AEC Mode Research Articles

Performance of dual-energy subtraction in contrast-enhanced mammography for three different manufacturers: a phantom study

BackgroundDual-energy subtraction (DES) imaging is critical in contrast-enhanced mammography (CEM), as the recombination of low-energy (LE) and high-energy (HE) images produces contrast enhancement while reducing anatomical noise. The study's purpose was to compare the performance of the DES algorithm among three different CEM systems using a commercial phantom.MethodsA CIRS Model 022 phantom, designed for CEM, was acquired using all available automatic exposure modes (AECs) with three CEM systems from three different manufacturers (CEM1, CEM2, and CEM3). Three studies were acquired for each system/AEC mode to measure both radiation dose and image quality metrics, including estimation of measurement error. The mean glandular dose (MGD) calculated over the three acquisitions was used as the dosimetry index, while contrast-to-noise ratio (CNR) was obtained from LE and HE images and DES images and used as an image quality metric.ResultsOn average, the CNR of LE images of CEM1 was 2.3 times higher than that of CEM2 and 2.7 times higher than that of CEM3. For HE images, the CNR of CEM1 was 2.7 and 3.5 times higher than that of CEM2 and CEM3, respectively. The CNR remained predominantly higher for CEM1 even when measured from DES images, followed by CEM2 and then CEM3. CEM1 delivered the lowest MGD (2.34 ± 0.03 mGy), followed by CEM3 (2.53 ± 0.02 mGy) in default AEC mode, and CEM2 (3.50 ± 0.05 mGy). The doses of CEM2 and CEM3 increased by 49.6% and 8.0% compared with CEM1, respectively.ConclusionOne system outperformed others in DES algorithms, providing higher CNR at lower doses.Relevance statementThis phantom study highlighted the variability in performance among the DES algorithms used by different CEM systems, showing that these differences can be translated in terms of variations in contrast enhancement and radiation dose.Key PointsDES images, obtained by recombining LE and HE images, have a major role in CEM.Differences in radiation dose among CEM systems were between 8.0% and 49.6%.One DES algorithm achieved superior technical performance, providing higher CNR values at a lower radiation dose.Graphical

Effects of Dose and Image Quality according to Center Location in Lumbar Spine Lateral Radiography Using AEC Mode

Effects of Dose and Image Quality according to Center Location in Lumbar Spine Lateral Radiography Using AEC Mode

Silica modification with 9-methylacridine and 9-undecylacridine as mixed-mode stationary phases in HPLC

In this research, 9-methylacridine and 9-undecylacridine were synthesized through Bernthsen's reaction and well characterized using gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). Two mixed-mode stationary phases were developed by functionalizing silica with 9-methylacridine and 9-undecylacridine. Then, two modified silicas were characterized by elemental analysis, thermogravimetric analysis (TGA), and fourier transform-infrared spectroscopy (FT-IR). Due to the extent of conjugative rings, the hydrophobic hydrocarbon chain, and anion exchange sites of 9-methylacridinium and 9-undecylacridinium group on the silica gel of columns, mixed-mode stationary phases were designed with multiple interactions including π-π stacking interaction, reverse phase, hydrophilic interaction, and anion exchange. According to the type of acridine, different interactions may be formed in the target column. Polycyclic aromatic hydrocarbons (PAHs), alkylbenzenes, pyridines and parabens were chromatographed on π-π stacking modes and RPLC, where anion exchange sites can be applied for the separation of inorganic anions on AEC mode. Considering the structure of the stationary phases, these columns were used to separate organic compounds with higher polarity on the HILIC retention. The performance of the columns was investigated by the chromatographic parameters in terms of column efficiency (N/m), asymmetry factor (Af), retention factor (k), and resolution (Rs). The mixed-mode stationary phases can be successfully employed to conduct chromatographic separation on a wide range of samples with a single column.

