2020年5月15日
Technological development of an ultrasonic CT system that does not use X-rays - Basic research of image acquisition-
The 119th Scientific Meeting of the Japan Society of Medical Physics
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- 主催者
- 第119回日本医学物理学会学術大会
- 開催地
- Japan Yokohama WEB
[Purpose]
One of the major concerns associated with the use of CT is the associated increased radiation exposure. On the other hand, the ultrasonography is one of the safe inspection methods in terms of the exposure. However, artifacts caused by air or bone in the ultrasonography often distort these images. In this study, we have considered the possibility of usefulness by reducing the artifacts with reconstructing the multiple ultrasonic images from different angles. We report the technical concept and primary study to develop the ultrasonic CT system without the use of X-rays.
[Methods]
The ultrasonic device used was F37 (Hitachi Aloka Medical). The probe was a linear type (15MHz). The phantom was an Aquaflex gel pad (50mm x 50mm x 20mm, acoustic impedance: 2.09 x 106kg / m2s, Parker Laboratories, Inc.) used for ultrasonic examination. (1) A cylindrical hole with a diameter of 9 mm was made in the center of the phantom to create an air layer (acoustic impedance: 0.0004 x 106kg /m2s). (2) A cylindrical Teflon material (acoustic impedance: 5.28 x 106kg/m2s) with a diameter of 6.3 mm was inserted in the center of the phantom. Ultrasound images of these two phantoms are acquired from four orthogonal directions, and image processing software (GIMP: GNU Image Manipulation Program) is used to change the transparency of each image.
[Results]
If there is a material with different acoustic impedance from the phantom in the ultrasonic image from one direction, an artifact will be generated, and the artifact part cannot be displayed due to the effect. However, by acquiring images from four orthogonal directions and superimposing them into one image, it was interpolated, and one part of the display became possible.
[Conclusion]
Artifacts of ultrasound images can be reduced by acquiring four orthogonal directions. The acquisition of images from multiple directions suggested the possibility of technological development of an ultrasonic CT system.
One of the major concerns associated with the use of CT is the associated increased radiation exposure. On the other hand, the ultrasonography is one of the safe inspection methods in terms of the exposure. However, artifacts caused by air or bone in the ultrasonography often distort these images. In this study, we have considered the possibility of usefulness by reducing the artifacts with reconstructing the multiple ultrasonic images from different angles. We report the technical concept and primary study to develop the ultrasonic CT system without the use of X-rays.
[Methods]
The ultrasonic device used was F37 (Hitachi Aloka Medical). The probe was a linear type (15MHz). The phantom was an Aquaflex gel pad (50mm x 50mm x 20mm, acoustic impedance: 2.09 x 106kg / m2s, Parker Laboratories, Inc.) used for ultrasonic examination. (1) A cylindrical hole with a diameter of 9 mm was made in the center of the phantom to create an air layer (acoustic impedance: 0.0004 x 106kg /m2s). (2) A cylindrical Teflon material (acoustic impedance: 5.28 x 106kg/m2s) with a diameter of 6.3 mm was inserted in the center of the phantom. Ultrasound images of these two phantoms are acquired from four orthogonal directions, and image processing software (GIMP: GNU Image Manipulation Program) is used to change the transparency of each image.
[Results]
If there is a material with different acoustic impedance from the phantom in the ultrasonic image from one direction, an artifact will be generated, and the artifact part cannot be displayed due to the effect. However, by acquiring images from four orthogonal directions and superimposing them into one image, it was interpolated, and one part of the display became possible.
[Conclusion]
Artifacts of ultrasound images can be reduced by acquiring four orthogonal directions. The acquisition of images from multiple directions suggested the possibility of technological development of an ultrasonic CT system.