AEC System Research Articles

Asset Based Community Development as a Method to Strengthen ASEAN Economic Community

Indonesia as ASEAN member already binds to ASEAN Economic Community as consequences of Indonesia membership. It means, Indonesia have to apply the liberalization in goods trade whether for import goods or for export goods. As a goal and based on the goal set up by ASEAN Economic Community, the single market should be the way to prosperous people economic. The question is how to achieve this goal instead of pushing or destroying local goods from export goods. It needs to straight up the vision, back to previous goal, and take action to strengthen power or advantages from goods and from AEC system. One of the ways to achieve it is with Asset Based Community Development. This paper will analyze Asset Based Community Development as a means to strengthen ASEAN Economic Community. In Part I, this paper will examine the concept of ASEAN Economic Community. Part II will analyze further on what are the steps of Asset Based Community Development required in intensifying ASEAN Economic Community, and Part III is conclusion.

Application of DQE for quantitative assessment of detectors to estimate AEC efficiency in digital mammography

Abstract Optimisation of the detector’s exposure parameters settings for image quality and patient dose is an important task in digital mammography. Assessment of a digital detector’s performance can be done objectively and without operator bias by determining the Detective Quantum Efficiency (DQE). The authors of this article aim to prove that the performance of the AEC system can be objectively portrayed through DQE. The results were examined for influence of KAD changes on DQE values and to determine if it was possible to obtain similar DQE values for different exposures. While analysing the effect of the operation of the AEC system described with DQE, the doses received by women during mammography examinations were considered, as well. The AEC system’s exposure control mechanism cannot guarantee the same DQE value for different object thicknesses. When the object thickness increases, the AEC system should increase the KAD value to obtain the same DQE value. The result of increasing KAD would be the increase of mean glandular dose for some women. However, assuming that DQE is a good indicator of image quality, introducing the proposed changes to the AEC system’s operation would result in the same image quality for all breast thicknesses. This approach to DQE use for AEC system evaluation is independent of the image processing procedure and can be the basis for changes to system calibration done by the manufacturer’s technical support team.

Tackling the commissioning of a digital radiography AEC system

AEC devices aim to maintain a consistent level of clinical image quality despite variations in patient body habitus and imaging method. The assessment of AEC performance has undergone significant revision with the advent of digital radiography and challenges still remain. Verification of manufacturers’ target detector air kerma (DAK) values with differing AEC testing protocols can be problematic, particularly when the system has been configured with integrated direct digital radiography (DDR) detectors. In addition, there is a need for comparative dose information from current DDR technology to be made available to the wider Medical Physics community. AEC testing was performed on 4 recently-installed Carestream DRX Evolution Plus digital radiographic systems as part of their commissioning tests. AEC calibration was assessed using 3 IPEM-recommended parameters; DAK, image pixel value and detector dose indicator (DDI). Testing was performed with both free and scatter-free configurations and with and without antiscatter grid. A mixture of exit dose and in-bucky measurements were performed with the assistance of a field service engineer (FSE) for both free and integrated detectors. Results from the AEC testing of the four Carestream digital radiographic systems are presented for different testing conditions along with hints and tips on assessing the AEC dose levels when commissioning the systems. DAK results are compared to the manufacturers target values and to Bowden et al.’s (2011) published results on other DDR systems. These results could be used as initial AEC reference values against which others can compare their results when commissioning comparable systems.

Radiation dose exposure in patients affected by lymphoma undergoing repeat CT examinations: how to manage the radiation dose variability.

