Development and validation of the effective CNR analysis method for evaluating the contrast resolution of CT images.

Contrast resolution is an important index for evaluating the signal detectability of computed tomographic (CT) images. Recently, various noise reduction algorithms, such as iterative reconstruction (IR) and deep learning reconstruction (DLR), have been proposed to reduce the image noise in CT images. However, these algorithms cause changes in the image noise texture and blurred image signals in CT images.

Current situations and discussions in Japan in relation to the new occupational equivalent dose limit for the lens of the eye.

Since the International Commission on Radiological Protection recommended reducing the occupational equivalent dose limit for the lens of the eye in 2011, there have been extensive discussions in various countries. This paper reviews the current situation in radiation protection of the ocular lens and the discussions on the potential impact of the new lens dose limit in Japan. Topics include historical changes to the lens dose limit, the current situation with occupational lens exposures (e.

Arterial contour detectability in head CT angiography.

Purpose: Arterial contour extraction is essential for visualization and analysis of vasculature in CT angiography (CTA). A means for evaluating the detectability of artery contours CTA images is required. We developed and tested a new method for this purpose based on phase information from two-dimensional Fourier transforms of CTA images.

A new automated assessment method for contrast-detail images by applying support vector machine and its robustness to nonlinear image processing.

The automated contrast-detail (C-D) analysis methods developed so-far cannot be expected to work well on images processed with nonlinear methods, such as noise reduction methods. Therefore, we have devised a new automated C-D analysis method by applying support vector machine (SVM), and tested for its robustness to nonlinear image processing. We acquired the CDRAD (a commercially available C-D test object) images at a tube voltage of 120 kV and a milliampere-second product (mAs) of 0.

Organ dose and effective dose estimation in paediatric chest radiographic examinations by using pin silicon photodiode dosemeters.

Organ and effective doses during paediatric chest radiographic examination were investigated for various tube voltages between 60 and 110 kV at a constant milliampere-second value and focus-to-film distance by using an in-phantom dose measuring system and a Monte Carlo (MC) simulation software (PCXMC), where the former was composed of 32 photodiode dosemeters embedded in various tissue and organ sites within a 6-y-old child anthropomorphic phantom. Lung doses obtained ranged from 0.010 to 0.

Comparison of radiation doses between newborns and 6-y-old children undergoing head, chest and abdominal CT examinations: a phantom study.

Radiation doses in paediatric computed tomography (CT) were investigated for various types of recent CT scanners with newborn and 6-y-old phantoms in which silicon-photodiode dosemeters were implanted at various organ positions. In the head, chest and abdominal CT for the newborn phantom, doses for organs within the scan region were 21-40, 3-8 and 3-12 mGy, respectively. The corresponding doses for the child phantom were 20-37, 2-11 and 4-17 mGy, respectively.

Patient radiation dose in prospectively gated axial CT coronary angiography and retrospectively gated helical technique with a 320-detector row CT scanner.

Purpose: The aim of this study was to evaluate radiation dose to patients undergoing computed tomography coronary angiography (CTCA) for prospectively gated axial (PGA) technique and retrospectively gated helical (RGH) technique.

Methods: Radiation doses were measured for a 320-detector row CT scanner (Toshiba Aquilion ONE) using small sized silicon-photodiode dosimeters, which were implanted at various tissue and organ positions within an anthropomorphic phantom for a standard Japanese adult male. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed according to guidelines published in the International Commission on Radiological Protection Publication 103.

Radiation dose evaluation in tomosynthesis and C-arm cone-beam CT examinations with an anthropomorphic phantom.

Purpose: The objective of this study was to evaluate organ dose and the effective dose to patients undergoing tomosynthesis (TS) and C-arm cone-beam computed tomography (CBCT) examinations and to compare the doses to those in multidetector CT (MDCT) scans.

Methods: Patient doses were measured with small sized silicon-photodiode dosimeters, 48 in number, which were implanted at various tissue and organ positions within an anthropomorphic phantom. Output signals from photodiode dosimeters were read out on a personal computer, from which organ and effective doses were computed.

Radiation dose evaluation in head and neck MDCT examinations with a 6-year-old child anthropomorphic phantom.

Background: CT examinations of the head and neck are the most commonly performed CT studies in children, raising concern about radiation dose and their risks to children.

Objective: The purpose of this study was to clarify radiation dose levels for children of 6 years of age undergoing head and neck multidetector CT (MDCT) examinations.

Materials And Methods: Radiation doses were measured with small-sized silicon-photodiode dosimeters that were implanted at various tissue and organ positions within a standard 6-year-old anthropomorphic phantom.

Evaluation of radiation doses from MDCT-imaging in otolaryngology.

The purpose of this study was to clarify patient doses in the current otolaryngological multi-detector row computed tomography (MDCT) examinations. Patient doses were measured with an in-phantom dosimetry system which was composed of 48 photodiode dosimeters embedded within an anthropomorphic phantom. Organ and effective doses were evaluated according to the International Commission on Radiological Protection Publication 103.