CN111785240B

CN111785240B - Anti-phase interference filter active wave protection device for PET-MR working noise

Info

Publication number: CN111785240B
Application number: CN202010770989.XA
Authority: CN
Inventors: 冯刚; 高欣
Original assignee: Shanghai Universal Medical Imaging Diagnosis Center Co ltd
Current assignee: Shanghai Universal Medical Imaging Diagnosis Center Co ltd
Priority date: 2020-08-03
Filing date: 2020-08-03
Publication date: 2021-04-09
Anticipated expiration: 2040-08-03
Also published as: CN111785240A

Abstract

The anti-phase interference filtering active wave protection device for the PET-MR working noise comprises a headset ear cover (1), a gas distribution pipe (3), a main gas pipe (4) and a processing unit (5); one end of each of the first bronchus (13), the second bronchus (14) and the third bronchus (15) is respectively connected with a first sound wave receiver (10), a second sound wave receiver (11) and a sound wave releaser (12) in the headset ear muff (1), and the other end of each of the first bronchus, the second bronchus (14) and the third bronchus is respectively connected with a first piezoelectric sensor (51), a second piezoelectric sensor (57) and a sound wave generator (56) in the processing unit (5); the active mode and the passive mode are combined to cooperate with the synchronous double-mode work to effectively reduce noise, wherein the active noise reduction working mode utilizes the same frequency and the same amplitude to perform opposite phase interference to offset noise reduction, peak clipping noise reduction is performed, the manufacturing is simple, the cost is lower, the use and maintenance are safe and convenient, and the influence on PET acquisition is effectively reduced.

Description

Anti-phase interference filter active wave protection device for PET-MR working noise

Technical Field

The invention relates to a structure improvement technology of an auxiliary noise protection device of IPC classification A61B5/055 containing electromagnetic resonance [ EMR ] or nuclear magnetic resonance [ NMR ], such as magnetic resonance imaging or G01R33/20 magnetic resonance imaging scanning detection equipment, belonging to the field of nuclear magnetic resonance safety protection, in particular to an anti-phase interference filtering active wave protection device for PET-MR working noise.

Background

PET-MRI is a new technology that combines positron emission computed tomography, i.e. the molecular imaging function of PET, with the excellent soft tissue contrast function of magnetic resonance imaging MRI. PET-MRI can image diseased cells that spread in soft tissue. It enables the patient to be scanned in various modes, and the system can also collect PET and MR images separately. Compared with other means, the PET/MRI examination has high sensitivity and good accuracy, and has early detection and early diagnosis values for a plurality of diseases, especially tumors and the most common heart and brain diseases. Due to the relationship of gradient fields, various types of high-intensity noises generated during MRI scanning can generate a series of adverse effects on the examinee and the operator who is in a scanning workshop for a long time, and symptoms such as anxiety, language communication disorder, tinnitus, light headedness and the like appear, and more serious persons can cause temporary or permanent hearing threshold change and even deafness.

The gradient field produces a higher level of noise with a rapidly switched scan sequence, such as a single-shot echo planar diffusion weighting sequence. The stronger the gradient field, the faster the switching, and the greater the noise. The output of gradient parameters such as the switching rate or strength of the gradient is changed, and the generated noise is different in size. The noise level is influenced more strongly by the scanning parameters (e.g. FOV, TR) than by the gradient field, the thinner the layer thickness, the smaller the FOV, the shorter the TR, and the stronger the audible noise. The magnitude of the MRI system's audible noise depends on the hardware structure of the MRI system and the surrounding environment, in addition to the gradient switching rate, scan sequence parameters. The presence or absence of sound insulation in MRI equipment, the coil material, structure, various components supporting the gradient coil, and the like all affect the transmission of sound, and change the magnitude of noise transmitted into the human ear.

The general appearance of MRI system noise is: (1) the noise at different positions in the magnet is different in magnitude, the sound pressure level tester measures at different positions along the Z direction from the isocenter position of the magnet system, and each point measures different noise values, wherein the noise at the inlet of the magnet hole is the largest, so that the auditory harm to an examination item examinee (such as pelvic cavity examination) entering the magnet in advance is larger; (2) when a volunteer enters the magnet, the noise is larger than that measured at the isocenter position when the magnet is empty or a water film is released, and the influence of the entrance of the volunteer into the magnet on the noise is prompted; (3) the noise generated by different image scanning directions is different in size, and the noise generated by coronal plane scanning is larger than that generated by transverse plane and sagittal plane.