274. Multi hospital experiences of Radiation Dose Index Monitoring (RDMI) in mammography

Purpose Aim of this work was to use the dose index information from 5 mammography units within USL Toscana Centro, Firenze-Empoli area, analysing and comparing the compression force data and the AGD trend with the thickness of the compressed breast. Methods The RDMI data from Siemens Mammomat Inspiration mammography units were analysed by exploiting the information gathered in a local LOG file that records all the exposure parameters of each single shot. Data in the file are extracted in a spreadsheet tool. All the devices have the same kV-breast thickness compensation curve and work in AEC mode with a W/Rh combination. For the analysis, we focused on data for the year 2015–2016 covering about 40,000 patients for a total of over 169,200 projections. Data are filtered eliminating quality test and manual exposures, breast implants and surgical pieces. Results The average compression force values, for the year 2015, are similar in the first 4 unit. For the Unit 5, it’s found that the breast is significantly less compressed. After a training session on the correct use of the compression paddle, data for year 2016 were analysed. Since then, there are comparable forces with other devices. Nevertheless, for all mammography, there is a very large compression range, with maximum points greater than 200 N and values at the lower limit of 20 N. For the analysis of AGD vs thickness, all devices fall within the EUREF limit values (see Table). Conclusions Data collection has allowed to investigate and compare retrospectively all exams executed in the year 2015 −2016, evaluate anomalies not highlighted with quality assurance tests and take corrective actions to improve performance. Download : Download high-res image (128KB) Download : Download full-size image

DBT Image quality investigation: A phantom study

Introduction Digital breast tomosynthesis (DBT) is a widely used imaging modality employing a limited number of projections to reconstruct the breast volume. Despite its large use in clinical practice, an objective evaluation of DBT reconstructed imagesis a hard task since the majority of the systems produces and exports images strongly affected by the post processing algorithm. Moreover only few phantoms are available for this need. Purpose The aim of this study is to investigate how, a newly developed phantom (Tomophan®), can be used to assess image quality of unprocessed images exported by Fujifilm® system. Materials and methods The system studied allows exporting raw reconstructions. Moreover, it offers two acquisition modalities: standard and high resolution (ST/HR-mode). The phantom was exposed in AEC mode with both modalities. Tomophan® allows different IQ analysis to be performed. We chose to investigate in plane and cross plane spatial resolution by adapting standard metrics: MTF and PSF. For these two parameters, significant differences were expected. Moreover a CNR measure was done. Results Results obtained using the TomophanQA®software confirm that acquisition in HR-mode produces better results in terms of in plane resolution [MTF 0.5 (HR/ST) = 2.7/1.8 mm −1 (x-direction) MTF 0.5 (HR/ST) = 1.6/1.3 mm −1 (y-direction)] and cross plane z-resolution [FWHM(HR/ST) = 1.6/4.3 mm]. CNR evaluation demonstrates that in HR-mode a doubled entrance dose is needed to get the same CNR value as ST-mode. Conclusion Objective image quality assessment in DBT could be easly assessed with the Tomophan® phantom. Caution is recommended when performing this analysis on processed image due to non linear signal transformation of post processing. Disclosure Nothing to disclose.

Comparison of Exposure Dose by Using AEC Mode of Abdomen AP Study in Radiography

Comparison of Exposure Dose by Using AEC Mode of Abdomen AP Study in Radiography

디지털 흉부엑스선 검사에서 환자선량 감소를 위한 부가필터와 Ion chamber 센서 조합

In this paper, we studied additional filter and Ion chamber combinations to reduce patient dose without decreasing image quality in digital chest x-ray projection. The experiment set 125 kVp, 320 mA, AEC mode. Ion chamber sensors was divided by 4 cases of combinations, then, we measured patient dose and calculated organ dose using PCXMC. Also, physical image assessment using MTF was performed. As a results, The surface entrance dose and organ dose were the lowest when selecting both left and right Ion chamber sensors under the same conditions of additional filter. In image quality assessment, The spatial frequency scored 2.494 lp/mm which was highest when selecting both right and left Ion-chambers and 0.1 mmCu filter. And to conclude, to select both right and left Ion chamber sensors and 0.1 mmCu filter will help for acquiring good quality image as well as reducing patient dose.

Experimental evaluation of the image quality and dose in digital mammography: Influence of x-ray spectrum

In this work, we studied experimentally the influence of x-ray spectrum on the contrast-to-noise ratio (CNR) and the average glandular dose (MDG) for two digital mammography systems: Senographe 2000D (GE Medical Systems) and Lorad Selenia (Hologic), with indirect and direct detector imaging technology, respectively. CNR and MGD were determined using PMMA phantoms simulating breasts with thicknesses of 4 cm and 6 cm. All available anode/filter combinations of the systems were evaluated for a wide range of tube voltages values. Results indicated that the Rh/Rh combination provides the highest image quality with the lower mean glandular dose for the Senographe 2000D system. For the Lorad Selenia system, the W/Ag combination at 30 kV showed the best performance, in terms of dose saving and image quality improvement in relation to all tube voltage range. The comparison between the optimal x-ray spectra and those selected by the AEC mode showed that this automatic selection mechanism could be readjusted to optimize the relationship between image quality and dose.

