A method for estimating the sound power level of the operational noise of a magnetic resonance imaging device

Abstract

The present application relates to the field of vibration test technology and vibration signal analysis, in particular to a method for estimating the sound power level of the working noise of a magnetic resonance imaging device. The method converts the vibration signal ① generated on the surface of the machine shell when the magnetic resonance imaging device is working into an audio file, uses the method of playing the audio file to transfer the noise generated when the magnetic resonance imaging device is working to a quiet laboratory, and then finds the vibration signal ② generated on the surface of the measured vibration object at the vibration target point in the quiet laboratory from all the audio files with the sound volume played in the quiet laboratory. The root mean square value RMS2 calculated from the vibration signal ② is consistent with the root mean square value RMS1 of the vibration signal ①. At this time, the sound power level value of the sound level meter represents the estimated value of the sound power level of the noise generated when the magnetic resonance imaging device is working. The method solves the difficulties and problems faced by the existing evaluation of the sound power level of the noise generated when the magnetic resonance imaging device is working.

Description

Technical Field

[0001] This invention relates to the fields of vibration testing technology and vibration signal analysis, specifically to a method for estimating the sound power level of operating noise in a magnetic resonance imaging device. Background Technology

[0002] The evaluation of the sound power level of noise generated by magnetic resonance imaging (MRI) equipment during operation is crucial for ensuring that the sound power level remains within acceptable ranges for the human body. Sound power levels exceeding these ranges can cause symptoms such as dizziness, headaches, and ear discomfort. However, it is impossible to directly measure the sound power level of MRI equipment during operation using a sound pressure level meter, nor is it possible to collect contact vibration signals using sensors.

[0003] Currently, some researchers use formulas to convert vibration signals into sound power levels, aiming to evaluate the sound power level of noise generated by magnetic resonance imaging (MRI) equipment during operation. However, these formulas are theoretical, and in practical applications, factors such as surface materials and shapes are difficult to determine, making it hard to guarantee the accuracy of the calculation results. In other words, there is currently no effective technical means to evaluate the sound power level of noise generated by MRI equipment during operation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for estimating the sound power level of the operating noise of a magnetic resonance imaging (MRI) device, so as to solve the problem that existing methods are difficult to evaluate the sound power level of the noise generated by the MRI device during operation in practical engineering.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for estimating the sound power level of operating noise in a magnetic resonance imaging (MRI) device includes the following steps:

[0007] Step a: Use a laser vibrometer to acquire the vibration signal ① generated on the surface of the housing when the magnetic resonance imaging equipment is working, and calculate the root mean square value RMS1 of the vibration signal ①; the vibration signal ① is vibration acceleration, vibration velocity or vibration displacement.

[0008] Step b: Convert the vibration signal ① into a sound file;

[0009] Step c: Place a loudspeaker, a sound pressure meter, a laser vibrometer, and the object to be tested in a silent laboratory; play a sound file using the loudspeaker, measure the sound power level generated by the sound file using the sound pressure meter, and simultaneously use the laser vibrometer to obtain the vibration signal ② generated by the sound file on the surface of the object to be tested; calculate the root mean square value (RMS2) of the vibration signal ②.

[0010] Step d: Change the volume of the loudspeaker multiple times to obtain the root mean square value (RMS2) of the vibration signal ② of the surface of the tested object at different sound power levels. Stop the test when RMS2 is consistent with RMS1. The value corresponding to the sound pressure meter at this time is used as the estimated sound power level of the noise generated when the magnetic resonance imaging equipment is working.

[0011] Furthermore, in step b, a conversion program is written using MATLAB, Python, or other software to convert the vibration signal ① into a sound file; the converted sound file format is WAV, MIDI, MP3, WMA, etc.

