Automatic Brightness Control Research Articles

Light sensor based covert channels on mobile devices

The widespread adoption of light sensors in mobile devices has enabled functionalities that range from automatic brightness control to environmental monitoring. However, these sensors also present significant security and privacy risks within the Android ecosystem due to unrestricted access permissions. This paper explores how light sensor data can be used for covert communication through a novel, light-based out-of-band channel. We develop two approaches–Baseline and ResetBased–that use luminance values to encode and decode data. These methods tackle challenges that arise from data variability and the unpredictability of sensor event timings. To enhance data transmission accuracy, our methods employ a novel strategy for selecting luminance reference sequences and leverage mean-squared-error-based distance for decoding. Experimental results validate the effectiveness of our approaches and their potential for real-world applications.

Methodological Considerations for Assessing Automatic Brightness Control in Endoscopy: Experimental Study.

Endoscopy is a critical application that requires adaptable illumination to adjust to varying imaging conditions. Automatic brightness control (ABC) algorithms ensure optimal brightness throughout the image with rapid but smooth response and render the true colours of the biological tissue under examination. To achieve good image quality, high-quality ABC algorithms are necessary. In this study, we propose a three-assessment method approach for objectively evaluating ABC algorithms based on (1) image brightness and its homogeneity, (2) controller response and response time, and (3) colour rendition. We conducted an experimental study to assess the effectiveness of ABC algorithms in one commercial and two developmental endoscopy systems using the proposed methods. The results showed that the commercial system achieved good, homogeneous brightness within 0.4 s, and its damping ratio was 0.597, indicating a stable system, but its colour rendition was suboptimal. The developmental systems had control parameter values that resulted in either a sluggish response (over 1 s) or a fast (about 0.3 ms) but unstable response with damping ratios above 1, causing flickers. Our findings indicate that the interdependency among the proposed methods can establish tradeoffs in the overall ABC performance better than single-parameter approaches. The study establishes that comprehensive assessments using the proposed methods can contribute to designing new ABC algorithms and optimising already implemented ones for efficient performance in endoscopy systems.

Review and investigation of automatic brightness/dose rate control logic of fluoroscopic imaging systems in cardiovascular interventional angiography.

In this article, we review automatic brightness control (ABC) for fluoroscopy imaging systems. Starting from the simple manual control, the discussion is extended to the kV-primary ABC system, and then to the most recent contrast-to-noise ratio optimized (CNR Optimized) automatic dose rate control system (ADRC). The nature of this review article is trifold. First, it describes the ABC/ADRC and associated circuits governing the operation of the fluoroscopy imaging chain. Second, we show the characteristics of a control logic from a radiation physics point of view. Third, we introduce the most recent activities in the evaluation of CNR-optimized fluoroscopy systems and the phantom design that would be compatible with the design concept of the ADRC. Because of these three subject items in the discussion process, this article is also educational in nature written for medical physicists and radiological technologists who might be less familiar with the design concept of fluoroscopy operation, specifically on the ABC and ADRC. We insert a few related matters associated with fluoroscopy automatic control circuits where they seem applicable and appropriate to enhance the understanding of fluoroscopy operation logic.

Brightness of the Screen of Gated Low Light Level Image Intensifier Based on Automatic Brightness Control Model

Brightness of the Screen of Gated Low Light Level Image Intensifier Based on Automatic Brightness Control Model

The use of digital magnification to reduce radiation dose in the cardiac catheter laboratory.

To audit whether using magnification of images by use of a large viewing screen using digital matrix magnification which enlarges the image by 33% without using the X-ray machine zoom magnification protocols on a Siemens Artis Zee X-ray machine in a cardiac catheter laboratory results in a reduction of kerma-area product (KAP) for both diagnostic and interventional procedures. This reduction was predicted in an in vitro study in our laboratory, which has previously shown a 20.4% reduction in KAP. A retrospective analysis was conducted of the radiation exposure to compare the measured KAP recorded during the period when conventional magnification with automatic brightness and dose control was used on a Siemens Artis Zee X-ray machine with a flat panel detector and when magnification settings were avoided by using a large screen to enlarge and project a non-magnified image by digital magnification. The analysis was carried out for patients having a diagnostic coronary angiogram and those having an interventional coronary procedure. For diagnostic coronary angiograms the median KAP per procedure in the period using conventional magnification was 2124.5 µGy.m2 compared to 1401 µGy.m2 when image matrix magnification was used, a 34% reduction (p < 0.0001). For interventional coronary procedures, the median KAP per procedure in the period using conventional magnification was 3791 µGy.m2 compared to 2568.5 µGy.m2 when image matrix magnification was used, a 32% reduction (p < 0.0001). Avoiding using conventional magnification in the cardiac catheter laboratory and using a large screen to magnify images was associated with a statistically significant greater than 30% reduction in KAP. This paper is the proof in clinical practice of a theoretical conclusion that radiation dose (KAP) is reduced by use of Image matrix magnification using a large viewing screen without the need to use X-ray tube magnification without significant loss of image resolution in interventional cardiology. The same approach will be useful in interventional radiology.

