Search

This study aimed to evaluate the impact of three two-dimensional (2D) mammographic acquisition techniques on image quality and radiation dose in the presence of silicone breast implants (BIs). Then, we propose and validate a new International Atomic Energy Agency (IAEA) phantom to reproduce these techniques. Images were acquired on a single Hologic Selenia Dimensions® unit. The mammography of the left breast of a single clinical case was included. Three methods of image acquisition were identified. They were based on misused, recommended, and reference settings. In the clinical case, image criteria scoring and the signal-to-noise ratio on breast tissue (SNRBT) were determined for two 2D projections and compared between the three techniques. The phantom study first compared the reference and misused settings by varying the AEC sensor position and, second, the recommended settings with a reduced current-time product (mAs) setting that was 13% lower. The signal-difference-to-noise ratio (SDNR) and detectability indexes at 0.1 mm (d' 0.1 mm) and 0.25 mm (d' 0.25 mm) were automatically quantified using ATIA software. Average glandular dose (AGD) values were collected for each acquisition. A statistical analysis was performed using Kruskal–Wallis and corrected Dunn tests (p < 0.05). The SNRBT was 2.6 times lower and the AGD was −18% lower with the reference settings compared to the recommended settings. The SNRBT values increased by +98% with the misused compared to the recommended settings. The AGD increased by +79% with the misused settings versus the recommended settings. The median values of the reference settings were 5.8 (IQR 5.7–5.9), 1.2 (IQR 0.0), 7.0 (IQR 6.8–7.2) and 1.2 (IQR 0.0) mGy and were significantly lower than those of the misused settings (p < 0.03): 7.9 (IQR 6.1–9.7), 1.6 (IQR 1.3–1.9), 9.2 (IQR 7.5–10.9) and 2.2 (IQR 1.4–3.0) mGy for the SDNR, d' 0.1 mm, d' 0.25 mm and the AGD, respectively. A comparison of the recommended and reduced settings showed a reduction of −6.1 ± 0.6% (p = 0.83), −7.7 ± 0.0% (p = 0.18), −6.4 ± 0.6% (p = 0.19) and −13.3 ± 1.1% (p = 0.53) for the SDNR, d' 0.1 mm, d' 0.25 mm and the AGD, respectively. This study showed that the IAEA phantom could be used to reproduce the three techniques for acquiring 2D mammography images in the presence of breast implants for raising awareness and for educational purposes. It could also be used to evaluate and optimize the manufacturer's recommended settings. [ABSTRACT FROM AUTHOR]

Background/Objectives: To define and evaluate a radiation dose optimization process for chest computed tomography (CT) imaging. Methods: Data from unenhanced and enhanced chest CT acquisitions performed between June 2018 and January 2020 in adult patients were included in the study. Images were acquired on a Siemens SOMATOM® Definition Edge CT. Dose values, including Dose.Length Product (DLP) and Volume CT Dose Index (CTDIvol), were collected. Low doses (LDs, 25th percentiles), achievable doses (ADs, 50th percentiles), and diagnostic reference levels (DRLs, 75th percentiles) were calculated before and after parameter modifications. A process was defined and applied to patient data. For unenhanced chest CT, data were differentiated according to three groups: high dose (HD), optimized dose (OD), and ultra-low dose (ULD). Dosimetric changes between protocols were expressed as mean CTDIvol % (CI95%). A Mann and Whitney statistical test was used. The diagnostic quality score (DQS) of a subset of 70 randomly selected CT examinations was evaluated by one radiologist. The DQS was scored according to a three-point Likert scale: (1) poor (definite diagnosis impossible), (2) fair (evaluation of major findings possible), and (3) excellent (exact diagnosis possible). Results: Data were collected from 1929 patients. For unenhanced chest CT protocols, only one process loop was run. A dose comparison between the chest CT protocol before the use of the process and the three groups showed a decrease of −38.3% (9.7%) and −93.4% (24.2%) for OD and ULD, respectively, and an increase of +29.4% (4.7%) for HD. For the enhanced chest CT protocol, two optimization loops were performed, and they resulted in a mean dose reduction of −50.0% (2.6%) compared to the pre-optimization protocol. For all protocols, the DQS was greater than or equal to 2. Conclusions: We proposed a radiation dose optimization process for chest CT that could significantly reduce the dose without compromising diagnosis. [ABSTRACT FROM AUTHOR]