The system noise of MRI mainly comes from the switching of the gradient field, the gradient coil is located in the main magnetic field, and the current that changes fast in the coil will vibrate under the effect of Lorentz force and produce the noise according to left-hand law, mainly show as the knocking sound of knocking, beating and similar clock and watch. The noise of the same field intensity and different machine types is different, the noise of the same machine type and different field intensities is also different, and the noise is enhanced along with the increase of the field intensity and the imaging speed.

The noise of the MRI system seriously hinders the communication between the physician and the subject, so that the physician cannot know the feedback of the patient in time, thereby affecting the image quality of some functional imaging and possibly even causing hearing impairment of the subject and the operator. The effects of noise on auditory function are mainly manifested as decreased auditory sensitivity, increased threshold, decreased speech reception and signal discrimination, and in severe cases, deafness. Hearing impairment can occur in any part of the auditory circuit, including the external auditory canal, middle ear conduction structures, the cochlea, cochlear nerves, and the central auditory pathway. Noisy hearing impairment can occur in people of all ages. Hearing impairment causes a number of physiological and psychological problems, which affect the development of auditory and speech functions in children and social and occupational problems in adults. Noise is more damaging to people at high risk.

The sound pressure level of the noise peak of the MRI system is 120-130 dB (A), and the noise in the range mainly damages cochlear hair cells. Under the action of high sound pressure for a long time, cells are in a state of high metabolism and high load, resulting in failure and death. Noise can cause cell damage by the following mechanisms: (1) the noise causes the change of the blood flow state, the blood oxygen level and the blood vessel shape of the cochlear hair cells, so that the cells are subjected to ischemia and hypoxia, and the cells are damaged by the increase of oxygen free radicals and apoptosis factors. (2) The early stage cochlear structures stimulated by noise produce inflammatory cytokines including tumor necrosis factor, interleukin-1, interleukin-6, which cause a series of inflammatory responses that result in hair cell damage. (3) After noise stimulation, mitochondrial DNA of the cell A3243G is mutated, the cell metabolism is abnormal, and the inner and outer hair cells lose functions to cause hearing loss.

The patent documents of the corresponding technology are less disclosed.

Chinese patent application 201520167510.8, filed by southern medical university, relates to a noise reduction protection device on a nuclear magnetic resonance instrument. The utility model discloses a protector that makes an uproar falls in nuclear magnetic resonance, for the cover body that has at least one open-ended of being made by non-magnetic material, the cover body has shell and inner shell, space between shell and the inner shell sets up to the vacuum. The double-layer tube walls of the cover body are arranged into a vacuum structure, noise transmitted to the inner layer of the vacuum tube is reduced by utilizing the characteristic that sound cannot be transmitted in vacuum, and effective noise protection is carried out on testers or detection parts such as fetuses and the like which are not suitable for bearing over-strong noise or other scanned objects such as animals and the like.

Chinese patent application 201820729560.4 discloses a protector that makes an uproar falls in medical science nuclear magnetic resonance, including falling the protection body of making an uproar, the cross-section of falling the protection body of making an uproar sets up to square tubulose form, fall the protection body of making an uproar by the same right side board of making an uproar that falls of structural shape size, fall the top side board of making an uproar, fall the left side board of making an uproar and fall the bottom side board of making an uproar and connect integrative concatenation in proper order end to end and form, from left to right press from both sides from left to right between inlayer toughened glass and the outer toughened glass and be equipped with noise elimination sponge layer and noise elimination baffle layer in proper order, inside the plywood on noise elimination baffle layer, the position department of staggering support linking post pole still evenly arranged the noise.