To assess the variability of radiation dose exposure in patients affected by lymphoma undergoing repeat CT (computed tomography) examinations and to evaluate the influence of different scan parameters on the overall radiation dose. A series of 34 patients (12 men and 22 women with a median age of 34.4 years) with lymphoma, after the initial staging CT underwent repeat follow-up CT examinations. For each patient and each repeat examination, age, sex, use of AEC system (Automated Exposure Control, i.e. current modulation), scan length, kV value, number of acquired scans (i.e. number of phases), abdominal size diameter and dose length product (DLP) were recorded. The radiation dose of just one venous phase was singled out from the DLP of the entire examination. All scan data were retrieved by our PACS (Picture Archiving and Communication System) by means of a dose monitoring software. Among the variables we considered, no significant difference of radiation dose was observed among patients of different ages nor concerning tube voltage. On the contrary the dose delivered to the patients varied depending on sex, scan length and usage of AEC. No significant difference was observed depending on the behaviour of technologists, while radiologists' choices had indirectly an impact on the radiation dose due to the different number of scans requested by each of them. Our results demonstrate that patients affected by lymphoma who undergo repeat whole body CT scanning may receive unnecessary overexposure. We quantified and analyzed the most relevant variables in order to provide a useful tool to manage properly CT dose variability, estimating the amount of additional radiation dose for every single significant variable. Additional scans, incorrect scan length and incorrect usage of AEC system are the most relevant cause of patient radiation exposure.

EFFECT OF PATIENT SIZE, ANATOMICAL LOCATION AND MODULATION STRENGTH ON DOSE DELIVERED AND IMAGE-QUALITY ON CT EXAMINATION.

To study the effect of patient size, anatomical location and modulation strength (MS) on image-quality and delivered dose of CT scans acquired with automatic-exposure-control system (AEC). Four anthropomorphic phantoms (three paediatric and one thin adult) were studied, and normal and obese adults were simulated by placing bolus plates around the adult phantom. Thorax and abdomen-pelvis CT were performed using an AEC system equipped with five possible MS. Modulated tube current (mAsmod) was compared to Reference mAs and image-noise was assessed. Effective-mAs were lower than Reference-mAs for all but the obese phantom. However, reversal points were estimated for an effective diameter of 27.8 cm in thorax and 26.9 cm in abdomen-pelvis scans, beyond which the patterns of MS were inversed. mAsmod were dependent on attenuation differences among distinct anatomical location. Finally, dose delivered was associated to the mAsmod and patient's size, with both affecting image-quality.

ASSET BASED COMMUNITY DEVELOPMENT AS A METHOD TO STRENGTHEN ASEAN ECONOMIC COMMUNITY

Indonesia as ASEAN member already binds to ASEAN Economic Community as consequences of Indonesia membership. It means, Indonesia have to apply the liberalization in goods trade whether for import goods or for export goods. As a goal and based on the goal set up by ASEAN Economic Community, the single market should be the way to prosperous people economic. The question is how to achieve this goal instead of pushing or destroying local goods from export goods. It needs to straight up the vision, back to previous goal, and take action to strengthen power or advantages from goods and from AEC system. One of the ways to achieve it is with Asset Based Community Development. This paper will analyze Asset Based Community Development as a means to strengthen ASEAN Economic Community. In Part I, this paper will examine the concept of ASEAN Economic Community. Part II will analyze further on what are the steps of Asset Based Community Development required in intensifying ASEAN Economic Community, and Part III is conclusion.

Getting started with protocol for quality assurance of digital mammography in the clinical centre of Montenegro.

The purpose of this work is (i) to work out a test procedure for quality assurance (QA) in digital mammography with newly released test equipment, including the MagicMax mam multimeter (IBA, Germany) and the anthropomorphic tissue equivalent phantom Mammo AT (IBA, Germany), and (ii) to determine whether a first digital computer radiography (CR) system in Montenegro meets the current European standards. Tested parameters were tube output (µGy mAs(-1)) and output rate (mGy s(-1)), reproducibility and accuracy of tube voltage, half value layer, reproducibility and accuracy of the AEC system, exposure control steps, image receptor's response function, image quality and printer stability test. The evaluated dosimetric quantity is the average glandular dose (AGD) as evaluated from PMMA slabs simulating breast tissue. The main findings are that QA can be organised in Montenegro. (1) All measured parameters are within the range described in European protocols except the tube voltage which deviated more than ± 1 kV. The automatic determination of the HVL was satisfactorily. AGD ranged from 0.66 to 7.02 mGy for PMMA thicknesses from 20 to 70 mm, and is in accordance with literature data. (2) The image quality score as obtained with the anthropomorphic tissue equivalent phantom Mammo AT for the CR system was similar to findings on the authors' conventional screen-film mammography. (3) In clinical practice the mammograms are printed. The CR reader produces images with a pixel size of 43.75 µm, which is compatible with the laser printer (39 µm laser spot spacing). The image processing algorithm embedded in the reader successfully processes mammograms with desirable image brightness and contrast in the printed image. The authors conclude that this first digital mammography system seems a good candidate for breast cancer screening applications.

