EP0233175A1

EP0233175A1 - Apparatus for setting the exposure parameters of an x-ray equipment

Info

Publication number: EP0233175A1
Application number: EP85900156A
Authority: EP
Inventors: Istvan Biro; Zoltan Kasa; Gyorgy Areldt; Gábor ZBOROVSZKY; György RELDT; Ferenc Vas
Original assignee: Medicor Muvek
Current assignee: Medicor Muvek
Priority date: 1984-11-21
Filing date: 1984-11-21
Publication date: 1987-08-26
Also published as: WO1986003363A1; HUT42665A; HU195383B

Abstract

Dans ce dispositif, la fonction de commande est partagée entre un bloc de commande dépendant de la machine, comprenant un microcontrôleur, et un ordinateur personnel. Le bloc de commande est conçu pour ajuster les différents réglages de l'équipement à rayons X et pour commander les conditions devant régner entre ces paramètres pour obtenir un fonctionnement fiable et réaliser une interface avec l'ordinateur personnel, celui-ci étant utilisé en mode dialogue par le personnel de radiologie pour sélectionner l'examen requis et pour régler les conditions réelles de l'examen.In this device, the control function is shared between a machine-dependent control block, comprising a microcontroller, and a personal computer. The control block is designed to adjust the various settings of the x-ray equipment and to control the conditions that must exist between these settings to obtain reliable operation and to interface with the personal computer, the latter being used in mode dialog by the radiology staff to select the required exam and to set the actual exam conditions.

Description

APPARATUS FOR SETTING THE EXPOSURE PARAMETERS OF AN X-RAY EQUIPMENT

The present invention relates to X-ray control technique, more particularly to an apparatus for setting the exposure parameters such as the high voltage, X-ray tube current and exposure time of an exposure. It is well known in the X-ray art that in case of each X-ray exposure the radiologist or the X-ray per¬ sonnel should set the parameters of exposure according to the actually require examination. The parameters which can be expressed in volt, milliamper and second/milli- second/ units can be varied in each X-ray equipment within wide ranges, and in spite of the experiences such personnel might have acquired, X-ray specialists prefer defining the examinations rather than the technical para¬ meters connected with such examinations. The high price of X-ray films and the striving of using minimum dosages to the patients impose the require¬ ment that each exposure should be made under optimum con¬ ditions. The parameters of an exposure depend largely on

the body part which should be examined, and within a body part several different examinations can be carried out. The whole range of examinations for all body parts is in

^'.^{'* '} the^'.'b.'rd'er^': of several-"h^;undreds"j ^•'and 'one^• mig t no ^;' xpect ;^••"■^• 5 from an X-ray personnel to exactly know the optimum para¬ meters for each examination. The parameters of an optimum exposure depend not only on the type of the examination but also on the patient and its conditions. Such con¬ ditions can be the age, sex, weight, etc. There are other

10 factors which exert an influence on the exposure para¬ meters which depend on the various technical conditions of the X-ray equipment and of the film. Such are e.g. the sensitivity of the film or the video system, the possible use of a bucky grid, the imaging distance, etc.

15 The setting. of the optimum parameters requires the aid of an artificial intelligence, recently of computers.

There are a number of computer-aided X-ray equipments known, in which a special-purpose computer is used as an aid for adjusting the required exposure parameters. A

20 typical example for such a control is the control unit of the P0LYD0R0S 50/80/100 generators of the Siemens Ag. /G.F.R./. In this control unit a matrix consisting of 7 rows and 7 columns is arranged in the control panel, and besides the rows there is illustrated a standing human

25 figure, and each row is associated with a body-part on the corresponding height and the columns are associated with various examinations on the given body-part.

The selection of the examination occurs by pressing the field in the crossing of the proper row and column, and

30 in response to the selection an appropriate inscription on that field will be illuminated, and a display board will indicate the parameters associated with that particular examination. In addition to the selection of an examination the control unit enables the setting of several other con-

35 ditions. This kind of control offers a great help for the X-ray personnel in adjusting the parameters of an exposure. There are, however, a number of limitations connected with

^{■ '}- -"the design- σf.-such special^purpo-se compu ers.- The-.--first,-^•■^•.-. • 5 limitation lies in the organization of the keyboard. The matrix of 7 rows and 7 columns is about the maximum that can be handled without causing confusion in the selection. There is, however, a need for a more detailed differenti¬ ation between possible examinations. This need cannot be

10 met by such design. The limitations of the size of the keyboard determine the maximum number of possible adjust¬ ments for the various conditions that must be taken into account in determining an exposure.