Chinese patent application 201721400886.4 discloses a noise reduction protection device for nuclear magnetic resonance instrument, which comprises a cover body, wherein the cover body comprises a first cover body, a second cover body and a third cover body, the semi-closed cover body reduces the noise in the internal main body space, the space between the first cover body and the second cover body is set to be vacuum, the noise transmitted to the inside of the first cover body and the second cover body is reduced by utilizing the principle that the sound can not be transmitted in vacuum, a sound absorption layer filled in the space between the second cover body and the third cover body can attenuate the reflection energy of an incident sound source, the noise reduction effect is achieved, when a human body lies on a flat plate, the positions of sound insulation ear plates are slid, the left and right ear parts of the human body are attached to the sound insulation ear parts, the inside of the sound insulation ear plates is filled with sound insulation felts, the sound insulation is further performed, after the positions of the sound insulation ear plates are determined, a detachable inserting plate is, the pins at the lower end of the detachable inserting plate are inserted into the corresponding inserting holes, so that the sound insulation ear plates are fixed.

The main noise reduction techniques that have been disclosed now include both passive and active types.

Passive methods primarily involve changing the gradient coils of the MRI system, changing the mechanical structure of the gradient coils, changing the coil size or material to reduce mechanical vibrations, or changing the current through the gradient coils, replacing the gradient created by the changing current with a mechanical rotation of the dc gradient to reduce noise. Noise effects can also be reduced by changing the MRI sequence, which can be reduced by changing the scan sequence or sequence parameters, since it is the particular scan sequence that dominates the noise level rather than the MRI system structure itself. If SE sequences are used instead of gradient echo sequences and the gradient switching rate is minimized during the scan, the noise level can be significantly reduced. Noise reduction can also be achieved by blocking the noise propagation path: noise diffuses through 2 routes of air propagation and solid contact diffusion. The noise is directly transmitted to the ear of the examinee by the gradient coil through the 2 diffusion modes, or other parts are caused to vibrate, a new noise source is generated, and then the new noise source is transmitted to the ear of the examinee. The method that sponge earplugs are placed into external auditory canals on two sides or hearing protection earphones (earmuffs) are used for reducing noise entering inner ears is commonly adopted at present, the noise attenuation amount of the earmuffs is 31-38 dB, and the attenuation amount of the earplugs is 10-30 dB.

Active noise reduction techniques are disclosed to reduce, if not eliminate, the noise emitted by the overall structure without weakening the gradient field to be generated by the overall coil, primarily by introducing an additional coil that subtly cancels the vibration modes of the overall coil's physical structure. In addition, active noise reduction also relates to noise reduction technologies such as ANC, ENC, CVC and DSP, and the effect is limited.

The existing noise reduction earphone generally adopts a sound insulation earphone to be isolated from the outside, so that the outside noise is reduced, but the mode of the sound insulation earphone with a physical structure has the following defects:

1) the volume is large, and the head needs to be clamped on the head when in use, so the head is too heavy;

2) because of the physical sound insulation mode, the clamping force of the earphone applied between the two ears is too large, so that the user is uncomfortable when wearing the earphone and feels sultry;

3) the sound insulation effect is not very good and a lot of noise still leaks into the ear.

Disclosure of Invention

It is an object of the present invention to provide an anti-interference filtering active wave shielding device for PET-MR operating noise that solves the above mentioned prior art problems.

The aim of the invention is achieved by the following technical measures: comprises a headset ear shield, a gas distribution pipe, a main gas pipe and a processing unit; the processing unit is connected with two branch air pipes through a main air pipe, at least one group of first branch air pipe, second branch air pipe and third branch air pipe are bunched in the branch air pipes, one ends of the first branch air pipe, the second branch air pipe and the third branch air pipe are respectively connected with a first sound wave receiver, a second sound wave receiver and a sound wave releaser in a headset ear cover, and the other ends of the first branch air pipe, the second branch air pipe and the third branch air pipe are respectively connected with a first piezoelectric sensor, a second piezoelectric sensor and a sound wave generator in the processing unit; in the processing unit, the first piezoelectric sensor is connected with the gain compensation amplifier through a circuit and then connected to the phase inverter, meanwhile, the second piezoelectric sensor is connected to the phase inverter through the phase compensation amplifier, and the phase inverter is connected to the sound wave generator through the power amplifier and the sound source in sequence. The active and passive modes are combined to cooperate with a synchronous dual-mode work to effectively reduce noise, wherein the active noise reduction working mode utilizes the same frequency and the same amplitude to carry out opposite phase interference cancellation noise reduction.