SU‐E‐I‐86: Evaluation of the New RaySafe Unfors X2 Dosimetry System

Purpose:To evaluate the new RaySafe Unfors X2 (X2) dosimetry system and compare it to the operation of the RaySafe Unfors Xi (Xi) and Radcal Accugold (RCAG) dosimetry systems. The comparison was done for the radiographic/fluoroscopic detectors, mammography detectors and the CT ionization chambers.Methods:This study used several R/F rooms, GE AMX4 portable x‐ray unit, Siemens Biograph 16 slice CT scanner and a Hologic Dimensions mammography unit to evaluate the dosimetry systems. The three X2 detectors were compared to similar detectors of the older Xi and RCAG detectors under clinical conditions used for diagnostic medical physics testing. Measurements of kVp, HVL and exposure were made under identical conditions.Results:For radiography and fluoroscopy the three systems agreed to within +2 kVp in the 60 to 140 kVp range, HVL measurements agreed to within +2 mm Al and the exposures agreed to within +5%. The RCAG 6 cc ionization chamber measured at least 3% higher than the diode systems. The X2 R/F detector appeared to be transparent to the fluoroscopy AEC system. For exposures made using both the CT ACR dose phantoms, the X2 agreed to within +3% of the other two systems. For mammography measurements, the three systems agreed to within +0.4kVp (25‐49 kVp range), HVL measurements agreed to within +0.05 mm Al and the exposures agreed to within +1% of the ionization chamber.Conclusion:The X2 system is a new version of the older Xi system. The system is faster, more robust, very easy to use, has a larger dynamic range, produced less errors and stores 1000 exposures. The measurements showed that the system performs well in the clinical environment and the X2 is within + 5% agreement of the other two calibrated systems.

Survey of compliance with European acceptability criteria for HVL and AEC

Half value layer (HVL) was measured for 226 general radiographic X-ray tube assemblies at 80 kV and for 53 dental X-ray tube assemblies at 70 kV, and evaluated by the previous (1997) and the new draft of European acceptability criteria (2009) for HVL as adopted from the IEC collateral standards. Fourteen per cent of the tested general radiography X-ray tube assemblies were subject to readjustment by the new criteria. In routine quality control tests, receptor entrance dose was estimated for 54 AEC systems by using post-exposure mAs values, taking into account the measured tube output at different tube potentials, HVL and estimated scattering for 10, 15 and 21 cm PMMA phantom. Receptor dose (third quartile) varied from 6.4 μGy at 60 kV to 3.8 μGy at 125 kV. The results correspond well to the draft criteria for maximum receptor dose of 10 μGy and for the patient thickness compensation.

The HVL in soft tissue and the AAPM and IEC exposure indices

Manual exposure settings for radiographic projections were once based on a points system which assumed that the HVL in soft tissue is 3.0 cm and that each change of 1.0 cm of soft tissue corresponded to a change of 25% in image receptor dose. A set of mAs steps and equivalent kVp steps was estimated that would give appropriate technique factors for changes in patient thickness. With the advent of rare-earth screen-film systems and AEC systems the points system fell into disuse. Screen-film imaging systems have almost entirely been replaced by CR or DR systems and recently, standardised exposure indices have been recommended by the AAPM and IEC to provide exposure guidance for these systems. If the fundamental assumptions on which the points system was based are still valid for modern high-frequency generators and digital imaging systems, then there would be an elegant correspondence between the predictions of the points system and the requirements for correction of exposure errors indicated by the AAPM and IEC indices. This study estimated the HVL and attenuation per cm in soft tissue using computer simulation, finding that practically, the HVL is between 2.0 and 5.0 cm and attenuation per cm ranges from 15 to 25%. The study concluded that agreement between the points system predictions and the true effects of technique factors changes on dose to the image receptor was moderately good, that use of the points system and technique charts based on this system should be encouraged and that use of the IEC or AAPM digital exposure indices should be standardised.