Image quality and dose analysis for a PA chest X-ray: Comparison between AEC mode acquisition and manual mode using the 10 kVp ‘rule’

PurposeTo compare the image quality and effective dose applying the 10 kVp rule with manual mode acquisition and AEC mode in PA chest X-ray. Method68 images (with and without lesions) were acquired using an anthropomorphic chest phantom using a Wolverson Arcoma X-ray unit. These images were compared against a reference image using the 2 alternative forced choice (2AFC) method. The effective dose (E) was calculated using PCXMC software using the exposure parameters and the DAP. The exposure index (lgM provided by Agfa systems) was recorded. ResultsExposure time decreases more when applying the 10 kVp rule with manual mode (50%–28%) when compared with automatic mode (36%–23%). Statistical differences for E between several ionization chambers' combinations for AEC mode were found (p = 0.002). E is lower when using only the right AEC ionization chamber. Considering the image quality there are no statistical differences (p = 0.348) between the different ionization chambers' combinations for AEC mode for images with no lesions. Considering lgM values, it was demonstrated that they were higher when the AEC mode was used compared to the manual mode. It was also observed that lgM values obtained with AEC mode increased as kVp value went up. The image quality scores did not demonstrate statistical significant differences (p = 0.343) for the images with lesions comparing manual with AEC mode. ConclusionIn general the E is lower when manual mode is used. By using the right AEC ionising chamber under the lung the E will be the lowest in comparison to other ionising chambers. The use of the 10 kVp rule did not affect the visibility of the lesions or image quality.

디지털 흉부영상에서 자동노출제어 및 감도변화를 이용한 영상품질의 정량적인 평가

자동노출제어장치를 사용하는 흉부 후전 검사는 이온전리조의 선택에 따라 환자가 받는 피폭선량이 달라진다. 본 논문에서는 자동노출제어장치의 이온전리조의 선택에 따른 최적의 진단 영상을 획득하면서 피폭선량을 최소화하는 방안에 대해 연구하였다. 실험방법은 흉부 후전 검사와 동일한 조건으로 자동노출제어장치의 이온전리조 선택과 감도변화에 따라 실험하였다. 이온전리조의 상단 2개, 하단 1개의 센서를 on/off 선택에 따라 7가지의 경우로 나누어 각각 5회씩 측정하여 평균값을 구하고 피폭선량을 산출하였다. 영상평가는 변조전달함수, 최대신호 대 잡음비, 평균제곱근, 신호 대 잡음비, 대조도 대 잡음비, 평균대표준편차비를 각각 측정하여 평가를 시행하였다. 실험결과 피폭선량 평가에서 이온전리조 상단 2개를 선택한 경우가 다른 조합에 비해 가장 낮은 선량을 나타내었고, 해상력 평가결과로는 감도 625(High)에서 상단2개를 선택한 영상이 두 번째로 높은 공간주파수 1.343 lp/mm를 나타내었다. 상단 2개를 선택한 영상의 평균제곱근 결과값이 두 번째로 낮게 나타났으며, 신호 대 잡음비, 대조도 대 잡음비, 평균 대 표준편차비는 두 번째로 높은 결과값을 나타내었다. 그리고 감도가 증가함에 따라 피폭선량은 감소하였으며, 영상품질 측면에서도 보다 우수한 영상을 얻을 수 있었다. 따라서 피폭선량을 최소화하고, 최적의 의료 영상을 얻기 위해서는 감도 625(High)에서 이온전리조 상단 2개를 선택하는 것이 임상적으로 유용할 것으로 사료된다. The patient radiation dose is different depending on selection of Ion chamber when taking Chest PA which using AEC. In this paper, we studied acquiring the best diagnostic images according to selection of Ion chamber on AEC mode as well as minimizing patient radiation dose. Experimental methods were selection of Ion chamber and change of sensitivity under the same conditions as Chest PA projection. At AEC mode, two upper ion chambers sensors and one lower ion chamber sensor were divided into 7 cases according to selection of on/off. after measuring five times respectively, we obtained average value and calculated exposure dose. Image assessment was done with measured Modulation Transfer Function, Peak Signal to Noise Ratio, Root Mean Square, Signal to Noise Ratio, Contrast to Noise Ratio, Mean to Standard deviation Ratio respectively. In exposure assessment results, selection of two upper chambers was the lowest. In resolution assessment results, image of two upper chambers had the second high spatial frequency at sensitivity at 625(High) was 1.343 lp/mm. RMS value of image selecting two upper chambers was low secondly. SNR, CNR, MSR were the high value secondly. As the sensitivity was increased, radiation dose was decreased but better image could be obtained on image quality. In order to obtain the best medical images while minimizing the dose, usage of two upper ion chambers is considered to be clinically useful at sensitivity 625(High).