Particularly, the earphone body is of an arc-shaped elastic structure, and two sides of the opening of the earphone body are respectively provided with a headset ear cover.

Especially, the inside foam filling material that fills of headphone earmuff, first sound wave receiver, second sound wave receiver and sound wave releaser are installed respectively to the outside both sides of headphone earmuff.

Particularly, two gas distribution pipes are bundled in the main gas pipe, each gas distribution pipe is bundled with a group of a first gas distribution pipe, a second gas distribution pipe and a third gas distribution pipe, and the foreign currency gaps of the two gas distribution pipes in the main gas pipe are filled with foam filling materials at intervals.

In particular, the headphone ear cups and the processing unit are provided as two parts, respectively, a near working magnet and a far working magnet, wherein the headphone ear cups are provided as the near magnet part in the PET-MR device and the processing unit part is located in the operating room remote from the magnets.

Particularly, noise in a cavity of the PET-MR equipment is collected by a first sound wave receiver, the noise is transmitted to a first piezoelectric sensor in a processing unit through a gas pipe system consisting of a main gas pipe, a gas distribution pipe and a first gas distribution pipe and converted into an electric signal, the electric signal is amplified by a gain compensation amplifier and then is connected into a phase inverter, phase conversion is performed on the electric signal, the electric signal is converted into sound waves through a sound source after power amplification of a power amplifier, the sound waves are converted into sound waves through the sound source and then are connected back through a third gas distribution pipe and transmitted into a sound wave releaser in an earmuff of the headset, and the sound waves are played in the headset to realize active noise.

Especially, the noise active protection can not completely cancel part of the noise, the noise is collected by the second sound receiver and then transmitted to the second piezoelectric sensor, the sound wave is converted into an electric signal, the electric signal is amplified by the phase compensation amplifier and phase compensated and then transmitted to the inverter for reversal, and then the electric signal is converted into the sound wave by the sound source after the power amplification of the power amplifier, and then the sound wave is transmitted to the sound wave releaser in the ear muff of the headset through the third branch air pipe and played in the headset.

The invention has the advantages and effects that: on the basis of passive noise protection, the device is synchronously combined with the conduction of an air pipe system, and carries out sound wave-electric signal back-passing through reverse processing, and actively interferes noise sound waves, so that the device has the advantages of peak clipping and noise reduction, simple manufacture, lower cost, safe and convenient use and maintenance, and effective reduction of the influence on PET acquisition.

Drawings

Fig. 1 is a schematic structural diagram of embodiment 1 of the present invention.

Fig. 2 is a schematic structural diagram of a single earmuff in embodiment 1 of the present invention.

Fig. 3 is a schematic cross-sectional view of a main air pipe in embodiment 1 of the present invention.

Fig. 4 is a schematic view of a working system in embodiment 1 of the present invention.

The reference numerals include:

the earphone comprises a headset ear muff 1, a headset body 2, a gas distribution pipe 3, a main gas pipe 4, a processing unit 5 and a far magnetic field/near magnetic field partition wall 6; a first sound wave receiver 10, a second sound wave receiver 11, a sound wave releaser 12, a first bronchus 13, a second bronchus 14, a third bronchus 15, and a foam filling material 16; a first piezoelectric sensor 51, a gain compensation amplifier 52, an inverter 53, a power amplifier 54, a sound source 55, an acoustic wave generator 56, a second piezoelectric sensor 57, and a phase compensation amplifier 58.

Detailed Description

The principle of the invention is that the frequency band of the human ear most sensitive to sound is distributed around 4 kHz. Since the human ear has different sensitivities to sounds of different frequencies, the sound intensity is expressed by an equivalent weight db (a), and the noise exceeds 85db (a), which is liable to cause hearing impairment. The data show that the system noise of 0.23T and 3.0T MRI is (82.56 +/-0.10), (118.46 +/-1.30) dB (A), and the peak sound pressure level of the 3.0T MRI sequence is 125-130 dB (A). It follows that the peak sound pressure level of high field MRI systems has significantly exceeded noise safety standards.