A preliminary study into performing routine tube output and automatic exposure control quality assurance using radiology information system data

Data are currently being collected from hospital radiology information systems in the North West of the UK for the purposes of both clinical audit and patient dose audit. Could these data also be used to satisfy quality assurance (QA) requirements according to UK guidance? From 2008 to 2009, 731 653 records were submitted from 8 hospitals from the North West England. For automatic exposure control QA, the protocol from Institute of Physics and Engineering in Medicine (IPEM) report 91 recommends that milliamperes per second can be monitored for repeatability and reproducibility using a suitable phantom, at 70-81 kV. Abdomen AP and chest PA examinations were analysed to find the most common kilovoltage used with these records then used to plot average monthly milliamperes per second with time. IPEM report 91 also recommends that a range of commonly used clinical settings is used to check output reproducibility and repeatability. For each tube, the dose area product values were plotted over time for two most common exposure factor sets. Results show that it is possible to do performance checks of AEC systems; however more work is required to be able to monitor tube output performance. Procedurally, the management system requires work and the benefits to the workflow would need to be demonstrated.

γ-Alumina Doped Alginate Gel for Cell Immobilization in Fermentation Processes

γ-Alumina (γ-Al 2 O 3 ) doped alginate gel (AEC) was developed as a cell carrier in fermentation processes of Saccharomyces cerevisiae M.30 for ethanol production and Clostridium butyricum DSM 5431 for 1,3-propanediol production. In a single batch system of ethanol fermentation, the final ethanol concentration of suspended cell (SC), immobilized cell on γ-Al 2 O 3 (AC) and AEC cultures were 82.4, 77.1 and 74.6 g/l, respectively. In 4-cycle repeated batch fermentation, the AEC culture demonstrated a good potential of reusability. Its ethanol production and conversion yield of the 1st, 2nd and 3rd repeated batch were comparable to those of the SC and AC cultures with the immobilization yield of 86%. AEC was also found to be effective for the cell immobilization of C. butyricum with the immobilization yield of 83%. However, the strong inhibition effect of cell-γ-Al 2 O 3 immobilization towards 1,3-propanediol production was observed. Moreover, 1, 3-propanediol fermentation stability in the SC, AC and AEC systems tended to be lowered during the repeated batch fermentation. Interfering of positive charge of γ-Al 2 O 3 on the cell membrane was thought to be the cause of the inactivity of C. butyricum DSM 5431 in 1,3-propanediol production.

Basic tests in mammography as a tool in quality improvement

Background Mammography is a radiological diagnostic method which relies on an X-ray examination of breasts and is a process involving the use of low-dose amplitude-X-rays (usually around 0.7 mSv). Combining the use of small doses and high quality images requires extensive quality protocols, part of them being included in regulations adopted by the Minister of Health. Aim The aim of this study was to check the usefulness and efficacy of selected quality tests associated with mammography. Material/methods The study was performed in the mammography service of the Greater Poland Cancer Centre in Poznan. Following equipment was used: densitometer, sensitometer, mammographic scales, electronic scales, thermometer, hygrometer, PMMA plates, Europhantom, screen film contact phantom, viewing boxes and magnifying glasses. The methods were based on basic mammography tests. Quality control in mammography demands: clean darkroom, marked and clean cassettes, clean viewing boxes with homogenous light. Results The results of the “Development Process” test show that each sensitometer has to be used with an appropriate densitometer. Phantoms with abnormal structures cannot be used to “AEC System – Solidity exposure” test. “Compression – The force of compression” test may only be carried out with suitable scales and compressible material. Analysis of rejected films shows that the main reasons for rejection were wrong collimation and underexposure. Conclusion Every quality control in mammography provides essential information about the functioning of a laboratory. Apart from recommended standard sterility, it should be remembered that equipment should always be adjusted and repaired.

DTD-free nonlinear acoustic echo cancellation based on independent component analysis

An adaptive acoustic echo cancellation method based on independent component analysis, which can remove nonlinear echo components, is presented. Since this method takes into account the independence between a far-end signal and the echo-cancelled output to cancel acoustic echoes which are independent of near-end signals, it can continue to update AEC parameters even in double-talk situations, thereby improving the cancellation performance. Experiments show that the proposed method provides better performance than the conventional least-mean-square methods for both linear and nonlinear AEC systems without requiring separate double-talk detection (DTD).

