure induced cancer death (REID) were calculated using the Monte Carlo based code PCXMC 2.0. Statistically significant increase in patient radiation dose and REID was obtained for overweight patients as compared to normal ones, in both chest and abdomen examinations (Wilcoxon singed-rank test for paired data, p<0.001). The percentage increase in overweight as compared to normal patients of ESD, organ dose (maximum value), ED and REID was 13.6%, 24.4%, 18.9% and 20.6%, respectively, in case of chest radiographs. Corresponding values in case of abdomen radiographs were 15.0%, 24.7%, 21.8% and 19.8%, respectively. An increased BMI results in increased patient radiation dose in chest and abdomen paediatric radiography.