JPS5939879B2 - X-ray diagnostic equipment operated by computer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray diagnostic apparatus designed to prevent overloading of an X-ray tube.

Computerized tomography is one of the X-ray diagnostic equipment.
There is a computer-operated X-ray tomography device called a CT device (hereinafter abbreviated as CT device).

This CT device moves an X-ray tube and an X-ray detector facing each other along the tomographic plane of the subject in the same direction and at the same speed, and each time they move, the angle with respect to the tomographic plane changes. This is repeated again, and thereafter the angle is sequentially changed to collect data on the X-ray absorption rate for various angles of the tomographic plane of the subject.

After collecting sufficient data, this data is analyzed by a computer, the X-ray absorption rate of each position on the tomographic plane is calculated, and the tomographic plane is reconstructed with a gradation level corresponding to the absorption rate. With this system, the composition of each part of the tomographic plane can be analyzed in as many as 2,000 gradations, making it possible to obtain clear tomographic images of everything from soft tissue to hard tissue. By the way, in such a CT device, data on X-ray absorption rate is collected while continuously emitting pulsed X-rays, and the exposure period of the pulsed X-rays is extended over an extended period of time. It lasts for several minutes.

Therefore, the X-ray tube will be heated for several minutes. In other words, an X-ray tube emits X-rays by heating a filament to emit thermoelectrons, which collide with a point on an anode (this point of collision is called a focal point). The temperature rises due to heat generation due to the collision of thermoelectrons.

Therefore, if X-rays are continuously emitted, the material will eventually dissolve. The allowable limit immediately before melting is the maximum allowable capacity of the X-ray tube, and it is necessary to use the tube within this capacity. Generally, the tube voltage applied to an X-ray tube,
Since the temperature rise is determined by three factors: the tube current and the energization time, the anode heat capacity and heat unit (Heat-Unit (hereinafter referred to as H-U)) are calculated by multiplying these three factors.
A unit system called ``H-U'' is defined, and the capacity of the X-ray tube is expressed by this H-U value.

Therefore, for example, for an X-ray tube with a capacity of 500 CH-U, the product of the applied tube voltage, tube current, and application time is 5.
00CH-U] or less. In general, diagnostic X-ray equipment uses a single irradiation method, and after one irradiation, there is a considerable pause period, so it is not dependent on the overall allowable heat capacity of the X-ray tube anode, and the instantaneous A method has been adopted in which the maximum load capacity for short-term use, which is limited by the surface temperature that rises, is determined and the load on the X-ray tube does not exceed this limit.

However, like a CT machine, the exposure and cutoff are repeated,
In the case of continuous operation, the load is applied over a long period of time, and therefore the restriction from the temperature rise of the entire anode is greater than from the instantaneous rise in the surface temperature of the anode.

Therefore, a determination method based on the short-time rating of X-ray overload prevention used in general diagnostic X-ray equipment (determining whether the X-ray tube is used within the maximum load that can withstand one exposure) ), when repeated X-ray exposure is performed,
As the number of repetitions increases, the temperature of the entire anode increases, and although there should be sufficient margin in the short-time rating, in reality the temperature of the entire anode is increasing, and the surface temperature of the anode suddenly becomes extremely high. There is a great danger that the X-ray tube will be destroyed by rising, and it is impossible to prevent the X-ray tube from being overloaded. By the way, the temperature rise of the anode due to X-ray exposure from an X-ray tube depends on the applied tube voltage, tube current, and exposure time.
Once the U value is determined, the temperature equivalent to the temperature of the anode of the X-ray tube, which is cooled down during the radiation suspension period, can also be given as the H-U value. Therefore, the H-U values applied to the X-ray tube are integrated, and this integrated H-
H- equivalent to the temperature drop due to cooling during the rest period from the U value
Subtract the U value (this can be ignored if there is almost no rest period) to find out the actual H-U value corresponding to the current X-ray tube anode temperature, and this actual H-U value is the allowable value for the entire anode. If the shear is cut off when the H-U value of the maximum load capacity (long-term rating) determined by temperature is reached, overload of the X-ray tube can be prevented. The present invention was made in view of the above circumstances, and it integrates the H-U value added to the X-ray tube, and subtracts the integrated H-U value from the H-U value of the maximum load capacity due to long-term rating. Computer-operated X-ray diagnostics that can prevent overloads by determining the residual H-U value that can be applied and detecting whether or not an overload condition has occurred. The purpose is to provide equipment. An embodiment of the present invention will be described below with reference to the drawings. In the figure, 1
sets the tube voltage and tube current to be applied to the X-ray tube XT, their application time, etc., and generates a control output according to the set conditions every time an X-ray exposure command is given, and the rotation load prevention device 1
2 is a calculation circuit that calculates the H-U value by multiplying the three types of setting control outputs output by the X-ray controller 1; 3 is a CT device (not shown); This is a signal generation circuit that commands the number of pulsed X-ray irradiations required to collect data per cross section, outputs an irradiation command every time one X-ray irradiation is completed, and operates until a predetermined number of irradiations is reached. 4 responds to the command signal from the signal generating circuit 3 and generates the calculation circuit 2.
5 is an integration circuit that calculates the integrated value of the H-U value given to the X-ray tube XT by integrating the calculated values of A load capacity setting circuit 6 receives output signals from the load capacity setting circuit 5, the aforementioned X-ray exposure number command signal generation circuit 3, and the integration circuit 4, and determines the allowable load of the X-ray tube at the time of exposure. 7 is an arithmetic circuit that receives output signals from the integration circuit 4 and the detection circuit 6 and performs arithmetic operations to generate an output signal; 8 is an output signal from the arithmetic circuit 7; 9 is a display circuit for receiving the output signal from the determining circuit 8 and displaying it.