The control unit is closely related to the specific

15 type of the X-ray generator with which it is associated, and its use with an other or improved equipment is prac¬ tically impossible. Also, if the technical progress introduces new means or conditions that must be regarded in selecting the exposure parameters, such control units

20 cannot meet these new requirements.

There is a further problem connected with the costs. The special purpose computers owing to the more limited scale of their production are much more expensive than e. g. the general purpose computers or personal computers

25 manufactured in large scales.

The object of the present invention is to provide an apparatus for setting the exposure parameters of an X-ray equipment, that imposes no limitations regarding the number of body-parts and differentiation in the res-

30 pective body-parts to be examined and that enables the changing or widening the scale of such examinations, which is not dependent on a particular equipment, which can take into account various conditions of an examination and the changing of such conditions and which can be

35 utilized a-lso for other purposes.

OMP - . -

According to the invention it has been discovered that one must differentiate between conditions which are _.. dependent on a particular;_ X-ray_ equipment and those depen- "' dent only on the selection- of the' examination on the part -^' -^' 5 of the X-ray personnel. The first group of conditions should be satisfied by a control block including a micro¬ controller that coordinates various machine-dependent tasks, and in addition to this function it should serve as an interface towards a general purpose computer to receive the specific information defining the exposure, and the second group of conditions should be satisfied by a general purpose computer like a personal computer, which can be programmed easily to provide a dialogue-type se¬ lection of the required examination and conditions with the X-ray personnel. The sharing of the tasks of control between these two intelligent devices has a number of advantages. In the first place it should be mentioned that the personal computers are well-known for the public, their programming is comparatively easy and imposes no problems, their price is low compared to their performance and they can be used for purposes other than setting the exposure parameters, like doing the administrative work in an X-ray department or processing several X-ray equip¬ ments, etc. The special-purpose control unit is relieved from a number of complicated tasks, therefore it can be made by inexpensive components and in such a way to provide op¬ timum reliability and performance to the X-ray machine it is associated with. The apparatus according to the invention will now - be described in detail in connection with preferable embodi¬ ments thereof, in which reference will be made to the accom¬ panying drawings. In the drawing:

FIG. 1 shows the general block diagram of the appa- ratus according to the invention,

FIG. 2 shows the control block and the X-ray equip¬ ment in more detail, FIG. 3 is a flow-chart illustrating the algorythm ""^;" - '.^'•" ^''^:-"'^; .^{•' '}- of setting 'the ^"parameters ^"of an 'exposure in response to information obtained from the personal computer, FIG. 4 shows the display picture during body-part selection, FIG. 5 shows the display picture during examination selection, and

FIG. 6 shows the display picture when both selections have been made. FIG. 1 shows the overall block diagram of the X-ray control system according to the invention. The arrangement consists of three main functional blocks i.e. conventional X-ray equipment 100, control block 200 and personal com¬ puter 300. The functional blocks of the X-ray equipment 100 have been illustrated in such depth only which is sufficient for understanding the way of control. The X-ray equipment 100 has an X-ray tube^* 101 with an anode and a cathode connected via high voltage rectifier 102 to out¬ put of high voltage transformer 103. The primary coil of the transformer 103 is connected to a conventional voltage adjusting block 104 which has voltage adjustment control inputs 105 for the adjustment of the voltage of the trans¬ former 103 according to preset values determined by the control block 200.

The filament of the X-ray tube 101 is driven by fila¬ ment transformer 106 which has a primary coil supplied by chopper 107 with a voltage determined by the control block 200. The effective output voltage of the chopper 107 de¬ termines the current value of the X-ray tube 101 during exposure. The duration of exposures is determined by timer 108 coupled e.g. to control input of the voltage ad ust- ing block 104.. The timing of the timer 108 is defined by

OMPI length of a timing pulse generated by the control block 200 and coupled to the timer 108. For. otating the anode of the -•^•- X-ray-tu-be-.-lOl an anode -rotation- sta or 109- is-- used: which is driven by anode rotation control block 110 receiving rotation command signals from the control block 200.