Reduced radiation fluoroscopy technique for implantation of sacral neuromodulation

Introduction: Sacral neuromodulation (SNM) is a Food and Drug Administration–approved treatment option for urinary urgency and fecal incontinence. Fluoroscopic imaging is used at various steps during lead placement, which exposes the operating room staff and patient to the harmful effects of radiation. The aim of this study is to describe a reduced radiation technique during lead placement for treatment with SNM. Methods: A retrospective cohort of 51 consecutive patients who underwent lead insertion and SNM placement at a single academic institution were investigated. Reduced fluoroscopy (RF; n=11) involved C-arm settings to 1 pulse/second and an activated “low-dose” setting, while conventional fluoroscopy (CF; n=40) involved 30 pulses/second and a deactivated “low-dose” setting. The automatic brightness control and collimation were used optionally in both groups. Comparison of imaging quality, fluoroscopy settings, and radiation exposure during RF and CF was performed. Results: RF settings resulted in significant reduction of radiation compared to CF settings, including the fluoroscopy time (8.61 vs. 48.16 seconds; p&lt;0.001), dose (2.66 vs. 26.25 mGy; p=0.001), and current (1.67 vs. 4.18 mAs; p&lt;0.001). There was no significant difference in total operative time (59.18 vs. 61.33 minutes; p=0.77) and the rate of progression from stage 1 to stage 2 during follow-up (75% vs. 84%; p=0.55). Conclusions: Lead placement for treatment with SNM can be achieved using RF settings without compromising clinical outcomes. Applying the RF technique reduces overall radiation exposure to the patient and the operating room staff. Further validation of RF in a larger prospective cohort study is needed. Level of evidence: Level 4.

The Effect of Operative Field Instrument Clutter During Intraoperative Fluoroscopy on Radiation Exposure.

Introduction and Objectives: Fluoroscopy units are routinely operated in the automatic brightness control (ABC) mode to optimize image quality. During ureteroscopy, objects may be placed within the fluoroscopy beam and the effect upon radiation exposure is unknown. The purpose of this study is to investigate the effects of equipment within the fluoroscopy beam during simulated ureteroscopy. Methods: ABC fluoroscopy of a cadaver was performed in eight clinical scenarios, including a control (no equipment), and seven groups with different equipment within the fluoroscopy beam. Equipment tested included electrocardiogram (EKG) leads, a Kelly clamp, camera and light cords (straight and coiled configurations), flexible ureteroscope, rigid cystoscope, and the lateral table support beam. Ten 145-second fluoroscopy trials were performed for each arm. The primary outcome was radiation dose (mGy) compared using the Mann-Whitney test with p < 0.05 considered significant. Results: Compared with control (18.5 mGy), radiation exposure was significantly increased with the presence of a straight camera and light cords (19.3 mGy), Kelly clamp (19.4 mGy), coiled camera and light cords (20.2 mGy), a flexible ureteroscope (21.0 mGy), a rigid cystoscope (21.2 mGy), and when the lateral table support beam was in the path of the X-ray (25.0 mGy; a 35% increase; p < 0.007 for all). The EKG leads did not affect the radiation dose. Conclusions: Avoiding equipment within the fluoroscopy beam using ABC mode can reduce radiation exposure. Adjusting the table and patient position to exclude the lateral table support beam will reduce radiation exposure by 35%.

Optimisation of on-board imaging fluoroscopy

On-board imaging fluoroscopy is used for localisation of the target immediately prior to external beam radiotherapy. The feature is clinically used for lung stereotactic ablative radiotherapy involving a moving target and high dose per fraction. Use of fluoroscopy is clearly justified, allowing verification that the target is within the field over its range of motion, ensuring the tumour is not under-treated and there is not excessive dose to normal tissue. Commissioning the fluoroscopy features on Varian Clinacs and Varian Truebeams demonstrated that systems are not optimal at installation. The ability to adjust the automatic brightness control settings is not readily available and access required extensive discussions with the manufacturer. The TrueBeam linear accelerator had additional dose reduction features not available on the Clinac. Such features available in clinical mode included the ability to adjust pulse rate settings and add additional titanium filtration This paper will detail the potential for significant patient dose reduction (35 mGy/min to 16 mGy/min Clinac, 75 mGy/min to 8 mGy/min Truebeam) without a clinically significant reduction in image quality. The doses post optimisation are below what would be expected from an image intensifier and slightly higher than what would be typical for a modern flat-panel interventional system. The dose comparisons are made to interventional systems due to the lack of published data in radiotherapy systems. Historically the focus has been on the considerably higher radiotherapy dose, but recent developments and increased use of imaging in therapy has seen increased attention to imaging doses.