[0012] Furthermore, in step c, the silent laboratory is a laboratory with an ambient noise level of 0 dB; the loudspeaker includes, but is not limited to, devices that can play sound files, such as a recorder; the sound pressure meter includes all devices that can measure sound pressure levels; the laser vibration meter includes all devices that can use lasers to collect vibration signals in a non-contact manner; and the object being measured is a rigid object that is damped and reflective.

[0013] Furthermore, the object being tested for vibration includes flat steel plates, hard plastic plates, etc.

[0014] Furthermore, the method for determining whether the root mean square values ​​(RMS1) and RMS2 of the vibration signal are consistent in step d includes matching of graphs and matching of numerical values.

[0015] This invention provides a method for estimating the sound power level of noise generated during the operation of a magnetic resonance imaging (MRI) device. The method involves converting the vibration signal ① generated on the surface of the MRI device's casing during operation into an audio file. This audio file is then played back to transfer the noise generated during MRI operation to a quiet laboratory. From all audio files played at various volumes in the quiet laboratory, the vibration signal ② generated at a specific volume on the surface of the tested object at a vibration measurement point is identified. Based on this vibration signal ②, an estimated sound power level representing the noise generated during MRI operation is determined. This process utilizes mature technologies such as non-contact vibration signal acquisition using a laser vibrometer, calculation of the root mean square (RMS) value of the vibration signal, and conversion of the vibration signal into an audio file. This addresses the difficulties and problems encountered in evaluating the sound power level of noise generated during MRI operation, thus forming an effective method for estimating the sound power level of noise generated during MRI operation. Attached Figure Description

[0016] Figure 1 This is a flowchart of an example implementation. Detailed Implementation

[0017] The present invention will now be described in conjunction with the accompanying drawings and embodiments. Those skilled in the art should understand that the drawings provided herein are for illustrative purposes only and are not necessarily drawn to scale.

[0018] Unless the context explicitly requires it, the words "comprising" or "including" as used throughout the specification and claims should be interpreted as including rather than exhaustive or exclusive: that is, "including but not limited to".

[0019] like Figure 1 As shown in the figure, this embodiment provides a method for estimating the sound power level of the operating noise of a magnetic resonance imaging device, which includes the following steps:

[0020] Step a. Use a laser vibrometer to acquire the vibration signal ① generated on the surface of the magnetic resonance imaging device during operation. The vibration signal can be vibration acceleration, vibration velocity, and / or vibration displacement. When the vibration signal is vibration acceleration, the vibration displacement is obtained through two integrations; when the vibration signal is vibration velocity, the vibration displacement is obtained through one integration. This embodiment solves the problem of non-contact vibration signal acquisition for magnetic resonance imaging devices by using a laser vibrometer.

[0021] Step b. Calculate the root mean square value (RMS1) of the vibration signal ①.

[0022] Step c. Use MATLAB, Python, or other software to write a conversion program to convert the vibration signal ① into a sound file; the converted sound file format is WAV, MIDI, MP3, WMA, etc.

[0023] Step d. Place a loudspeaker, a sound pressure level meter, a laser vibrometer, and the object to be tested in a quiet laboratory. Play an audio file using the loudspeaker, measure the sound power level generated by the audio file using the sound pressure level meter, and simultaneously use the laser vibrometer to acquire the vibration signal ② generated by the audio file on the surface of the object to be tested. To obtain the best results, in this embodiment, the relative distances between the sound pressure level meter, the loudspeaker, the object to be tested, and the laser vibrometer should be kept consistent to ensure the measurement effect and avoid inaccurate sound reception due to distance. The quiet laboratory is a laboratory with a relative ambient noise level of 0 dB. The loudspeaker includes, but is not limited to, devices that can play audio files, such as a tape recorder; the sound pressure level meter includes all devices that can measure sound pressure levels; the laser vibrometer is a device that uses lasers for non-contact vibration signal acquisition; the object to be tested is a rigid object with damping and reflectivity, such as a flat steel plate or a hard plastic plate, preferably a flat steel plate.

[0024] Step e. Calculate the root mean square value (RMS2) of the vibration signal ②.

