Toshio Yoshida

An accurate calibration method of ultrasound images by center positions of a metal ball

This paper provides a novel method for three-dimensional tracking of ultrasound images. One of the issues to determine the position of a ultrasound image plane is the thickness of the image plane. The proposed methodology address the issue by the calibration phantom using a fiducial sphere with the diameter of 5.5 mm because comet-trail artifact can be observed in the image plane through the center of the sphere. Meanwhile, to measure the sphere center accurately by a tracking device, a pointer tool with the same sphere at the tip is also proposed. To validate the feasibility of the method, simulation and phantom tests were conducted. From the results of the phantom test, the accuracy of the calibration was 0.65, 0.40, and 0.42 mm in 10, 50, 100 points calibration. The results demonstrate that the proposed method has a great potential for accurate US probe calibration.

Image plane positioning by pneumatic actuators for ultrasound guidance

Image guided procedures such as percutaneous needle insertion or high intensity focused ultrasound, have become quite widespread. In images acquisition, ultrasound (US) is convenient to use in a conventional operating room, and inexpensive compared to CT and MRI. However, US requires to handle an US probe and do not have the base coordinate system. Therefore, intraoperative image position is unclear and cannot position to interested area. To address the issues, we have developed a robotic system based on US calibration and a probe scanning robot. In this study, to validate the implement system, positioning accuracy of an image plane was evaluated. Moreover, we developed an automated US guidance system with a conventional US probe. The system enables image plane positioning to visualize a therapeutic tool automatically. From the results, positioning accuracy of the image plane was 1.6 mm and 1.5 deg, maximally. In the phantom test, the error between the positions of the image plane and the mock needle was 2.5 mm and 0.9 deg. We have confirmed that the proposed system is greatly applicable for an intraoperative US guidance.

Isolation and X-ray crystal structure of mintsulphide, a novel sulphur-containing sesquiterpene

A sulphur-containing sesquiterpene, mintsulphide, was isolated from peppermint oil and its structure was determined by X-ray crystallographic analysis.

Isomerization and Racemization of Menthols Part III

The hitherto unknown cyanoacetates of menthol isomers, i.e., (±)-menthyl, (±)- and (+)-neomenthyl, and (±)- and (+)-isomenthyl cyanoacetate, have been prepared. It has been proved to be possible to isolate effectively pure (±)-menthol from optically inactive mixture of isomers through the cyanoacetate, followed by saponification.

A New Synthetic Method of Methyl Ketones Part III:Syntheses of cis - and trans -Jasmone

A simple and stereospecific method has been developed for the synthesis of cis-jasmone. 3-Methyl-2-cyclopentenone (V) was condensed with cis-2-pentenyl chloride, which was prepared from propargyl alcohol, by means of sodium amide in liquid ammonia to yield stereochemically pure cis-jasmone (VIb) in 39~40% yield. By the similar direct alkylation, trans-jasmone (VIc) and dihydrojasmone (VIa) were also synthesized in moderate yields.

Preparation and Derivatives of Optically Inactive Isopulegols

The unknown three isomers of optically inactive isopulegol, (±)-isopulegol(II), (±)-neo-isopulegol(III), and (±)-iso-isopulegol(IV) were isolated; then 3,5-dinitrobenzoates and p-nitrobenzoates were prepared from them.