Analysis of Importance of Lighting Factors through Kano Model and AHP

The technology to control and manage the light environment is making gradual progress, but unclear is the criterion of actual users’ satisfaction with what factors, and what factors should be preferentially considered as being important.BR Hereupon, this study deducted the importance of lighting factors reflecting the opinion of general consumers and lighting-related experts through Kano Model and AHP.BR As a result, this study deducted that the first things to be solved in lighting & control system development are energy reduction, human body fitness, and economic efficiency. Consequently, it’s necessary to minimize power consumption and standby power, to arrange and apply the standard of photobiological safety of LED lighting, and also to make the plan for the lowering of initial purchase cost.BR Along with this, it’s necessary to provide brightness and color temperature suited for space or behavior, and to develop & provide various contents through convergence of lighting, IT, and IoT, etc. Also, it’s necessary to achieve automatic brightness control through human body sensing in connectionwith a sensor, and to make it possible for a user to be able to adjust brightness of lighting and to easily exchange and install the light source, or control system.

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.

Effect of C-Arm Year Model on Radiation Scatter

Since the 1980’s C-arm fluoroscopy has been an integral part of orthopaedic trauma surgery. The advancement in C-arm technology has resulted in different generations of C-arms co-existing in the operating rooms. The purpose of this study was to compare the radiation scatter patterns of different generation C-arms. Three generation of C-arms were tested: GE OEC 9800 Plus (1999/2000), Siemens Arcadis Orbic 3D (2004), Philips BV Pulsera 2.3 (2008). Radiation scatter was measured using six real-time dosimetry badges set up on either side of the surgical table (Mizuho OSI, flat-top). Distance of C-arm was normalized at 20 in. and 10 in. from Image Intensifier. Each device was set to the automatic brightness control (ABC) setting. A phantom limb was irradiated for 120 s and radiation scatter was summed for both AP and lateral positions. At their typical operating room settings there was a reduction in radiation scatter using the newer generation C-arms. Results for total radiation, normalized to Philips, are as follows: Philips 1 (100%), GE 2.4 (240%), and Siemens 1.4 (140%). Newer generation C-arms can be expected to generate lower radiation scatter. Special care should be taken to attempt a lower dose setting, especially when utilizing older generation C-arms to minimize radiation scatter to practitioner.

42.2: Invited Paper: Ambient Light Levels During Television Viewing

AbstractThe Energy Star Program Requirements for Televisions Version 5 test procedures for Automatic Brightness Control (ABC) enabled televisions' required power measurements at 0 Lux and 300 Lux of ambient light incident on the television screen.In 2010 the Collaborative Labeling and Appliance Standards Program (CLASP) funded a study to assess how accurately Energy Star Version 5 quantifies actual residential television energy use. The results of that study indicated that the specified Energy Star illuminance levels for power measurements of televisions with the ABC feature enabled may not accurately represent actual light levels during television viewing.In 2011 CLASP funded the California Lighting Technology Center (CLTC) to measure actual ambient light levels during television viewing in 60 homes over seven days.The results of the CLTC study show the television light sensor measured illuminance levels from less than 1 lux to more than 300 lux (lx). The vast majority of viewing (79.5%) occurred at illuminance levels below 50 lx, while very little viewing (3.6%) occurred at illuminance levels greater than 300 lx. The results of this study indicate that 0 lx illuminance is unnecessary and that other illuminance levels (10, 50, and 100 lx) should be considered for power measurements, to better reflect actual illuminance levels during TV viewing in residential applications.

Schematic development solutions automatic brightness control oleds glow.

В работе предложена методика измерения яркости органической светоизлучающие структуры и разработаны схемотехническое решение для автоматического регулирования яркости свечения органического светодиода в зависимости от освещенности помещения. Смоделирован и оптимизирован схему электрическую принципиальную в программной среде Proteus. Предложенная схема позволяет оптимизировать работу светоизлучающего устройства и за счет использования органических светодиодов и системы их регулирования снизить энергопотребление.

自动亮度控制对微光电视系统强光适应性的影响

自动亮度控制对微光电视系统强光适应性的影响

In Automated Fluoroscopy Settings, Does Shielding Affect Radiation Exposure to Surrounding Unshielded Tissues?