SU-E-I-110: Minimized Pediatric Dose in Direct Radiography (DR).

Pediatric x-rays techniques are not standardized. They depend upon: patient size, anatomical localized and equipment manufacturers. Most pediatric techniques use the default factory settings. This project's goal is to find the best compromise between dose to pediatric patients and optimal image quality. Low contrast discrimination is the key to image quality. The manufacturers (Philips and GE) specific techniques were used to establish baseline values. The following factors were evaluated: kVp, mA, time, use of grid, collimation, focal spot size, AEC/manual, and added filters. The entrance skin exposure, entrance exposure to detector, equipment exposure index (EI) and contrast to noise ratio (CNR) for different thickness from neonatal to average child were assessed. Overall, some manufacturer's specific pediatric exposures techniques have higher entrance skin exposure than typical specified techniques. Equipment reported exposure index are not accurate enough to be used as 'dosimeter'. Lower kVp, mA with longer exposure time will increase the low contrast detectability with better CNR but these also change the entrance skin exposure. Removal of grid, filters do reduce the entrance skin exposure, but these also reduce low contrast detectability. Focal spot size does not make a big impact in image quality due to the average detector pixel size. Collimation does make a difference in AEC sensitivity and exposure index (EI). There is no single technique that is the best technique. It is all depend upon many factors like exam type and the size of the patients. Moreover, it is difficult to program the generator to use low kVp techniques, add or remove of filters, collimation, and use of AEC or manual mode, grid on or off in order to optimize the image quality while minimizing the dose to the patients. Some pediatric techniques with their associate CNR and radiation dose will be presented.

MO‐FF‐A4‐02: Effects of Added X‐Ray Beam Cu Filtration On Image Quality and Patient Dose in Digital Radiography

Purpose: To quantify effects of added x‐ray beam Cu filtration on image quality, skin entrance exposure, and effective dose in digital radiography. Method and Materials: A GE Definium 8000 DR unit, in AEC mode, was used with a 20 cm thick acrylic phantom to simulate an average adult abdomen. 0.0, 0.1, and 0.2‐mm of Cu filtration were added to the x‐ray beam. We used 75, 80, 85, 90, 95, 100, and 110kV. Image quality was compared using a contrast‐detail phantom (CDRAD). For each beam quality, we exposed the CDRAD phantom on top, below, and between two 10‐cm sections of the acrylic phantom, and at four different orientations relative to anode‐cathode axis. The results were averaged. Image processing parameters were the ones used clinically for an AP Abdomen exam. The images were analyzed using the CDRAD Analyzer software. Skin‐entrance exposures, based on AEC resultant mAs read‐out, were measured without backscatter, and effective doses for an average size adult phantom were calculated using the PCXMC software. Results: At 75–80kV addition of Cu filtration reduced image quality slightly (∼1–5%), skin‐entrance exposure by 38–52%, and effective dose by 12–21% relative to no additional Cu filtration. At 90–110kV image quality varied little (∼0–4%) with added Cu filtration, skin entrance exposure was reduced by 28–47%, and effective dose was reduced by up to 17%. Only at 85 kV image quality was reduced significantly (∼13–15%) with added Cu filtration. Skin‐entrance exposure was reduced by 35–48%, and effective dose was reduced by 8–17%. Conclusion: Although already a relatively low dose modality, DR may benefit from the use of additional x‐ray beam Cu filtration since, for most x‐ray beam qualities, image quality appears to change little, while patient doses are reduced more appreciably compared to using beams with no additional Cu filtration.