JPH019533Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is a computerized tomography device (hereinafter referred to as
(abbreviated as CT device).

In a CT apparatus, it is necessary to collect data while moving an X-ray tube and an X-ray detector to scan a predetermined tomographic plane of a patient with an X-ray beam. By the way, if mechanical or electrical noise occurs during scanning to collect this data and this noise mixes into the X-ray detector and its output signal system, the collected data will contain noise. , which adversely affects the final image and causes deterioration of the density resolution of the image.

In view of the above, the purpose of this invention is to provide an improved CT apparatus that reduces noise and improves image density resolution.

An embodiment of the present invention will be described below with reference to the drawings. The figure shows an example in which this invention is applied to a so-called third generation CT device in which an X-ray tube and an X-ray detector are integrated and rotate around an object to collect data. In this figure, a rotating frame 10 is rotatably held so that it can rotate around the subject 1, and a rotating anode X-ray tube 11 and an X-ray detector 12 are attached to this frame 10 so as to sandwich the subject 1. There is. Furthermore, the frame 10 includes a rotating anode control device 13 for controlling the rotating anode of the X-ray tube 11;
A cooling device 14 for the X-ray tube 11, an electronic circuit 15 including a preamplifier for pre-amplifying the output of the X-ray detector 12, and a fan device 16 for cooling the electronic circuit 15 are attached. This frame 10 is rotated by a drive device 17 consisting of a motor, gears, etc.
This drive device 17 is controlled by a scanning control device 18. The rotational position of the frame 10 is detected by a position detection device including a shaft encoder 19, a counter 20, and the like.

The X-ray tube drive device 22 operates under the command of the computer 21, and X-rays are emitted from the X-ray tube 11, and are transmitted to the drive device 17 via the scanning control device 18.
is activated, the rotating frame 10 rotates, and scanning with the X-ray beam is performed. During this scanning, the X-ray detector 1
The output obtained from 2 is sent to a computer 21 via an electronic circuit 15, where data is collected and a scanning position signal is sent from the counter 20 to the computer 21. In this manner, when the frame 10 rotates once, all necessary data can be collected, and image reconstruction operations such as convolution and back projection are performed by the computer 21 to reconstruct a tomographic image.

Electric power is supplied to the rotating anode control device 13, the cooling device 14, and the fan device 16 from an AC power source 23 via a relay 24. This relay 24 is connected to a slider 26 from a DC power source 28,
Electricity is supplied through 27. These sliders 26 and 27 are in contact with a rotating disk 25 that rotates at an appropriate ratio as the frame 10 rotates, and this disk 25 has a conductive surface 25a and a non-conductive surface 25a.
5b is formed. The position of this non-conductive surface 25b and the ratio with the conductive surface 25a are determined by the rotating frame 1.
It is determined that the sliders 26 and 27 are in a non-conducting state only during the period when 0 is rotating and scanning to collect data.

Therefore, before data collection, the sliders 26 and 27 are in a conductive state, and therefore the relay 24 is in a state of conduction.
Turns on, rotating anode control device 13, cooling device 14
Electric power is sent to the fan device 16 and the fan device 16 to operate them, but during the scanning period for data collection, the sliders 26 and 27 become non-conductive and the relay 24 is turned off. Therefore, during the scanning period for data collection, the rotating anode control device 13, cooling device 14, and fan device 16 stop operating, and as a result, electrical or mechanical noise may be generated from these devices during the data collection period. There is no.
Therefore, noise mixed into data taken into the computer 21 can be significantly reduced. During this data collection period, the rotating anode control device 1
3 becomes inactive due to its power being cut off, but X
Since the rotating anode of the wire tube 11 continues to rotate due to inertia,
There is no problem with radiation.

In the above embodiment, the relay 24 is controlled by the rotary disk 25 and the sliders 26, 27, but the data is transmitted by a scanning position signal from a position detection device consisting of a shaft encoder 19, a counter 20, etc. The relay 24 may be controlled by detecting the scanning period for sampling. In addition, in the above embodiment, the three devices that are noise generation sources are stopped during the scanning period for data collection, but other devices such as the photocoupler device for checking the imaging area are stopped during the data collection period. It may be configured to turn off equipment that does not need to be operated and is a source of noise.

As described above in the embodiments, according to this invention, equipment that generates mechanical and electrical noise is stopped during the scanning period for data collection, so noise can be suppressed to the absolute minimum. This makes it possible to prevent deterioration of the finally reconstructed tomographic image due to noise and improve density resolution.

[Brief explanation of drawings]

The figure is a block diagram of one embodiment of this invention. 1...Subject, 10...Rotating frame, 11...
...Rotating anode X-ray tube, 12...X-ray detector, 13...
...Rotating anode control device, 14...Cooling device, 15...
...Electronic circuit, 16...Fan device, 17...Drive device, 18...Scanning control device, 19...Shaft encoder, 20...Counter, 21...Computer, 22...X-ray tube drive device, 24... ...Relay, 25a...Conductive surface, 25b...Non-conductive surface, 2
6,27...Slider.

Claims (1)

[Scope of utility model registration request] A rotating anode X-ray tube, a cooling device for this X-ray tube,
a rotating anode control device, a drive device for the X-ray tube,
an X-ray detector, an electronic circuit into which the output of the X-ray detector is input, a fan device for cooling the electronic circuit, and an
a scanning mechanism that scans the ray beam; a scanning control device that controls the scanning mechanism; a position detection device that detects the scanning position of the X-ray beam; A computerized tomography apparatus configured to output data from a circuit and perform image reconstruction calculations using this data and the scanning position signal to reconstruct a tomographic image, which includes at least the X-ray tube cooling device and the rotating anode control device. A switch is inserted into the power supply line that supplies power to the device and the fan device, and the switch is opened during scanning for data acquisition to
A computerized tomography apparatus characterized in that power is not supplied to a wire tube cooling device, a rotating anode control device, and a fan device.