Automatic brightness control (ABC), a function of modern fluoroscopy machines, adjusts radiation intensity in real time to enhance image quality. While shielding reduces radiation exposure to protected areas, it is unknown how much radiation adjacent unshielded areas receive when using ABC settings. Our purpose was to assess radiation dosage to shielded and unshielded tissue when using fluoroscopic ABC mode compared with fixed exposure settings. In a simulated ureteroscopy, thermoluminescent dosimeters (TLDs) were placed at three sites in a female human cadaver, including the right renal hilum, right distal ureter adjacent to the uterus, and directly over the uterus. The cadaver received 60 seconds of radiation exposure using a C-arm fluoroscopy system under ABC and fixed settings (1.38 mAs, 66 kVp) with and without uterine shielding. Radiation dosage absorbed by the TLDs was compared using two-way analysis of variance and least-squares confidence intervals. Shielding significantly reduced radiation dose to the uterus by 62% and 82% (P<0.05 for both) in ABC and fixed settings, respectively. Shielding of the uterus in ABC, however, resulted in an approximately twofold increase in radiation dosage to the ureter and ipsilateral kidney (P<0.05 for both) and a decrease in image quality. Using fixed settings, shielding of the uterus did not increase radiation dose to the ipsilateral ureter and kidney. There is a significant increase in radiation dosage to surrounding tissues when shielding is used with ABC mode during fluoroscopy. Radiation can be reduced and image quality improved by using fixed settings when shielding is indicated.

MO‐E‐204B‐09: A Method to Evaluate the Effect of Automatic Brightness Control Tracking on Image Quality and Patient Dose for Interventional Fluoroscopic Systems

Purpose: Automatic‐brightness‐control (ABC) tracking is used to maintain a constant image‐receptor signal independent of changes in the attenuation of the patient. The manner of tracking impacts image quality as well as patient dose. We have developed a procedure to evaluate the effect of the ABC‐operation logic on both dose and contrast‐signal‐to‐noise ratio (CSNR) for interventional‐ fluoroscopic systems. Method and Materials: Two vascular‐angiography systems, one with an image intensifier (II) and the other with a flat‐panel detector (FPD), were used for assessment of the testing procedure. A phantom insert containing iodine‐filled disks was sandwiched within a variable‐thickness, uniform PMMA phantom. The variation of contrast visibility and patient dose was assessed as the ABC system automatically adjusted technique parameters to compensate for changes in phantom thickness. The x‐ray techniques, filter selected by the system, acquisition rate, patient entrance exposure and detector input exposure were recorded as a function of phantom thickness. The CSNR and CSNR per entrance exposure were plotted as a function of phantom thickness for all fluoroscopic modes. Results: All systems and modes had a decrease in CSNR and an increase in dose with patient thickness, but different modes resulted in different rates of change due to the manner of mAs and kVp selection. Although noise varied between fluoroscopy modes for the II and FPD, it was almost constant for a given mode as a function of thickness since the ABC tries to maintain a constant detector exposure rate. Conclusion: The method is easy to implement with a standard phantom and is an important adjunct to evaluate ABC system performance and to allow inter‐system comparisons. Understanding the tradeoffs between patient dose and CSNR due to the operation of a specific ABC mode can help optimize system utilization.

SU-GG-I-61: Variation of Effective Dose with Projection Angle during Cardiac-Catheterization Imaging

Purpose:Cardiac catheterization is a high‐dose x‐ray imaging procedure that includes several radiosensitive organs in the beam. This work demonstrates the variation of effective dose with projection angle for this procedure. Methods and Materials: ICRP 103 effective doses were calculated using PCXMC 2.0 for the geometry of simulated cardiac procedures with the Toshiba Infinix C‐Arm unit equipped with a 20 × 20 cm flat‐panel detector (FPD). With the heart at isocenter, effective dose was calculated per mAs for cranial/caudal (CRA/CAU) angles from 50° CRA to 50° CAU and left‐anterior oblique / right‐anterior oblique (LAO/RAO) projection angles from 90° LAO to 90° RAO from the posterior‐anterior (PA) direction. An estimate of view effective dose was made using technique parameters that were recorded for cardiacimaging of a Rando torso phantom at various projection angles with the unit operating under automatic brightness control. Results: Effective dose per mAs values are seen to peak at an LAO/RAO angle of about 30 degrees and drop rapidly as the beam moves more laterally, with a reduction of about 60% at 90 degrees. A decrease of about 20% is seen as the CRA/CAU angle is increased. With the phantom, there was an increase in technique parameters with increasing projection angle that tends to offset the effective dose per mAs decrease, so that the view effective dose generally increases with angle. Conclusion: The stochastic risk increment to the patient as reflected in the effective dose varies with the projection view used during the cardiac‐catheterization procedure. In general, the more that larger CRA/CAU and RAO/LAO angles are used, the greater will be the cumulative effective dose. (Support: Toshiba Medical Systems Corporation)