In the invention, active and passive modes are combined to cooperate with synchronous dual-mode work to effectively reduce noise, wherein the active noise reduction working mode utilizes the same frequency and the same amplitude to carry out opposite phase interference cancellation noise reduction.

In the invention, a working magnet of the PET-MR device is taken as a reference object, and the working structure of the invention is arranged into a near magnet part and a far magnet part, wherein the near magnet part adopts air conduction, a signal processing part, namely a processing unit 5 is positioned in an operation room far away from the magnet, and personnel in a cavity of the PET-MR scanner is close to the magnet and positioned at the core of a noise field, and can wear a headset earmuff 1 and a headset body 2 so as to obtain effective protection.

The invention comprises the following steps: headset earmuffs 1, a gas distribution pipe 3, a main gas pipe 4 and a processing unit 5.

The invention is further illustrated by the following figures and examples.

Example 1: as shown in fig. 1, the processing unit 5 is connected to two branch air tubes 3 through a main air tube 4, at least one set of a first branch air tube 13, a second branch air tube 14 and a third branch air tube 15 is bundled in the branch air tubes 3, one end of the first branch air tube 13, one end of the second branch air tube 14 and one end of the third branch air tube 15 are respectively connected to a first sound wave receiver 10, a second sound wave receiver 11 and a sound wave releaser 12 in the headphone ear muff 1, and the other end of the first branch air tube 13, the second branch air tube 14 and the other end of the third branch air tube 15 are respectively connected to a first piezoelectric sensor 51, a second piezoelectric sensor 57 and a sound wave generator 56 in the processing unit 5; in the processing unit 5, the first piezoelectric sensor 51 is electrically connected to the gain compensation amplifier 52 and then connected to the inverter 53, the second piezoelectric sensor 57 is connected to the inverter 53 through the phase compensation amplifier 58, and the inverter 53 is connected to the acoustic wave generator 56 through the power amplifier 54 and the sound source 55 in sequence.

In the foregoing, the earphone body 2 is an arc-shaped elastic structure, and the two sides of the opening of the earphone body 2 are respectively provided with a headset ear muff 1.

In the foregoing, as shown in fig. 2, the interior of the headphone ear cup 1 is filled with the foam filling material 16, and the first sound wave receiver 10, the second sound wave receiver 11 and the sound wave releaser 12 are respectively mounted on two sides of the exterior of the headphone ear cup 1.

In the above, as shown in fig. 3, two branch air pipes 3 are bundled in the main air pipe 4, a group of first branch air pipe 13, second branch air pipe 14 and third branch air pipe 15 are bundled in each branch air pipe 3, and the gap between the foreign currency of the two branch air pipes 3 in the main air pipe 4 is filled with the foam filling material 16 at intervals.

In the embodiment of the invention, the external part of the headphone ear muff 1 is made of polycarbonate, the headphone body 2 is made of polyurethane or polyethylene and is made into an arch-shaped hoop structure, the arch-shaped hoop structure is mutually connected with the headphone ear muff 1 with a protective ear cap structure and is used for covering the two ears of a detected patient, the external component and the internal component of the headphone ear muff 1 are made of polycarbonate or polystyrene, although the foam filling material 16 is added in the headphone ear muff to assist in isolating noise, the headphone ear muff belongs to passive protection, and the protection effect is inevitably influenced along with the aging of equipment.

In the embodiment of the invention, as shown in fig. 4, a far magnetic field/near magnetic field partition wall 6 is taken as a reference object, a patient to be detected is in a room for arranging MRI scanner equipment and possibly in a cavity of the MRI scanner, the head of the patient to be detected is worn with an earphone body 2, and two ears respectively shield a headset earmuff 1; meanwhile, the processing unit 5 is located in an operation room with a far magnetic field/near magnetic field partition wall 6 as a partition; the headphone ear muffs 1 are connected with the processing unit 5 through one or two groups of a first bronchus 13, a second bronchus 14 and a third bronchus 15.

