Topic
Automatic exposure control
About: Automatic exposure control is a research topic. Over the lifetime, 851 publications have been published within this topic receiving 10506 citations.
Papers published on a yearly basis
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Papers
TL;DR: It is recommended that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence and Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important.
Abstract: Computed tomography (CT) technology has changed considerably in recent years with the introduction of increasing numbers of multiple detector arrays. There are several parameters specific to multi-detector computed tomography (MDCT) scanners that increase or decrease patient dose systematically compared to older single detector computed tomography (SDCT) scanners. This document briefly reviews the MDCT technology, radiation dose in MDCT, including differences from SDCT and factors that affect dose, radiation risks, and the responsibilities for patient dose management. The document recommends that users need to understand the relationship between patient dose and image quality and be aware that image quality in CT is often higher than that necessary for diagnostic confidence. Automatic exposure control (AEC) does not totally free the operator from selection of scan parameters, and awareness of individual systems is important. Scanning protocols cannot simply be transferred between scanners from different manufacturers and should be determined for each MDCT. If the image quality is appropriately specified by the user, and suited to the clinical task, there will be a reduction in patient dose for most patients. Understanding of some parameters is not intuitive and the selection of image quality parameter values in AEC systems is not straightforward. Examples of some clinical situation shave been included to demonstrate dose management, e.g. CT examinations of the chest, the heart for coronary calcium quantification and non-invasive coronary angiography, colonography, the urinary tract, children, pregnant patients, trauma cases, and CT guided interventions. CT is increasingly being used to replace conventional x-ray studies and it is important that patient dose is given careful consideration, particularly with repeated or multiple examinations.
1,358 citations
TL;DR: An automatic exposure control mechanism that is based on real-time anatomy-dependent tube current modulation delivers good image quality with a significantly reduced radiation dose.
Abstract: PURPOSE: To prospectively compare dose reduction and image quality achieved with an automatic exposure control system that is based on both angular (x-y axis) and z-axis tube current modulation with dose reduction and image quality achieved with an angular modulation system for multi–detector row computed tomography (CT). MATERIALS AND METHODS: The study protocol was approved by the institutional review board, and oral informed consent was obtained. In two groups of 200 patients, five anatomic regions (ie, the thorax, abdomen-pelvis, abdomen-liver, lumbar spine, and cervical spine) were examined with this modulation system and a six-section multi–detector row CT scanner. Data from these patients were compared with data from 200 patients who were examined with an angular modulation system. Dose reduction by means of reduction of the mean effective tube current in 600 examinations, image noise in 200 examinations performed with each modulation system, and subjective image quality scores in 100 examinations ...
365 citations
Patent•
26 Jul 1995TL;DR: In this article, an automatic exposure imaging system operating on a single-frame image capture basis is adapted for single chip CMOS type construction, which can provide automatic gain control (60), automatic exposure control (64), automatic focus sensing (62) and single frame imaging and decoding, with reduced power consumption.
Abstract: An automatic exposure imaging system (Fig. 2) operating on a single frame image capture basis is adapted for single chip CMOS type construction. For reading dataforms, such as two-dimensional bar codes and matrix codes, the system can provide automatic gain control (60), automatic exposure control (64), automatic focus sensing (62) and single frame imaging and decoding, with reduced power consumption. A fixed focus distance sensor element array assembly (21b) and optical distance sensing enable automatic initiation of exposure when the image is in-focus (Fig. 4). Exposure provided by image illuminators (50, 54) is automatically controlled by sensing of the cumulative level of reflected light during the exposure period (Fig. 6). Alternatively, exposure time is determined from a look-up table (82a), based upon the level of light reflected during an initial illumination period of fixed duration (Fig. 7). Automatic system turn-off or re-reading can be provided, depending upon whether a dataform is successfully decoded (Fig. 6 and 7). Power use is reduced by terminating the reading of sensor elements upon successful decoding. A complete, light-weight, hand-held reader (10) is described, including provison for transmission of decoded dataform information and a wide range of additional capabilities via plug-in cards (34, 36). Related methods are also described.
249 citations
TL;DR: Surfaces doses can be reduced if radiologic technologists can better center patients within the CT gantry and result in as much as 30% reduction in surface dose.
Abstract: OBJECTIVE The purpose of this study was to determine with phantom and patient imaging the effect of an automatic patient-centering technique on the radiation dose associated with MDCTSUBJECTS AND METHODS A 32-cm CT dose index (CTDI) phantom was scanned with 64-MDCT in three positions: gantry isocenter and 30 and 60 mm below the isocenter of the scanner gantry In each position, surface, peripheral, and volume CTDIs were estimated with a standard 10-cm pencil ionization chamber The institutional review board approved the study with 63 patients (36 men, 27 women; mean age, 51 years; age range, 22-83 years) undergoing chest (n = 18) or abdominal (n = 45) CT using the z-axis automatic exposure control technique Each patient was positioned according to the region being scanned and then was centered in the gantry Before scanning of a patient, automatic centering software was used to estimate patient off-centering and percentage of dose reduction with optimum recentering Data were analyzed with linear cor
215 citations
TL;DR: For the evaluated automatic exposure control system, CTDI(vol) (scanner output) increased linearly with patient size; however, patient dose (as indicated by SSDE) was independent of size.
Abstract: For 545 adult patients who underwent CT examinations of the torso and who varied in size by a factor of two, the automatic exposure control system used increased CTDIvol from 12 to 26 mGy, but average estimated patient dose was 22 mGy ±?3, independent of size
182 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 4 |
| 2024 | 4 |
| 2023 | 8 |
| 2022 | 12 |
| 2021 | 20 |
| 2020 | 29 |