蛍光ガラス線量計を用いたＩＶＲ装置の実効エネルギーと入射表面線量の測定（半価層測定器と測定用ファントムの作製）

In interventional radiology (IVR) procedures, automatic brightness control (ABC) is helpful in maintaining good image quality by adjusting kV and/or mA based on the subject's thickness. However, it was difficult to measure effective energy using half-value layer (HVL). We investigated the usefulness of measuring effective energy and entrance surface dose using a fluorescent glass dosimeter in IVR procedures, and we made an HVL folder and IVR-phantom for that purpose. Effective energy measured using the HVL folder correlated well with reference ionization dosimeter (y=0.992x, r=0.963). The result indicated that the present method using an HVL folder and IVR-phantom provides accurate measurements of effective energy and entrance surface dose in IVR procedures. In conclusion, the present measurement method may be useful for quality control of IVR equipment. In addition, the development of this measurement technique may be useful for comparisons of exposure levels in different hospitals.

Does digital flat detector technology tip the scale towards better image quality or reduced patient dose in interventional cardiology?

As dynamic flat-panel detectors (FD) are introduced in interventional cardiology (IC), the relation between patient dose and image quality (IQ) needs to be reconsidered for this type of image receptor. On one hand this study investigates IQ of a FD system by means of a threshold contrast-detail analysis and compares it to an image intensifier (II) system on a similar X-ray setup. On the other hand patient dose for coronary angiography (CA) procedures on both systems is compared by Dose-Area Product (DAP)-registration of a patient population. The comparative IQ study was performed for a range of entrance dose rates (EDR) covering the fluoroscopy and cinegraphy working mode. In addition the IQ investigation was extended to a similar study under automatic brightness control (ABC). As well the systematic study of IQ as a function of EDR as the study performed under ABC point to a better IQ for FD in cinegraphy mode and no difference between both systems in fluoroscopy mode. The patient population study resulted in mean DAP values of 31 Gy cm 2 (II system) and 33 Gy cm 2 (FD system) ( p = 0.68) for CA procedures. As well total DAP as contributions of fluoroscopy and cinegraphy on both systems are not significantly different. To conclude, we could state that profit was taken from the intrinsic better performance of the FD for cinegraphy mode in producing higher quality images in this mode but without any effect on patient dose for CA procedures.

SU‐GG‐I‐84: Operation Logic of Coventional FluoroscopyAutomatic Brightness Control

Purpose: New generation of fluoroscopic imaging systems are equipped with spectral shaping filters complimented with sophisticated automatic brightness (and image quality) control logic called fluoroscopy curve or trajectory. Such fluoroscopy curves were implemented first on cardiovascular systems, and are now available on conventional fluoroscopy equipment. This study is to investigate the control logic operations under the fluoroscopy and spot filming/acquisition modes of a conventional fluoroscopy system typically installed for Upper‐Lower GI Examination Suites, Interventional Endoscopy Laboratory, Gastrointestinal Laboratory and Pain Clinics. Method and Materials: A brand new GE Precision 500D fluoroscopy system was chosen for the investigation which was installed in the middle of February 2008. Two radiation detectors were employed to monitor the patient and image intensifier air kerma dose and dose rate as functions of increasing PMMA plastic phantom thickness. The measurement protocol utilized by the AAPM TG 125 was followed as much as possible with some exceptions due to the mechanical constraints. The image quality was evaluated with the NEMA‐SCAI phantom at 4″, 8″, and 12″ total phantom thicknesses. Results: The data analysis and the graphs obtained from this study showed extensive use of copper filters (up to 0.3 mmCu) similar to the cardiovascular imaging systems (up to 0.9 mmCu). However, it is with fewer steps of copper filters and less power input to the x‐ray tube, reflecting the differences of clinical applications, and complexity of examinations. As expected, it also showed somewhat narrower dynamic range the imaging system is able to cover with reasonable “penetration” as opposed to that of cardiovascular imaging systems. Conclusion: It is shown that compared against previous generations of fluoroscopy systems, the new conventional fluoroscopy systems equipped with spectral shaping filters provide reduced patient dose while maintaining reasonable (better than just acceptable) image quality. In‐depth discussion will be provided at the presentation.