[0025] Step f. Repeatedly change the speaker volume to obtain the root mean square (RMS2) value of the vibration signal ② on the surface of the tested object at different sound power levels. Stop the test when RMS2 matches RMS1. The value corresponding to the sound pressure meter at this time is used as an estimate of the sound power level of the noise generated by the magnetic resonance imaging equipment. The method to determine whether the root mean square values ​​RMS1 and RMS2 of the vibration signal are consistent can be based on the matching of graphs or the matching of values, with the matching of graphs being preferred.

[0026] As described above, this embodiment converts the vibration signal ① generated on the surface of the magnetic resonance imaging (MRI) device during operation into a sound file. By playing this sound file, the noise generated during MRI operation is transferred to a quiet laboratory, solving the problem of not being able to directly measure the sound power level of the operating MRI device. The key to this method lies in finding the vibration signal ② generated at a specific playback volume of the sound file in the quiet laboratory at the vibration target point on the surface of the object being tested. The root mean square (RMS) value 2 calculated from this vibration signal ② is consistent with the RMS1 value of the vibration signal ①. At this point, the sound power level value of the sound pressure meter represents the estimated sound power level of the noise generated by the MRI device during operation. The calculation process is simple and does not involve factors that are difficult to determine, such as surface material and shape. The estimated sound power level is more accurate, providing an effective solution for evaluating the sound power level of noise generated by MRI devices during operation.

Claims

1. A method for estimating the sound power level of operating noise in a magnetic resonance imaging (MRI) device, characterized in that, Includes the following steps: Step a: Use a laser vibrometer to acquire the vibration signal ① generated on the surface of the housing of the magnetic resonance imaging device during operation, and calculate the root mean square value RMS1 of the vibration signal ①; the vibration signal ① is vibration acceleration, vibration velocity or vibration displacement; wherein, the noise power level of the magnetic resonance imaging device cannot be directly measured using a sound pressure meter during operation. Step b: Convert the vibration signal ① into a sound file; Step c: Place a loudspeaker, a sound pressure meter, a laser vibrometer, and the object to be tested in a silent laboratory; play a sound file using the loudspeaker, measure the sound power level generated by the sound file using the sound pressure meter, and simultaneously use the laser vibrometer to obtain the vibration signal ② generated by the sound file on the surface of the object to be tested; calculate the root mean square value (RMS2) of the vibration signal ②. Step d: Change the volume of the loudspeaker multiple times to obtain the root mean square value (RMS2) of the vibration signal ② of the surface of the tested object at different sound power levels. Stop the test when RMS2 is consistent with RMS1. The value corresponding to the sound pressure meter at this time is used as the estimated sound power level of the noise generated when the magnetic resonance imaging equipment is working.

2. The method for estimating the sound power level of operating noise of a magnetic resonance imaging device according to claim 1, characterized in that: In step b, a conversion program is written using MATLAB or Python to convert the vibration signal ① into a sound file; the converted sound file format is WAV, MIDI, MP3 or WMA.

3. The method for estimating the sound power level of operating noise of a magnetic resonance imaging device according to claim 1, characterized in that: In step c, the silent laboratory is a laboratory with a relative ambient noise level of 0dB, the loudspeaker is any device that plays audio files, the sound pressure meter is any device that measures sound pressure level, and the laser vibration meter is a device that uses laser to collect vibration signals in a non-contact manner; the object being measured is a rigid object with damping and reflectivity.

4. The method for estimating the sound power level of operating noise of a magnetic resonance imaging device according to claim 3, characterized in that: The object being tested for vibration includes a flat steel plate or a hard plastic plate.

5. The method for estimating the sound power level of operating noise of a magnetic resonance imaging device according to claim 1, characterized in that: The method for determining whether the root mean square values ​​(RMS1) and RMS2 of the vibration signal are consistent in step d is either the matching of graphs or the matching of numerical values.

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