A block of auxiliary equipments 111 is shown which symbolizes various optional and conventional equipments usable in connection .with the X-ray equipment such as bucky grid, automatic exposure control, automatic brightness control., fluoroscopy control, tomographic equipment connec¬ tion block, etc. It is common for the auxiliary equipments that their operation /or presence/ is reported to the control block 200 via port 50 and if they require control signals, such signals are supplied via port 60 from the control block 200.

The control block 200 and the personal computer 300 have the task of setting and controlling the operation of the X-ray equipment 100. This task is distributed between the personal computer 300 and the control block 200 in such a way that the personal computer 300 can provide for a high degree of flexibility and comfort in handling regard¬ ing the adjustment and setting the parameters of exposures, while the control block 200 is an intelligent interface that coordinates the various control processes and provides for the required safety in accordance with the actual structural design of the X-ray equipment 100.

The control block 200 comprises a microcontroller 210 as its main block which can be made preferably by an INTEL 8051 microprocessor. The microcontroller 210 is connected to a kV control unit 220 which is connected via port 10 to the control input of the voltage adjusting block 104, to a fila¬ ment generator 230 for controlling the chopper 107 via port 20, to an SCR controller 240 connected via port 30 to the control input of the timer 108, to an anode rotation control unit 250 connected via port 40 to the anode rotation control block 110 and to ports 50 and 60 for transmitting and receiving signals to or from the block of auxiliary equip¬ ments 111. The microcontroller 210 has a standard serial interface port 260 -for establishing a connection via a--^' - standard serial line 70 towards the personal computer 300. There is provided a port 80 of the microcontroller 210 with a standard exposition pushbutton 82. The various status data of the X-ray equipment 100 are reported to the control block 200 via connections .towards the microcontroller 210 which have not been shown in the drawing. Such connections are used for the purpose of interrupting or inhibiting the exposure if the actually set values are not conforming to those set by the control block 200.

FIG. 2 shows the functional block diagram of the control block 200 in detail. The microcontroller 210 is made preferably by a conventional microprocessor such as the type 8051 of INTEL Corporation. FIG. 2 shows a portion of the internal structure of this microprocessor used ^' operatively in the present invnetion. The microcontroller 210 comprises a serial interface 211 with an input buffer for receiving and storing serial data arriving through input data line RXD via port 260 from the personal computer 300 and for transmitting the data stored in the buffer through output data line TXD towards the personal computer 300. There is provided in the microcontroller 210 a CPU 212, a random access memory 213, a read only memory 214, first and second timers 215 and 216, respectively, and a set of ports each including a predetermined number of in¬ put/output terminals. Port 0 has eight terminals which are used for setting the kV value and the time of exposure.

Ports 1 to 3 are associated with various auxiliary functions including the connection towards the exposition push¬ button 82, the setting of the anode rotation, the connec¬ tions towards the block of auxiliary equipments 111 and to receive status information from the functional blocks of

the X-ray equipment 100.

The setting of the mA value of the X-ray equipment 1Q0 occurs by means σf the. first -timer 215 which delivers a pulse ^'train'wi^'th a frequency determined by the micro-^' controller 210. The output of the first timer 215 is coupled to a frequency to voltage converter 231 which provides a voltage output signal in response to the frequency of the input pulses. This voltage signal is coupled to control in¬ put of a voltage controlled, power supply 232 receiving a predetermined supply voltage O„ . The voltage controlled power supply 232 supplies an output voltage via port 20 to the chopper 107 in the equipment 100 which corresponds to the voltage applied to its control input. The output of the chopper 107 drives via a sensor resistor R the primary winding of the filament transformer 106. The voltage accross the resistor R is received by a current comparator 233 which turns on if the current through the resistor R drops below a predetermined treshold level. This turned on state of the comparator 233 is fed back to the microcontroller 210 to signalize that the filament current is out of normal range. The setting of the time of exposure occurs through the first output terminal 0 of port 0. When the conditions for the exposure are all met, the microcontroller 210 delivers a pulse to this terminal with a length equal to the required duration of exposure. The SCR controller 240 is in fact a buffer amplifier which provides a suitable driving pulse to the timer 108 in the X-ray equipment 100.

The kV value of the X-ray equipment is set by means of the voltage adjusting block 104. In a preferable way of settin the high voltage the high voltage transformer 103 has a pre¬ determined number of primary coils which are connected to respective outputs of contactors 112 such as shown in FIG. 2. The contactors 112 can be operated according to predetermined combinations and each combination is associated with a certain number of effective primary turns of the transformer 103_j thus a corresponding high voltage is obtained in the secondary of the transformer 103. The contactors 112 are driven by respective relays 113 which receive their drive through, port 10 from the kV control unit 220., The unit 220 consists of as many driver stages as the number of the relays 113 and it has a corresponding number of input lines. In the embodiment shown in FIG. 2 this number is seven and takes the terminals 1 to 7 of port 0. The unit 220 can be imp¬ lemented -by conventional drivers with the type ULN 2803 of SPRAGUE Corp.

The anode rotation is controlled by an output ter¬ minal of port 1 of the microcontroller 210 which turns on the anode rotation control unit 250. This unit includes a buffer amplifier and a relay which provides a voltage signal through port 40 to the anode rotation control block 110. For understanding the way of setting and control of the X-ray equipment 110 by means of the control block 200 it should be supposed that the personal computer 300 de¬ livers at least the following three information to the microcontroller 210: a/ the kV value in the form of a coded combination that defines the logical states of terminals 1 to 7 of port 0 associated with this value; b/ the mA value of the current that should flow through the X-ray tube during exposure, in the form of a frequency code which should be delivered by the first timer 215; and c/ the duration of the exposure i.e. the SCR value. These three items of information are passed through the serial line 70 to the microcontroller 210 in the form of a serial sequence.

The logic of the operation is visualized in FIG. 3 which is the flow-chart of the main events that take place during an exposure. The first decision that the CPU 212 should examine is the actual state of the serial buffer of the interface 211. If the buffer is loaded by data /first with the data of the kV code/, the process starts and the kV code is read from the buffer in port 0 /terminals 1 to 7/.^' The -next decision is ^'similar to the first one^', ^•- ^••' i.e. the CPU examines whether the serial buffer is loaded /now with the information of the mA value/. If this in¬ formation is available, the filament frequency code is written from the buffer in the first timer 215, and this timer is started to produce a pulse sequence by the predetermined frequency. This frequency is converted by the converter 231 to a voltage value which determines the attenuation ratio i.e. the output voltage of the controlled power supply 232. The chopper 107 generates a squarewave voltage signal which is passed to the filament transformer 106 and the X-ray tube will be heated.

The next step comprises a similar decision, and if the next information /the duration of the exposure/ is al¬ ready available in the buffer, the corresponding time code is written in the second timer 216. When this task has been accomplished, the CPU sets terminal r_, of port 1 in on-state, whereby the anode rotation is started. Now, a predetermined waiting tiπre_,is introduced which is the function of the time required for the rotation transients, of the filament settling time and of the time required for the setting of the con- tactors. The waiting time is somewhat longer then the longest one of these three conditions. When the waiting time has elapsed, the apparatus is ready for exposure, and the CPU is continuously watching the state of the exposition push¬ button 82. In the moment when the on-state of the pushbutton 82 is detected, /i.e. the button is pushed/ the second timer 216 is started and terminal £ of port 0 takes an on-state, whereby a timing pulse is transmitted to the SCR controll¬ er 240 which starts an exposure with the parameters set.

The CPU examines now the condition of the second timer 216, and when its timing has finished, the on-state is re-

OMPI leased from the terminal £ and the second timer 216 is re¬ set. This means the end of the exposure. Now a basic frequen¬ cy value -is read from the ROM 214 in the first timer 215 which corresponds to the required extent of preheating^' the filaments between subsequent exposures, and the terminals 1 to 7 of port 0 are all reset, whereby all contactors get released. The anode rotation is also stopped. The control block 200 has arrived again in the starting position and a new exposure can be set and started. From this way of operation it can be seen, that the application of the control block 200 with a microcontroller 210 therein could substantially solve all tasks connected with the coordination of various phases of operation re¬ quired for carrying out an exposure. As a result of this coordinating function the only information required for actually making exposures is the data of the three para¬ meters i.e. kV, mA and seconds which can well be reported through a standard serial data transmission line. In other words, the intelligence built in the control block 200 relieves the personal computer from performing a large number of control and checking functions, and in this way the capacity of the personal computer can freely be utiliz¬ ed for facilitating the handling and increasing the flexi¬ bility in adapting the whole system to various clinical and technical conditions.

The personal computer 300 is used for helping the X- ray personnel selecting the required mode. A preferable way of offering this help is explained in connection with FIGs. 4 to 6. FIG. 4 shows the screen of the display of the personal computer in the first selection mode when body-part selection takes place. In the left area of the screen a schematic standing human figure can be seen which is divided by app¬ ropriate contour lines in several areas, all well recong- nizable for those having at least some skill in medical art. One of these areas if flashing. It is preferable if the body-parts which can be selected, can be chosen according to .a predetermined_, order of, sequence,_ e.g. from the skull... ,._; gradually^" down ^'t the feet'. In FIG. 4 the skull is indicat- ed as flashing. Beside the human figure the right area of the screen is associated with a text window. In the text window the X-ray examinations are enlisted which can be carried out on the flashing body part. If the body part to be chosen is not the skull, the personnel should simply push a key on the standard keyboard on the personal computer associated with one step of upwardly or downwardly scroll¬ ing a picture, and in response to this event the flashing will jump to the next possible body part in upward or downward direction and the text window will comprise the list of examinations associated with the newly selected body-part. When the required body-part is flashing-, the selection can be made by pushing e. g. the "return" key in the keyboard. In that case the selected body part will stop flashing, it becomes highlighted and the cursor will jump to the first line in the list of examinations in the text window. In

FIG. 5 the selected body part is the thorax which is high¬ lighted and the text window comprises the various examin¬ ations that can be carried out in this body part. The cursor i.e. the flashing of a line can be moved up and down by the same keys as in body-part selection and the required examin¬ ation can be selected by pushing e.g. the "return" key when the cursor is in the required line. In response to the se¬ lection of the examination the selected line will stop flash¬ ing and becomes highlighted as it is indicated in FIG. 6. When the selection is made, the kV, mA and secundum values associated with that particular examination will be passed from the personal computer to the control block 200 in the form of a standard serial information sequence.

It can well be seen that this kind of selection is very easy to be learned and practically excludes the possib-

ility of any mis-setting. The number of selectable body- parts and the examinations that can be associated with a body, part can_.be varied within, wide, limits. . .. .. ....

The personal computer can provide a number of additional services for the personnel. The three parameters of the exposure_^are depending not only on the body part and on the required examination but also on a number of other factors, such as age and condition- of the individual who is to be examined. A condition can be e.g. the weight, the fact if the examined body part is plastered or if she is in pregnancy, etc. Further factors are those connected with the X-ray equipments, e.g. the quality of the film, the distance of the X-ray source from the body part /e.g. magnification/, and the presence of auxiliary equipments like a bucky-grid, etc.

The computer program required for the selection of the body-part and of the examination is rather simple and on the basis of the aforementioned information anyone skilled in programming can write it. The personal computer must be supplied with a large number of data which comprise the para¬ meter triplets associated with each selectable examination. Actually, the selection provides the address in the memory in which the acquired parameter triplet is stored. It is clear that as many of such tables of data must be stored in the memory as many different conditions can be selected.

The personnel should set these factors either before or after the selection of the examination and the body part. There are a number of factors which are constant for a given equipment or a given state of the equipment /like film-sen- sitivity, distance, bucky-grid, etc./ and these factors do not have to be set at each exposure. Alternatively, the demand of memory capacity can be decreased if some of the factors can be calculated from the .values of the parameter triplets when the associated conditions are known. The usage of a personal computer in combination with the control block 200 offers a number of advantages. First, the handling gets easier and more reliable. Furthermore, the price of personal, computers,.manufactured In..large scales is much below the price of special purpose computers. Owing to the sharing of the control functions betwen the computer and the control block, the computer has got relieved. rom a large number of special tasks, therefore it can be prog¬ rammed without the actual knowledge of the various internal operational conditions of the X-ray equipment, and the per- sonal computer will have sufficient spare capacity for servic¬ ing more than one X-ray equipment at a time, whereby X-ray centres can be formed. The excess capacity of the personal computer can also be used for recording the relevant data of the patient and for automating the administration work which has imposed a considerable load on personnel in X-ray stations,

Claims

• - 1. An a-ppara-t-us^' for setting^' the exposure parameters ^• '- such as high voltage, current and exposure time of an X- ray equipment to correspond to values defined by require¬ ments of an examination selectable by an X-ray personnel, said X-ray equipment comprises respective input ports for receiving electric signals by which said parameters can be set, characterized by comprising a control block including a microcontroller, said microcontroller comprises an inter¬ face establishing a connection towards a data transmission line, a central processor unit, a random access memory, a read only memory for storing information determining logical conditions that must be satisfied by said signals for pro¬ viding an X-ray exposure, timing means responsive to commands of said central processor unit and ports with logical states defined by said central processor unit, coupling means connected between said ports and said input ports for converting said logical states in said signals, and a personal computer connectable to said interface via said data transmission line for storing data associated • with said parameters in said microcontroller, whereby the function of control being shared betwen said control block and said personal computer in such a way, that said personal computer is programmed to determine said data by means of a dialog mode of operation with the personnel--, and said control block utilizing said data to generate said signals in the way and sequence defined by the operational require¬ ments and conditions of said X-ray equipment.

2. The apparatus as claimed in claim 1, in which said data associated with the current of the X-ray tube is represented by a frequency signal generated by said timing means, the coupling means associated with the generation of the current setting signal comprises a frequency to voltage converter receiving said frequency signal, a controlled power supply with a control input connected to the output of said converter, whereby said power supply generates an output voltage corresponding to the required current value, said ^•"•output voltage" being used to supply the filament of t^'he^'X^'-^' ray tube in said equipment.

3. The apparatus as claimed in claim 2, in which the X-ray equipment comprises a filament transformer and a chopper supplied by the output of said power supply, the output of the chopper is coupled to primary winding of said filament transformer.

4. The apparatus as claimed in claim 2, in which said central processor unit is coupled to said timing means for setting a frequency signal associated with a basic fila¬ ment frequency code when an exposure has finished, whereby said filament is preheated with a predetermined energy bet¬ ween exposures.

5. The apparatus as claimed in claim 1, in which said timing means comprises a timer set to the time of exposure as defined by said personal computer, said central processor unit is connected to the timer in such a way that the timing can be started if all conditions for the exposure are satis¬ fied; a terminal of said ports is coupled to the timer when exposure timing is enabled by said central processor unit and said terminal is coupled to timing input port of the X- ray equipment.

6. The apparatus as claimed in claim 5, in which a condition of starting an exposure being an on-state of an exposure pushbutton watched by said central processor unit.

7. The apparatus as claimed in claim 1, in which said X-ray equipment comprises a high voltage transfomer with a predetermined number of primary coils, said voltage adjust¬ ing block comprises a predetermined number of contactors coupled to said coils and a predetermined number of relays coupled respectively to control windings of said contactors, said control block comprises a kV control unit with outputs connected to said relays and inputs connected to a predeter¬ mined number of said ports having logical states determining the combination of the coils that must be activated for ob¬ taining the required high voltage.

8. The apparatus as claimed in claim 1, in which said control block having input ports for receiving feedback sig¬ nals indicating the actual status of the X-ray equipment and of various auxiliary equipments associated with the X-ray equipment.

9. The apparatus as claimed in claim 1, in which said personal computer has a memory storing coded information trip¬ lets defining said parameters depending on various different conditions selectable by said personal computer during said dialog mode.

IΠ R-B

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