How I Do It: Managing Radiation Dose in CT

Mayo-Smith, William W.; Hara, Amy K.; Mahesh, Mahadevappa; Sahani, Dushyant V.; Pavlicek, William

doi:10.1148/radiol.14132328

Cited by 167 publications

(94 citation statements)

References 66 publications

(67 reference statements)

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“…In a phantom study by Scholten et al (18) substantial differences in absolute percent error were observed between −800 and −630 HU densities for 5 and 10 mm in diameter spherical nodules, based on CT scans reconstructed with filtered back projection (FBP). It is not clear what the effect on measurement error would be for non-spherical nodules at these sizes and densities, or for CT scans reconstructed using iterative reconstruction (IR) algorithms, which have re-emerged in clinical scanners as part of the ongoing effort to reduce patient radiation exposure while maintaining image quality (19,20). Different types of IR include adaptive (or statistical as they are sometimes referred to) algorithms, which use predictor models of statistical noise in iterative procedures to reduce noise on FBP reconstructed scans, and model-based algorithms which incorporate more complex system models of data statistics, X-ray physics, and system optics in the image reconstruction process (21).…”

Section: Introductionmentioning

confidence: 99%

Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study

Gavrielides

Berman

Supanich

et al. 2017

Quant. Imaging Med. Surg.

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Background: To assess the volumetric measurement of small (≤1 cm) nonsolid nodules with computed tomography (CT), focusing on the interaction of state of the art iterative reconstruction (IR) methods and dose with nodule densities, sizes, and shapes. Results: Density had the most important effect on measurement error followed by the interaction of density with nodule size. The nonsolid −630 HU nodules had high accuracy and precision at levels comparable to solid (−10 HU) nonsolid, regardless of reconstruction method and with CTDI vol as low as 0.6 mGy. PB was <5% and <11% for the 10-and 5-mm in nominal diameter −630 HU nodules respectively, and RC was <5% and <12% for the same nodules. For nonsolid −800 HU nodules, PB increased to <11% and <30% for the 10-and 5-mm nodules respectively, whereas RC increased slightly overall but varied widely across dose and reconstruction algorithms for the 5-mm nodules. Model-based IR improved measurement accuracy for the 5-mm, low-density (−800, −630 HU) nodules. For other nodules the effect of reconstruction method was small. Dose did not affect volumetric accuracy and only affected slightly the precision of 5-mm nonsolid nodules.Conclusions: Reasonable values of both accuracy and precision were achieved for volumetric measurements of all 10-mm nonsolid nodules, and for the 5-mm nodules with −630 HU or higher density, when derived from scans acquired with below screening dose levels as low as 0.6 mGy and regardless of reconstruction algorithm.

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Section: Introductionmentioning

confidence: 99%

Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study

Gavrielides

Berman

Supanich

et al. 2017

Quant. Imaging Med. Surg.

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“…First, turning the standard CT protocols in LD/ULD-CT protocols it is not benevolently accepted at the beginning. Radiologists and referring physicians have been educated to read a pretty image reconstructed with filtered-back-projections (FBP) generated with a standard dose and do not easily accept sudden changes in their habits [13,14]. Second, the conversion of some radiographic studies into LD/ULD-CT will result in a workload increase at CT scan, especially in the radiology departments with only one scanner.…”

Section: Short Communicationmentioning

confidence: 99%

“…The majority of radiologists were not thoroughly familiar with tube parameters and methods to optimize the radiation dose and image quality [13]. Working together with the medical physicist improved the radiologists' knowledge about methods of CT radiation safety and motivated both professionals.…”

Section: Implementation Of the Ct Dose Reduced Protocols: A Long Processmentioning

confidence: 99%

Facing Radiologists' Reluctance of a Degraded although Diagnostic Image Quality of Low/Ultra-low-dose CT: Our Experience

Macrì¹,

Khasanova²,

Greffier³

et al. 2016

OMICS J Radiol

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The radiological community is endeavouring to raise the awareness about the radiation-induced cancer. Computed Tomography (CT) is the main source of medical irradiation. Manufacturers provided efficient technological tools on CT to achieve a significant radiation dose reduction while maintaining a diagnostic quality of the image. Yet, the implementation of all these improvements allowing the low-dose (LD) and ultra-low-dose (ULD) CT imaging has difficulty to take hold. Radiologists do not easily accept to read images with a degraded image quality although diagnostic. As every cultural change, even in a radiological department the acceptation of the LD/ULD-CT imaging requests time. Constant meetings with substantial exempla and constructive discussions among radiologists, without abrupt modifications to the CT protocols in clinical practice, are the key to the success.

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“…Pitch is calculated as a proportion between the table feed, expressed in centimetres per full rotation of the gantry, and the total width of collimated x-ray beam along the z direction [35]. When increasing the pitch while keeping the tube current per unit of time constant as the table moves, the radiation dose is decreased.…”

Section: Introduction 27mentioning

confidence: 99%

Image Analysis and Visualization of the Human Mastoid Air Cell System

Cros¹

2015

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Legend: CO cochlea, EC ear canal, FN facial nerve, MACS mastoid air cell system, MC micro-channels, OSS ossicles (manubrium of the incus), TM tympanic membrane, TS trabecular spaces, TYM tympanum (middle ear). Image Analysis and Visualization of the Human Mastoid Air Cell System © 2015 Olivier Cros Department of Biomedical EngineeringLinköping University, Sweden ISBN 978-91-7685-941-4 ISSN 0280-7971 LIU-TEK-LIC-1975:N AbstractFrom an engineering background, it is often believed that the human anatomy has already been fully described. Radiology has greatly contributed to understand the inside of the human body without surgical intervention. Despite great advances in clinical CT scanning, image quality is still related to a limited amount X-ray exposure for the patient safety. This limitation prevents fine anatomical structures to be visible and, more importantly, to be detected. Where such modality is of great advantage for screening patients, extracting parameters like surface area and volume implies the bone structure to be large enough in relation to the scan resolution.The mastoid, located in the temporal bone, houses an air cell system whose cells have a variation in size that can go far below current conventional clinical CT scanner resolution. Therefore, the mastoid air cell system is only partially represented on a CT scan. Any statistical analysis will be biased towards air cells of smaller size. To allow a complete representation of the mastoid air cell system, a micro-CT scanner is more adequate. Micro-CT scanning uses approximately the same amount of X-rays but for a much longer exposure time compared to what is normally allowed for patients. Human temporal bone specimens are therefore necessary when using such scanning method. Where the conventional clinical CT scanner lacks level of minutes details, micro-CT scanning provides an overwhelming amount of fine details.Prior to any image analysis of medical data, visualization of the data is often needed to learn how to extract the structures of interest for further processing. Visualization of micro-CT scans is of no exception. Due to the high resolution nature of the data, visualization of such data not only requires modern and powerful computers, but also necessitates a tremendous amount of time to adjust the hiding of irrelevant structures, to find the correct orientation, while emphasising the structure of interest. Once the quality of the data has been assessed, and a strategy for the image processing has been decided, the image processing can start, to in turn extract metrics such as the surface area or volume and draw statistics from it. The temporal bone being one of the most complex in the human body, visualization of micro-CT scanning of this bone awakens the curiosity of the experimenter, especially with the correct visualization settings.This thesis first presents a statistical analysis determining the surface area to volume ratio of the mastoid air cell system of human temporal bone, from micro-CT scanning using methods previously appl...

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How I Do It: Managing Radiation Dose in CT

Cited by 167 publications

References 66 publications

Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study

Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study

Facing Radiologists' Reluctance of a Degraded although Diagnostic Image Quality of Low/Ultra-low-dose CT: Our Experience

Image Analysis and Visualization of the Human Mastoid Air Cell System

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