The automated measurement of CT number linearity using an ACR accreditation phantom.

We developed a software to automatically measure the linearity between the CT numbers and densities of objects using an ACR 464 CT phantom, and investigated the CT number linearity of 16 different CT scanners. The software included a segmentation-rotation method. After segmenting five objects within the phantom image, the software computed the mean CT number of each object and plotted a graph between the CT numbers and densities of the objects.

Impact of ROI Size on the Accuracy of Noise Measurement in CT on Computational and ACR Phantoms.

Background: The effect of region of interest (ROI) size variation on producing accurate noise levels is not yet studied.

Objective: This study aimed to evaluate the influence of ROI sizes on the accuracy of noise measurement in computed tomography (CT) by using images of a computational and American College of Radiology (ACR) phantoms.

Material And Methods: In this experimental study, two phantoms were used, including computational and ACR phantoms.

Comparative estimation of pleural effusion volume based on lateral decubitus position of chest x-ray and CT scan imaging.

Previous study using thoracic phantom for estimating fluid volume has been obtained which represents the case of pleural effusion based on the size of the x-ray radiograph. The models are obtained in the form of three equations, the pleural effusion volume as a function of height, length times the height, and area of the radiograph image. The three models of estimation have high linearity with ratio value more than 0.

An Improved Method of Automated Noise Measurement System in CT Images.

Background: It is necessary to have an automated noise measurement system working accurately to optimize dose in computerized tomography (CT) examinations.

Objective: This study aims to develop an algorithm to automate noise measurement that can be implemented in CT images of all body regions.

Materials And Methods: In this retrospective study, our automated noise measurement method consists of three steps as follows: the first is segmenting the image of the patient.

Characteristics of laser induced breakdown investigated by a compact, nongated optical multichannel analyzer system and its potential application.

Laser induced breakdown is a highly temporally and spatially dynamic phenomenon, normally studied using a highly temporally resolved optical detector system. In this work, a compact, low cost optical multichannel analyzer (OMA) system without a built-in temporal gating device and thus operated under a free running mode was used to investigate the characteristics of laser induced plasma. A Nd-YAG laser beam was used as the excitation source from several samples, namely, copper, zinc, and aluminum plates.