An improved post-filter of acoustic echo canceller based on subband implementation

In this paper, an effective post-filter structure for subband-based acoustic echo cancellation (SAEC) is proposed. Compared with the current subband-based post-filters, the proposed one can more consistently suppress the background noise, as well as the residual echoes. To reduce the effects of the distortion of the near-end speech, two alternative modified versions of the post-filter are proposed, which guarantees the quality of speech communications. The proposed post-filters are seamlessly combined with the subband-based AEC system with quite small computational burden. The instrumental evaluation and listening test both demonstrate the superiority of the post-filters.

Automatic exposure control in pediatric and adult multidetector CT examinations: A phantom study on dose reduction and image quality

The aim of this study was to assess the potential of a modern x,y,z modulation-based automatic exposure control system (AEC) for dose reduction in pediatric and adult multidetector CT (MDCT) imaging and evaluate the quality of the images obtained. Five physical anthropomorphic phantoms that simulate the average individual as neonate, 1-, 5-, 10-year old child, and adult were scanned with a MDCT scanner, equipped with a modern AEC system. Dose reduction (%DR) was calculated as the percentage difference of the mean modulated and the preset tube current-time product that is prescribed for standard head and body scan protocols. The effect of the tube potential and the orientation of the topogram acquisition on dose reduction were assessed. Image quality was evaluated on the basis of image noise and signal to noise ratio (SNR). The dose reduction values achieved in pediatric phantoms were remarkably lower than those achieved for the adult. The efficiency of the AEC is decreased at 80 kVp compared to higher tube potentials and for helical scans following an anterior posterior (AP-AEC) compared to a lateral (LAT-AEC) topogram acquisition. In AP-AEC scans, the dose reduction ranged between 4.7 and 34.7% for neonate, 15.4 and 30.9% for 1 year old, 3.1 and 26.7% for 5 years old, 1.2 and 58.7% for 10 years old, and 15.5 and 57.4% for adult. In LAT-AEC scans, the corresponding dose reduction ranged between 11.0 and 36.5%, 27.2 and 35.7%, 11.3 and 35.6%, 0.3 and 67.0%, and 15.0 and 61.7%, respectively. AP-AEC scans resulted in a 17.1% and 19.7% dose increase in the thorax of neonate and the pelvis of the 10-year old phantom, respectively. The variation in the measured noise among images obtained along the scanning z axis was lower in AEC activated compared to fixed milliamperes scans. However, image noise was significantly increased (P<.001) and SNR significantly decreased (P<.001) in most AEC activated compared to fixed milliamperes scans. In conclusion, AEC resulted in a (i) substantial dose reduction, which is less pronounced in children compared to adult, (ii) higher dose reduction in scans following a lateral compared to scans following an anterior-posterior topogram acquisition, (iii) increase of image noise and degradation of SNR in the obtained images compared to the fixed milliamperes technique.

Kindlin-1 Is a Phosphoprotein Involved in Regulation of Polarity, Proliferation, and Motility of Epidermal Keratinocytes

A novel family of focal adhesion proteins, the kindlins, is involved in attachment of the actin cytoskeleton to the plasma membrane and in integrin-mediated cellular processes. Deficiency of kindlin-1, as a result of loss-of-function mutations in the KIND1 gene, causes Kindler syndrome, an autosomal recessive genodermatosis characterized by skin blistering, progressive skin atrophy, photosensitivity and, occasionally, carcinogenesis. Here we characterized authentic and recombinantly expressed kindlin-1 and show that it is localized in basal epidermal keratinocytes in a polar fashion, close to the cell surface facing the basement membrane, in the areas between the hemidesmosomes. We identified two forms of kindlin-1 in keratinocytes, with apparent molecular masses of 78 and 74 kDa, corresponding to phosphorylated and desphosphorylated forms of the protein. In kindlin-1-deficient skin, basal keratinocytes show multiple abnormalities: cell polarity is lost, proliferation is strongly reduced, and several cells undergo apoptosis. In vitro, deficiency of kindlin-1 in keratinocytes leads to strongly reduced cell proliferation, decreased adhesion, undirected motility, and intense protrusion activity of the plasma membrane. Taken together, these results show that kindlin-1 plays a role in keratinocyte adhesion, polarization, proliferation, and migration. It is involved in organization and anchorage of the actin cytoskeleton to integrin-associated signaling platforms.