Next, the operation of this device having the above configuration will be described.

The X-ray tube XT receives a command signal from the exposure number command signal generation circuit 4 and emits X-rays under the conditions set in the X-ray controller 1. The X-ray exposure number command signal generation circuit 3 is activated upon receiving an exposure start signal from the CT apparatus, and outputs a command signal for the number of exposures. At the same time, the X-ray controller 1 sets the set tube voltage,
A control output for the tube current and application time is output, and a signal of this setting condition is given to the X-ray tube XT in synchronization with the command signal to perform X-ray exposure. At that time, these control outputs are calculated by the calculation circuit 2.
This calculation circuit 2 multiplies the set condition value of the X-ray controller 1 to calculate the heat unit value to be applied to the X-ray tube XT. This calculated value is added to the integration circuit 4, which integrates the heat unit value applied each time it receives the command signal from the irradiation number command signal generation circuit 3. This integrated value is sent to the arithmetic circuit 7. One side detection circuit 6
receives the output signal from the load capacity setting circuit 5, the output signal from the X-ray exposure number command signal generation circuit 3, and the output signal from the integration circuit 4, and determines the allowable load of the X-ray tube at the time of exposure (first exposure time). At the time of injection, the output signal (equivalent to the output signal from the load capacitance setting circuit) is detected and an output signal is generated. Here, the arithmetic circuit 7 receives the output signal from the integration circuit 4 and the output signal from the detection circuit 6, performs arithmetic operations, and calculates the residual H-U value that the X-ray tube XT can provide. The load determination circuit 8 receives the output signal from the arithmetic circuit 7, determines whether or not subsequent X-ray exposure is possible, and generates an output signal. If this output signal is a negative signal, the overload prevention circuit 12D operates and X-ray exposure is stopped. Therefore, if X-ray exposure is cut off at the point where the residual H-U value calculated by the arithmetic circuit 7 becomes zero, the safety of the examinee or operator is maintained and overload of the X-ray tube XT is prevented. and can be protected. In this way, H-U added to the X-ray tube
At the same time, the accumulated HU value is subtracted from the HU value of the maximum load capacity according to the X-ray tube's rating to find the residual HU value that can be applied to the X-ray tube, and this is removed. This X-ray diagnosis has excellent features such as overload can be effectively prevented, ensuring the safety of the examinee and operator, and preventing the X-ray tube from breaking. equipment can be provided.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. By subtracting and correcting the HU corresponding to the temperature, a more accurate residual HU value can be obtained.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. 1...1...X-ray controller, 2......calculation circuit,
3... X-ray exposure number command signal generation circuit, 4...
...Integrator circuit, 5...Load capacity setting circuit,
6...Detection circuit, 7...Arithmetic circuit, 8
. . . Load judgment circuit, 10 . . . X-ray exposure permissibility judgment circuit.

Claims (1)

[Scope of Claims] 1. An X-ray controller that sets X-ray exposure conditions, and an X-ray exposure frequency command that generates a signal that instructs the number of X-ray exposures based on the settings of the X-ray controller. A computer operated computer comprising: a signal generation circuit; and an X-ray exposure permissibility determination circuit that receives signals from the X-ray controller and the X-ray exposure frequency command signal generation circuit and determines an exposure permissible state of the X-ray tube. X-ray diagnostic equipment. 2. The apparatus according to claim 1, wherein the X-ray exposure permissibility determination circuit includes a circuit that receives an output signal from the X-ray controller and calculates a heat unit value to be applied to the X-ray tube; A circuit that integrates a heat unit value for each X-ray exposure, a circuit that sets a heat unit value of an allowable load capacity of the X-ray tube, the load capacity setting circuit, and an X-ray exposure frequency command signal generation circuit. and a detection circuit that receives the output signal from the integration circuit, detects the permissible load of the X-ray tube at the time of irradiation, and generates an output signal; The X-ray tube is provided with an arithmetic circuit that generates an output signal, and a load determination circuit that receives an output signal from the arithmetic circuit, determines an allowable load, and generates an output signal, thereby preventing overload on the X-ray tube. A computer-operated X-ray diagnostic device characterized by: