RU2045225C1 - Nuclear magnetic tomograph for diagnosing internal diseases - Google Patents

Abstract

FIELD: medical engineering. SUBSTANCE: this tomograph incorporates successively connected control panel 1, personal computer 2, electronic unit 3 whose first output is connected to input of transmitter 17 whose first output is connected to input of head radio-frequency coil 7 and whose second output is connected to input of body radio-frequency coil 8. Outputs of these coils are connected to second input of electronic unit 3 via preamplifier 18. Second output of electronic unit 3 is connected to output of power source that energizes electromagnet 4. Third output of electronic unit 3 is associated with inputs n of power sources 14 that feed power to gradient coils 6 whose outputs are connected to inputs n of gradient coils. Disclosed tomograph further includes correction coils 5, patient's table 15, cooling system 16, choke with controlled winding 10 and voltage divider 11 which is composed of resistor 12 and n potentiometers 13. EFFECT: more sophisticated design. 2 dwg

Description

 The invention relates to medicine and can be used in medical equipment for the diagnosis of internal diseases according to the invention of the internal structure of the test body, obtained by computer construction.

 Known tomograph "Magnaview MR Imaging Sistem" containing a control panel, an electronic computer (computer), an electronic unit, a transmitter, an amplifier, power sources of correction and gradient coils, radio frequency coils for the head and body, an electromagnet, gradient and correction coils, electromagnet power supply, cooling system, patient table.

 The disadvantage of this tomograph is the use of five independent sources for the power of the correction coils, according to the number of groups of correction coils, which leads to a decrease in the temporary stability of the magnetic field due to the presence of random fluctuations in the output voltages of mutually independent power supplies of the electromagnet and each group of correction coils.

 Since the correcting coils are designed to create magnetic fields, which, when combined with the field of the electromagnet, give a field of high uniformity, the power of the electromagnet and correcting coils from independent sources introduces an additional factor of field inconstancy in the form of random fluctuations in the output voltages of the power sources of the correcting coils. The quality of the image of the internal structure of the subject of study obtained by the tomograph also depends on the degree of constancy of the magnetic field, understood as geometric uniformity with temporary stability. If geometric uniformity is achieved by the accuracy of the installation of the electromagnet coils, then the temporary stability depends mainly on the stability of the power sources.

 Field instability ultimately leads to poor image quality.

 In addition, the electromagnet power supply has, as one of the stabilizing devices, an adjustable autotransformer with a mechanical electric drive with moving contacts. Being a sufficiently inertial device, it complicates the working conditions of the subsequent stabilization stages, which ultimately reduces the source stability level. Moving contacts reduce the reliability of the entire tomograph.

 The aim of the invention is to improve image quality by increasing the degree of stability of the magnetic field, increasing reliability due to significant simplification and cheapening.

 The goal is achieved by the fact that an NMR scanner for diagnosing internal diseases, comprising a control panel, a personal electronic computer (PC) and an electronic unit, the first output of which is connected to the input of the transmitter, the first output of which is connected to the input of the radio frequency coil for the head, and the second with the input of the radio frequency coil for the body, the outputs of which through the preamplifier are connected to the second input of the electronic unit, the second output of the electronic unit is connected to the output of the power source electromagnet, the third output of the electronic unit is connected to the inputs of n power supplies of the gradient coils, the outputs of which are connected to the inputs of n gradient coils, m correction coils, a patient table and a cooling system, characterized in that a choke with a controlled winding and a voltage divider are introduced into it, consisting from a resistor and m potentiometers, the fixed contacts of which are combined and connected to the first output of the resistor, which is connected to the output of the electromagnet's power source, the second output of the resistor is connected to Odom electromagnet and to first terminals of m correction coils, the second terminals of which are connected to the respective movable contacts of potentiometers, throttle input with the control winding is connected to a network, and an output coupled to the second input of the electromagnet power source, a second output connected to the control winding of the choke.

 Figure 1 presents a block diagram of an NMR scanner for the diagnosis of internal diseases; figure 2 an example implementation of the electronic unit.

 An NMR scanner for diagnosing internal diseases contains a control panel 1, a PC 2, an electronic unit 3, an electromagnet 4, corrective 5 and gradient 6 coils, radio frequency coils 7 and 8 for the head and body, an electromagnet 9 power supply with a choke with a controlled winding 10 , a voltage divider 11, consisting of a resistor 12 and potentiometers 13, power supplies of the gradient coils 14, a patient table 15, a cooling system 16, a transmitter 17 and a preamplifier 18.

 The electronic unit (figure 2) contains a controller unit 19, a filter unit and analog-to-digital converters 20, a detector unit 21, an RF generator unit 22, a pulse shaper unit 23, a signal level shaper unit 24, a gradient pulse shaper unit 25, a power supply 26.

 The tomograph works as follows.

 Before starting the scanning process, the tomograph is returned to its original state. When voltage is supplied from the control panel 1, the electronic unit 3, the PC 2, the inductor with the controlled winding 10, the electromagnet 9 power supply, the power supplies 14, the cooling system 16, the transmitter 17, the PC preamplifier give the initial data for the operation of the blocks 19, 20, 21 , 22, 23, 24, 25 of the electronic unit 3.

 The current from the network is supplied to the inductor 10, and from it to the power source 9, while the voltage stabilization at the output of the inductor is carried out by a controlled winding fed by direct current. The current from the source 9 through the resistor 12 enters the winding of the electromagnet 4. Part of the current, depending on the resistance value of the potentiometers 13 of the voltage divider 11, is supplied to the correction coils 5.

 The transmitter 17, the preamplifier 18, the power supplies of the gradient coils 14 are in standby mode of the input signal from the blocks 21, 22, 25 of the electronic unit 3.

 Using the control panel 1, a scan mode is selected and its parameters are set. The tomograph provides for the possibility, if necessary, with a handle for adjusting the field of the electromagnet, by connecting one of the inputs of the source 9 to the output of block 25 of the electronic block 3.

 Simultaneously with the preparation of the tomograph, the patient is prepared for the study. It is located motionless on the table 15 and after that, together with the movable part of the table, moves so that the area of the body of interest to the doctor is in the zone of a uniform field.

 This completes the preparation of the tomograph for scanning mode.

 At the command of the “start of scanning” personal computer, the tomograph is controlled by unit 23 of the electronic unit 3, which generates time intervals corresponding to a particular scanning mode and commands in them that establish the sequence of switching on, switching off, the shape and size of exciting pulses, and other parameters of the mode, and the PC itself receives and processes scan data.

 Blocks 4, 5, 9, 10, 11 continue to work in the mode established during preparation until the tomograph is turned off.

 The sequence of pulses determined from the selected scanning mode from block 23 through block 24 of electronic block 3 is supplied to source 14 and to gradient coils 6, the magnetic field of which in a special way violates the uniformity of the field of the electromagnet in the study area, highlighting the layer in which the image of the object in it is obtained research.

 At a certain point in time, set in accordance with the selected mode by the block 23 of the electronic block 3, the pulse from the blocks 21 and 22 is supplied to the transmitter 17, amplified, modulated in it and fed to a particular 7 or 8 radio frequency coil. A radiofrequency coil emits pulses of a magnetic field, exciting nuclei of the patient’s body material. In the intervals between pulses, it also receives responses from calming nuclei and feeds into the preamplifier 18, from where it enters sequentially into the detector 21 and the block 20 of filters and analog-to-digital converters of the electronic unit 3, getting further directly into the PC, being the subject of mathematical processing and the basis for image building.

 At the end of the scan, the image of the layer of the investigated area appears on the screen, and the tomograph enters the standby mode for the next scan.

 Compared with the prototype, an NMR tomograph for diagnosing internal diseases is significantly simplified by removing five power sources, which are precision DC stabilizers, from its composition. Instead, they use a simple device that is highly reliable, while eliminating the influence of the instability of each source. The use of a contactless inductor with a controlled winding fed by direct current instead of an autotransformer with moving contacts is also a significant increase in stability and reliability. These measures increase the stability of the magnetic field and, ultimately, the image quality.

 Thus, this tomograph provides, in comparison with the prototype, improved image quality, increased reliability by simplifying the circuit and reducing the cost.

Claims (1)

 NMR TOMOGRAPH FOR DIAGNOSTIC OF INTERNAL DISEASES, containing a control panel connected in series, a personal electronic computer and an electronic unit, the first output of which is connected to the input of the transmitter, the first output of which is connected to the input of the radio frequency coil for the head, and the second to the input of the radio frequency coil for the body the outputs of which through the preamplifier are connected to the second input of the electronic unit, the second output of the electronic unit is connected to the output of the electromagnet power source, the third output is The unit block is connected to the inputs of n gradient coil power supplies, the outputs of which are connected to the inputs of n gradient coils, m correction coils, a patient table and a cooling system, characterized in that a choke with a controlled winding and a voltage divider consisting of a resistor and n potentiometers, the fixed contacts of which are combined and connected to the first output of the resistor, which is connected to the output of the power supply of the electromagnet, the second output of the resistor is connected to the input of the electromagnet and the first outputs s m correction coils, the second terminals of which are connected to the respective movable contacts of potentiometers, throttle input with the control winding is connected to a network, and an output coupled to a second input of the electromagnet power source, a second output connected to the control winding of the choke.