Gifu University of Medical Science

About: Gifu University of Medical Science is a education organization based out in Gifu City, Japan. It is known for research contribution in the topics: Imaging phantom & Motion sickness. The organization has 89 authors who have published 202 publications receiving 1350 citations.

Examination of quality control guidelines for digital breast tomosynthesis systems in Japan

Abstract: The use of mammography equipment attached to a digital breast tomosynthesis (DBT) system is widespread in Japan. Tomosynthesis exposes the breast to X-rays continuously (or in pulses) at different angles in a single scan, yielding multiple projection images. Arbitrary multi-slice images can be reconstructed from the projection images after scanning. However, DBT increases the exposure dose compared to mammography. Therefore, it is necessary to rapidly establish performance evaluation procedures and quality control procedures for DBT. In this study, we conduct quality control measurements on DBT systems sold in Japan by five different companies and examine feasible common items. The purpose of the study was to establish a quality control method for DBT systems in Japan. The measurements were performed based on the EUREF breast tomosynthesis quality control protocol version 1.03. In this study, we attempted to measure 18 items in DBT systems. We examined whether the 18 items could be measured using each system; however, this was not an evaluation of equipment performance based on the measured values. There were some quality control items that were difficult to complete due to the specifications of a DBT system, such as equipment that required pressure during DBT operation, problems due to the shape of the bucky, and equipment that did not have stationary mode. There were also problems related to the availability of measurement data, such as with equipment that could not retrieve projection data and reconstructed data. This study clarified points to be considered for establishing common quality control items. In the future, we will carefully refer to the recently published IEC 61223-3-6, consider international harmonization, and establish DBT guidelines customized for the Japanese market.

[Quantitative Evaluation of Coincidence between Quantified Light Field Width and X-ray Field Width as Mechanical Quality Assurance].

Abstract: Aim The aim of this work was to evaluate the coincidence between light and X-ray field width in air. Background Light fields are often used for confirmation of irradiation position to superficial tumors and final confirmation of the patient's irradiation position. To guarantee collation by the light field, the light and X-ray fields must coincide. Currently, the light field width is determined mainly by visual evaluation using manual methods, such as use of graph paper and rulers. The light field width is difficult to visually recognize a definite position at the edge of the light field. Materials and methods We quantified the width of light fields emitted from a linear accelerator using a light probe detector and compared the results with those of X-ray fields. In-air measurements were conducted at the same position in the light field with the light probe detector and X-ray field using an ionization chamber installed in an emptied three-dimensional water phantom. Results The radiation field in air was approximately 2 mm larger than the light field, and we found some influence of transmission and scattered rays on the penumbra region. Before and after exchanging crosshair sheets, the fields also exhibited differences in uniformity. Conclusions The proposed method quantifies the light field using a photodetector and can be used to compare the light field with the X-ray field, conforming a useful tool for evaluating the accuracy of treatment devices in an objective and systematic manner.

A robust conversion method of radioactivities between plastic and NaI scintillation well counters for long-term quality control and quality assurance.

Abstract: Purpose The purpose of this study is to specify a simple procedure for a robust data conversion of radioactivity value between plastic scintillator (PL) and NaI scintillator (NaI) devices.