The purpose of this study was to investigate physical characteristics of two full field digital mammography (FFDM) systems (GE Senographe Essential and DS). Both are indirect conversion (x ray to light) alpha-Si flat panels coupled with a CsI(Tl) scintillator. The examined systems have the same pixel size (100 microm) but a different field of view: a conventional size 23 x 19.2 cm2 and a large field 24 X 30.7 cm2, specifically designed to image large breasts. In the GE Senographe Essential model relevant improvements in flat panel design were implemented and new deposition tools for metal, alpha-Si, and CsI(Tl) were introduced by GE. These changes in detector design are expected to be beneficial for advanced applications such as breast tomosynthesis. The presampling modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were measured for a wide range of exposure (25-240 microGy) with a RQA-M2 technique (28 kVp with a Mo/Mo target/filter combination and 2 mm of additional aluminum filtration). At 1, 2, and at 4 lp/mm MTF is equal to 0.9, 0.76, and 0.46 for the conventional field detector and to 0.85, 0.59, and 0.24 for the large field detector. The latter detector exhibits an improved NNPS due to a lower electronic noise and a better DQE that reaches 60%. In addition a contrast-detail analysis was performed with CDMAM 3.4 phantom and CDCOM software: GE Senographe DS showed statistically significant poorer detection ability in comparison with the GE Senographe Essential. These results could have been expected, at least qualitatively, considering the relative DQE of the two systems.
Recently a new iterative reconstruction algorithm named Sinogram Affirmed Iterative Reconstruction (SAFIRE) has been released by Siemens. This algorithm works in the raw data domain with noise reduction as main purpose, providing five different strengths. In this study, the effect of SAFIRE on image quality has been investigated using selected phantoms and a comparison with standard filtered back projection (FBP) has been carried out. The following quantitative parameters have been evaluated: image noise, impact of different reconstruction kernels on noise reduction, noise power spectrum (NPS), contrast‐to‐noise ratio (CNR), spatial resolution, and linearity and accuracy of CT numbers. The influence of strengths on image quality parameters has also been examined. Results show that image noise reduction is independent of reconstruction kernel and strongly related to the strength of SAFIRE applied. The peak of NPS curve for SAFIRE reconstructions is shifted towards low frequencies; this effect is more marked at higher levels of strength. Contrast‐to‐noise ratio is always improved in SAFIRE reconstruction and increases with higher strength. At different dose levels SAFIRE preserves CT number accuracy, linearity, and spatial resolution, both in transversal and coronal planes. These results confirm that SAFIRE allows for image noise reduction with preserved image quality. First clinical data to validate this phantom analysis and confirm that commercially available iterative algorithms can play an effective role in dose containment.PACS number: 87.57.Q
Background: Prostate-specific membrane antigen
(PSMA) has gained high attention as a useful biomarker in the imaging
evaluation of prostate cancer with positron emission tomography (PET)
during recent years. [68Ga]-labeled Glu-urea-Lys(Ahx)-HBED-CC
([68Ga]-PSMA-HBED-CC) is a novel PSMA inhibitor radiotracer
which has demonstrated its suitability in detecting prostate cancer.
Preparation conditions may influence the quality and in vivo behavior
of this tracer, and no standard procedure for the quality control
(QC) is available. The aim of this study was to develop a new rapid
and simple high-pressure liquid chromatography method of analysis
for the routine QCs of [68Ga]-PSMA-HBED-CC to guarantee
the high quality of the radiopharmaceutical product before release. Methods: A stepwise approach was used based on the quality
by design concept of the International Conference of Harmonisation
Q2 (R1) and Q8 (Pharmaceutical Development) guidelines in accordance
with the regulations and requirements of European Association of Nuclear
Medicine, Society of Nuclear Medicine, International Atomic Energy
Agency, World Health Organization, and Italian Association of Nuclear
Medicine and Molecular Imaging. The developed analytical test method
was validated because a specific monograph in the pharmacopoeia is
not available for [68Ga]-PSMA-HBED-CC. Results: The purity and quality of the radiopharmaceutical obtained according
to the proposed method resulted high enough to safely administrate
it to patients. An excellent linearity was found between 0.8 and 5
μg/mL, with a detection limit of 0.2 μg/mL. Assay imprecision
(% CV) was <2%. Conclusions: The developed method
to assess the radiochemical and chemical purity of [68Ga]-PSMA-HBED-CC
is rapid, accurate, and reproducible, allowing routinely the use of
this PET tracer as a diagnostic tool for imaging prostate cancer and
also assuring patient safety.
Highlights
A large number of high resolutions thorax CT scans collected for suspected SARS-CoV-2 infection.
The use of an advanced software guarantees a great accuracy to calculate organ doses and effective doses.
Monitoring in real time all the dosimetric aspects of COVID-19 outbreak;
Cancer risk estimation according to the BEIR VII.
Dose optimization in radiological examinations is a mandatory issue: in this study local Diagnostic Reference Levels (lDRLs) for Clinical Mammography (MG), Computed Tomography (CT) and Interventional Cardiac Procedures (ICP) performed in our Radiology Department were established. Using a dose tracking software, we have collected Average Glandular Dose (AGD) for two clinical mammographic units; CTDIvol, Size-Specific Dose Estimate (SSDE), Dose Length Product (DLP) and total DLP (DLPtot) for five CT scanners; Fluoro Time, Fluoro Dose Area Product (DAP) and total DAP (DAPtot) for two angiographic systems. Data have been compared with Italian Regulation and with the recent literature. The 75th percentiles of the different dosimetric indices have been calculated. Automated methods of radiation dose data collection allow a fast and detailed analysis of a great amount of data and an easy determination of lDRLs for different radiological procedures.
The aim of the study is to use the well-known channelized Hotelling observer model (CHO) to characterize a recently installed angiography system (GE Discovery IGS 740) using sets of images of a contrast-detail phantom acquired with clinical protocols. A Leeds TO10 phantom was used. The phantom has 108 details: 12 diameters (size range: 0.25 mm–11 mm), each with nine contrasts (declared range: 0.012–0.930 at 70 kVp 1.00 with 1 mm Cu filtration). TO10 has been imaged between two 10 cm thick homogeneous solid water slabs. Two FOVs (32 cm and 20 cm) were used. Fluoroscopy images were taken using an abdominal protocol at two different frame rates (15 fps and 7.5 fps) and at two dose levels (low and normal); cineangiography images were acquired using an abdominal protocol at 15 fps at two dose levels (low and normal). A 40 Gabor channels CHO with internal noise was used. Human observers’ studies were carried out to tune the internal noise parameter and to validate the model observer. Contrast-detail curves were obtained from the CHO output using a visibility threshold of 75% and fitted with Rose’s model theory in order to characterize the angiography system. Wilcoxon rank-sum tests were performed to investigate possible differences among the different sets of images.
The CHO can distinguish between the two dose levels (p -values < 0.002), while FOV and frame rate do not affect the contrast-detail curves significantly. It is important to note that the CHO does not find statistically significant differences between a fluoroscopy with FOV = 20 cm at normal dose level (17.6 mGy min−1) and a cineangiography with FOV = 32 cm low dose level (42.1 mGy min−1). This result can lead to a dose reduction of about 70% for our specific task (i.e. a static, disc shaped object at known location in homogeneous field). Given their stability in comparison to human observers, model observers provide an effective tool for image quality evaluation.
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