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.

An evaluation of computed tomography dose index measurements using a pencil ionisation chamber and small detectors.

The aim of this study was to compare the values of the computed tomography dose index 100 (CTDI) obtained using two small detectors (i.e. a small ionisation chamber and a small solid state detector) with those obtained from a 100 mm pencil ionisation chamber for various input CT parameters: beam width, kVp, mAs, pitch, and head-body phantom variation.

A SIMPLIFIED METHOD FOR THE WATER-EQUIVALENT DIAMETER CALCULATION TO ESTIMATE PATIENT DOSE IN CT EXAMINATIONS.

We proposed and evaluated a water-equivalent diameter calculation without using a region of interest (ROI), (Dw,t) and compared it with the results of using a ROI fitted to the patient border (Dw,f). Evaluations were carried out on thoracic and head CT images. We found that the difference between Dw,t and Dw,f was within 5% for all images in the head region, and most images were within 5% (27 of the 30 patients, 90%) in the thoracic region.

A SIMPLE METHOD FOR CALIBRATING PIXEL VALUES OF THE CT LOCALIZER RADIOGRAPH FOR CALCULATING WATER-EQUIVALENT DIAMETER AND SIZE-SPECIFIC DOSE ESTIMATE.

The purpose of this study is to establish the relationship between the pixel value (I) of the CT localizer radiograph and water-equivalent thickness (tw) in a straightforward procedure. We used a body CTDI phantom, which was scanned in the AP and LAT projections. After transformation from the pixel values of the images to tw, water-equivalent diameter (Dw) and size-specific dose estimate were calculated on an anthropomorphic phantom and 30 patients retrospectively.

THE SIZE-SPECIFIC DOSE ESTIMATE (SSDE) FOR TRUNCATED COMPUTED TOMOGRAPHY IMAGES.

The purpose of this study is to investigate truncated axial computed tomography (CT) images in the clinical environment and to produce correction factors for abdomen, thoracic and head regions based on clinical data, in order to accurately predict the water-equivalent diameter (DW) and size-specific dose estimate (SSDE). We investigated axial images of 75 patients who underwent CT examinations. Truncated axial images were characterized by the truncation percentage (TP).

The impact of patient table on size-specific dose estimate (SSDE).

The use of parameters water equivalent diameter (D ) and size-specific dose estimate (SSDE) are becoming increasingly established as a recognised method to relate patient dose from a CT examination to the dose indicator volume CT dose index (CTDI). However, the role of the attenuation due to the patient table in these estimations requires careful consideration and is the subject of this study. The aim of this study is to investigate the impact of a minimal part of the patient table when calculating the D and SSDE.

Automated Calculation of Water-equivalent Diameter (DW) Based on AAPM Task Group 220.

The purpose of this study is to accurately and effectively automate the calculation of the water-equivalent diameter (DW) from 3D CT images for estimating the size-specific dose. DW is the metric that characterizes the patient size and attenuation. In this study, DW was calculated for standard CTDI phantoms and patient images.