SU-FF-I-55: Quality Control in Mammography Screening

Purpose: The Romanian legislation in nuclear field regarding radiological protection of persons in the case of radiationmedical exposures introduces the obligatorily implementation of QA programs in radiological practice. In this context, AIHA had a significant role receiving a grant from the Susan G. Komen Breast Cancer Foundation to implement Mammography Training Program in Romania. In this paper, the first results of the application in Romania of European protocols for QC of mammography screening in two representative mammography facilities in Cluj‐Napoca (Institute of Oncology and Clinic District Hospital) are presented. Method and Materials: Between the several components of mammographysystem the QC was focused on the crucial elements such as the film processing and the basic performance of X‐ray equipment (screen‐film contact, phantom images, automatic exposure control system performance and AEC reproducibility, X‐ray beam quality, average glandular dose and radiation output rate). The applied methodology is in accordance with ACR MammographyQuality Control Manual (1999). Results: Characteristic parameters of mammographic and automatic processing units was compared with limiting values given by International Protocols or with the permissible ranges calculated in advance. If the test results fell outside the action limits, the source of the problem had been identified and corrective actions had been taken. The worst deficiencies found in the equipment were related to AEC system and density control setting. Conclusion: The result of this survey shows that QC procedures have a positive effect on the performance of mammography X‐ray equipment and on the production of high quality images. This minimises the possibility of repeating exposures and hence the patient dose. Practical application of such QC program in Romania impose the raise of medical physicist role in clinical activities and the assurance of qualitative service for X‐ray equipment.

Management of pediatric radiation dose using Canon digital radiography

A Canon CXDI-11 digital radiography (DR) system has been in use at Shands Hospital at the University of Florida for the past 2 1/2 years. A first clinical implementation phase was utilized to develop imaging protocols for adult patients, with a second phase incorporating pediatric chest and abdominal studies a few months later. This paper describes some of the steps taken during the modality implementation stages, as well as the methodologies and procedures utilized to monitor compliance by the technologists. The Canon DR system provides the technologist with an indication of the radiation exposure received by the detector (and thus of the patient dose) by means of an indirect exposure level number called the reached exposure (REX) value. The REX value is calculated by the system based on the default grayscale curve preselected for a given anatomical view and used by the system to optimize the appearance of the image. The brightness and contrast of the image can be modified by the user at the QC/control screen for the purpose of improving the appearance of the image. Such changes modify the actual grayscale curve (position and slope, respectively) and thus the calculated REX value. Thus, undisciplined use of the brightness and contrast functions by the technologist can render the REX value meaningless as an exposure indicator. The paper also shows how it is possible to calibrate AEC (phototimer) systems for use with the Canon DR system, and utilize the REX value as a valuable dose indicator through proper training of technologists and strict, disciplined QC of studies. A team consisting of the site's medical physicist, radiologists, and technologists, as well as Canon engineers, can work together in properly calibrating and setting up the system for the purposes of monitoring patient doses (especially pediatric) in DR studies performed in a Canon DR system.

Quality Control in Mammography: Analysis of the Results from a 4 Year Period

The quality control (QC) of the physical and technical aspects of the Breast Screening Programme developed in Galicia (Spain) started in 1993; the QC results from 1993 to 1997 are presented. Measurements related to X ray generation and control how that 100% of the units met the limiting values for most of the parameters included in the European Guidelines. contro show tha 100% of the units me th limiting values for most of the parameters included in the European Guidelines. The failures more frequently found were incorrect alignment of the X ray lield and receptor and incorrect functioning of the AEC system. With respect to image quality (IQ), the values of high contrast resolution keep approximately constant over the 4 years. Thus, it is suggested that this parameter be checked every 6 months instead of weekly. The entrance surface air kerma measured under reference conditions was below the reference value during the whole period for all the screening units.