Background/Objectives: Radiography is an essential and low-cost diagnostic method in pulmonary medicine that is used for the early detection and monitoring of lung diseases. An adequate and consistent image quality (IQ) is crucial to ensure accurate diagnosis and effective patient management. This pilot study evaluates the feasibility and effectiveness of the International Atomic Energy Agency (IAEA)'s remote and automated quality control (QC) methodology, which has been tested in multiple imaging centers. Methods: The data, collected between April and December 2022, included 47 longitudinal data sets from 22 digital radiographic units. Participants submitted metadata on the radiography setup, exposure parameters, and imaging modes. The database comprised 968 exposures, each representing multiple image quality parameters and metadata of image acquisition parameters. Python scripts were developed to collate, analyze, and visualize image quality data. Results: The pilot survey identified several critical issues affecting the future implementation of the IAEA method, as follows: (1) difficulty in accessing raw images due to manufacturer restrictions, (2) variability in IQ parameters even among identical X-ray systems and image acquisitions, (3) inconsistencies in phantom construction affecting IQ values, (4) vendor-dependent DICOM tag reporting, and (5) large variability in SNR values compared to other IQ metrics, making SNR less reliable for image quality assessment. Conclusions: Cross-comparisons among radiography systems must be taken with cautious because of the dependence on phantom construction and acquisition mode variations. Awareness of these factors will generate reliable and standardized quality control programs, which are crucial for accurate and fair evaluations, especially in high-frequency chest imaging. [ABSTRACT FROM AUTHOR]

Abstract Purpose To determine the variation in target delineation of nasopharyngeal carcinoma and the impact of measures to minimize this variation. Materials and methods For ten nasopharyngeal cancer patients, ten observers each delineated the Clinical Target Volume (CTV) and the CTV elective. After 3D analysis of the delineated volumes, a second delineation was performed. This implied improved delineation instructions, a combined delineation on CT and co-registered MRI, forced use of sagittal reconstructions, and an on-line anatomical atlas. Results Both for the CTV and the CTV elective delineations, the 3D SD decreased from Phase 1 to Phase 2, from 4.4 to 3.3 mm for the CTV and from 5.9 to 4.9 mm for the elective. There was an increase agreement, where the observers intended to delineate the same structure, from 36 to 64 surface % (p = 0.003) for the CTV and from 17 to 59% (p = 0.004) for the elective. The largest variations were at the caudal border of the delineations but these were smaller when an observer utilized the sagittal window. Hence, the use of sagittal side windows was enforced in the second phase and resulted in a decreased standard deviation for this area from 7.7 to 3.3 mm (p = 0.001) for the CTV and 7.9 to 5.6 mm (p = 0.03) for the CTV elective. Discussion Attempts to decrease the variation need to be tailored to the specific causes of the variation. Use of delineation instructions multimodality imaging, the use of sagittal windows and an on-line atlas result in a higher agreement on the intended target.

An efficient nano-sized delivery system is presented here allowing the immobilized, picolinium-tethered organic ligand to be released by X-ray irradiation. A marked difference was observed in the fragmentation efficiency by using conventional Cs-137 vs. pulsed sources., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Objective: Little is known about the effectiveness of dose reduction options according to breast thickness. The purpose of this phantom study was to compare the effects on dose and noise of bismuth shielding versus a low kilovoltage for different breast thicknesses., Materials and Methods: CT acquisitions were performed first at 120 kVp (reference acquisition), then at 120 kVp with shielding and at 100 kVp without shielding on a phantom with three different prosthetic breast thicknesses, corresponding to the minimum, median, and maximum values first measured in a sample of 30 female thoracic CT examinations, which were randomly selected. Breast doses were measured with optically stimulated luminescence dosimeters placed on and beneath the prosthetic breast. For noise evaluation, the CT number SDs were measured within six ROIs at increasing depths., Results: Taking into account all breast thicknesses, the average breast dose was reduced by 42.1% with shielding and by 33.0% at 100 kVp (p=0.009). In-depth noise increased less with shielding (19.0% vs 32.1%, p<0.0001). For 1-cm breast thickness, the breast dose fell by 46.5% and 29.7% with shielding and 100 kVp, respectively (p=0.01), and in-depth noise increased by 19.5% and 33.9% (p=0.01). The corresponding values for 2-cm breast thickness were -38.5% and -30.1%, (p=0.02) and 16.5% and 33.5% (p=0.001), whereas those for 4-cm thickness were -40.6% and -40.5% (p=0.95) and 20.7 and 29.2% (p=0.02)., Conclusion: Greater breast dose reduction is achieved by shielding for breast thicknesses less than 4 cm. Regardless of breast thickness, shielding leads to a smaller increase in in-depth noise.