X-ray or gamma ray systems or devices – Beam control – Filter
Patent
1995-01-17
1996-10-22
Porta, David P.
X-ray or gamma ray systems or devices
Beam control
Filter
378159, A61B 603
Patent
active
055685331
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates generally to K-filters for serial high-speed rotatography and apparatus for the serial high-speed rotatography. More particularly, this invention relates to a K-filter and an apparatus for the serial high-speed rotatography which are capable of photographing radiographic images of an object speedily, accurately and with high quality from every possible angle without forming a dead angle, and hence are suitable for providing useful and detailed information to make a precision diagnosis immediately and determine a therapeutic treatment plan without delay.
BACKGROUND ART
Various photographic techniques using radiopaque or radiation-impermeable contrast media have been proposed. For instance, in the field of angiography using X-rays, the direct-film method, X-ray cinefilm method, and digital subtraction method are known.
The proposed techniques are all relied on a system in which two-dimensional serial photographing from a fixed angle is achieved with injection of an intravascular radiopaque contrast medium. Due to the fixed photographing angle, this system is in many case unable to make a correct diagnosis, e.g. of the extent and site of a coronary stricture (focus responsible for the disease) of the acute myocardial infarction based on a single run of the serial photographing, and subsequently take an appropriate therapeutic treatment, such as PTCA (Percutaneous Transluminal Coronary Angioplasty) without delay. Particularly when the object to be examined is in the dynamic state or in motion, such a fixed-position photographing is almost unable to detect the condition of a portion of the object opposite the view site.
In order to obtain correct information about the object, observation of additional images taken from many different angles is inevitable. Such a multi-angle observation, however, requires repeated photographing entailing synchronous repeated injection of the contrast medium with the resultant prolonged examination time and increased medical radiation exposure.
There have been proposed techniques related to the serial rotation stereography in which a stereoscope is used to observe an image as a stereograph from a desired position. The proposed techniques include special two trains of electronic circuits additionally provided to display analog images or digital subtraction images with predetermined angular phases on two display units, e.g., television monitors (see, Japanese Patent Laid-open Publications Nos. 61-159941 and 2-156778, for example).
The proposed techniques are, however, not available for the simultaneous stereoscopic observation by multiple viewers, nor avails no function thereof against the viewer having an artificial eye. Further, for a viewer who is amblyopic or has visual acuity imbalance, observation itself is complicated and might lead to a severe ocular fatigue.
The photographing technique used in the known serial rotation stereograph apparatus requires 10 sec or more for photographing each unit angle of rotation. In the case where an object to be examined is in motion, such as the left ventricle of an adult heart (though varying with the organs), a 40 cc intravascular contrast medium is forced out from the heart in a short period of time by the blood flow, so that the photographing angle per single injection of the contrast medium is limited to 30.degree. at maximum. In order to photograph the entire 360.degree., a great amount of intravascular contrast medium must be injected with the result that the object is subjected to undue load. Accordingly, the intended observation of serial or continual photographing conditions is practically impossible.
The prior technique disclosed in Japanese Patent Laid-open Publication No. 61-159941 gives no consideration to the time point when the injected contrast medium images in the object is photographed, and to the manner in which the contrast medium is injected toward a predetermined affected part. Accordingly, there is a risk of the injected contrast medium images at a predetermined portion bein
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JP, A, 61-142495 (Yokogawa Medical Systems, Ltd.) Jun. 30, 1986 (30. Jun. 1986), Family: none (relevant to claim No. 1).
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Kumazaki Tatsuo
Yamada Hifumi
Kumazaki Tatsuo
Porta David P.
Yamanouchi Pharmaceutical Co. Ltd.
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