In the embodiment of the invention, the first sound wave receiver 10 collects noise in the cavity of the MRI scanner, the noise is transmitted to the first piezoelectric sensor 51 in the processing unit 5 through the air pipe system formed by the main air pipe 4, the air distribution pipe 3 and the first air distribution pipe 13 and converted into an electric signal, the electric signal is amplified by the gain compensation amplifier 52 and then is connected to the phase inverter 53, the phase is converted pi, the power is amplified by the power amplifier 54, the electric signal is converted into sound waves by the sound source 55 and then is connected back by the third air distribution pipe 15 and is transmitted to the sound wave releaser 12 in the ear muff 1 of the headset, and the sound waves are played in the headset to implement active noise protection.

In the embodiment of the present invention, the noise active protection cannot completely cancel part of the noise, and the noise is collected by the second sound receiver 11 and then transmitted to the second piezoelectric sensor 57, the sound wave is converted into an electric signal, the electric signal is amplified and phase-compensated by the phase compensation amplifier 58 and then transmitted to the inverter 53 for inversion, and then the electric signal is converted into a sound wave by the sound source 55 after power amplification by the power amplifier 54, and then the sound wave is received back by the third bronchus 15 and transmitted to the sound wave releaser 12 in the ear muff 1 of the headphone for playing in the headphone.

In the embodiment of the invention, the equipment system has the characteristics that:

1) the advantages of passive noise protection equipment are combined, and active systems are added;

2) according to the magnitude of the magnetic field, different signal transmission modes are adopted to ensure that the signals are not influenced by the magnetic field;

3) a feedback loop is adopted to eliminate noise as completely as possible;

4) the manufacturing is simple, and the cost is low;

5) the inner part of the cavity is made of resin and engineering plastics, so that the influence on PET acquisition is effectively reduced.

Claims

1. The anti-phase interference filtering active wave protection device for the PET-MR working noise comprises a headset ear cover (1), a gas distribution pipe (3), a main gas pipe (4) and a processing unit (5); the earphone is characterized in that a processing unit (5) is connected with two branch air pipes (3) through a main air pipe (4), at least one group of first branch air pipe (13), second branch air pipe (14) and third branch air pipe (15) are bundled in the branch air pipes (3), one end of each of the first branch air pipe (13), the second branch air pipe (14) and the third branch air pipe (15) is respectively connected with a first sound wave receiver (10), a second sound wave receiver (11) and a sound wave releaser (12) in a headset earmuff (1), and the other end of each of the first branch air pipe (13), the second branch air pipe (14) and the third branch air pipe (15) is respectively connected with a first piezoelectric sensor (51), a second piezoelectric sensor (57) and a sound wave generator (56) in the processing unit (5); in the processing unit (5), a first piezoelectric sensor (51) is connected with a gain compensation amplifier (52) through a circuit and then connected to an inverter (53), meanwhile, a second piezoelectric sensor (57) is connected to the inverter (53) through a phase compensation amplifier (58), and the inverter (53) is connected to an acoustic wave generator (56) through a power amplifier (54) and a sound source (55) in sequence;

the earphone body (2) is of an arc-shaped elastic structure, and two sides of the opening of the earphone body (2) are respectively provided with a head-wearing earphone ear cover (1);

the interior of the head-wearing earphone ear muff (1) is filled with a foam filling material (16), and a first sound wave receiver (10), a second sound wave receiver (11) and a sound wave releaser (12) are respectively arranged on two outer sides of the head-wearing earphone ear muff (1);

two gas distribution pipes (3) are bundled in a main gas pipe (4), each gas distribution pipe (3) is bundled with a group of a first gas distribution pipe (13), a second gas distribution pipe (14) and a third gas distribution pipe (15), and gaps between the outer walls of the two gas distribution pipes (3) in the main gas pipe (4) are filled with foam filling materials (16) at intervals;

the active and passive modes are combined to cooperate with a synchronous dual-mode work to effectively reduce noise, wherein the active noise reduction working mode utilizes the same frequency and the same amplitude to carry out opposite phase interference cancellation noise reduction.

2. The anti-interference filter active wave shielding device for PET-MR operating noise according to claim 1, characterized in that the headphone ear cup (1) and the processing unit (5) are arranged as two parts, respectively a near operating magnet and a far operating magnet, with the operating magnet of the PET-MR device as a reference, wherein the headphone ear cup (1) is arranged as the near magnet part in the PET-MR device and the processing unit (5) part is located in the operating room remote from the magnets.