To begin with, tell us about the principles behind the digital radiography system incorporating the LANMIT (Large Area New MIS Sensor and TFT) X-ray imaging sensor.
- Watanabe
- First, X-rays pass through the body and are then absorbed by the phosphor layer on the top of the imaging panel. The phosphor layer converts X-rays into visible lights based on their strength, which varies depending on the conditions inside the body. Images are then formed by transforming invisible X-rays into visible lights.
This is the same principle behind analog X-rays using film, isn't it?
- Watanabe
- Yes. The difference between digital and analog becomes apparent after this. Instead of film, the visible lights are received by an optical sensor made up of an amorphous silicon layer. Depending on the lights, electrons are generated and are transferd to an image processing circuit by controlling the switching elements (TFT).
Structure of the Digital Radiography System
Cross-Section of the Digital Radiography System
A single signal is produced for each electron emitted by light. Is one set equal to one pixel?
- Watanabe
- That's right. It's probably easier to understand if you think of the opposite pattern found in LCD panels, which change the alignment of the electrons flowing through the liquid crystal into visible light.
- Tamura
- Because the CXDI-50RF incorporates cesium iodide (CsI) as the phosphor layer, which offers effective X-ray absorption and high signal-to-noise performance, it is possible to obtain high-resolution images using less than half the X-ray radiation required with analog technology, and to display dynamic images on a monitor in real time.
The static imaging device incorporating LANMIT first offered support for dynamic images in 2009. What was your approach during development?
- Tamura
- Actually, we had already considered the development of dynamic imaging technology when Canon pioneered the static imaging device in 1998. However, a decision was made to concentrate on improving the performance of static imaging, so we suspended our work on dynamic imaging. It was the right decision, and the stable static images and device performance of our products have now become widely recognized. We then decided to make a device that would support dynamic imaging while retaining static image performance, which would ensure we maintained our reputation in the market.
The development concept focused on adding dynamic imaging to the existing product characteristics of still imaging and portability, while also being affordable. It was like adding a movie function to a digital camera (laughs). We imagined that the dynamic imaging function would mainly be used to determine ideal positioning when taking still images during an examination.
What kind of uses does it have?
- Takekoshi
- Barium imaging of the stomach and imaging of joints are two examples. Dynamic images can be used to find the right timing and angle to take a still image by moving the subject's body to change the angle. It can also be used in what are called "image-guided procedures," which makes use of X-ray imaging when inserting a needle into an affected area to check the position of the needle during tests.
Why were you focused on portability?
- Takekoshi
- In the past, separate devices and rooms had been used to take images with the patient standing up, lying down or where the equipment was movable. Following the release of Canon's first portable radiography system, the company has enabled reductions in costs and required installation space by allowing a variety of types of imaging to be performed using a single device. These benefits had to be maintained when adding dynamic imaging capabilities to the product.
