WO2019205841A1

WO2019205841A1 - Method and system for acquiring respiration information

Info

Publication number: WO2019205841A1
Application number: PCT/CN2019/078848
Authority: WO
Inventors: 杜乙; 周舜; 王若曦
Original assignee: 吴昊; 弓健; 岳海振
Priority date: 2018-04-28
Filing date: 2019-03-20
Publication date: 2019-10-31
Also published as: CN108451532A; CN108451532B

Abstract

A method and system for acquiring respiration information. The method comprises: collecting pressure signals respectively corresponding to multiple different body parts of a target human body according to a pre-set pressure collection manner (S10); performing signal processing on the collected pressure signals and analyzing same to obtain a respiration signal corresponding to the target human body (S20); and acquiring a respiration intensity and respiratory rate corresponding to the target human body according to the obtained respiration signal (S30). By collecting body pressure signals of multiple parts of a human body, more accurate respiration information can be acquired, the accuracy and reliability of respiration information acquisition are improved, and the repeatability of the acquisition of respiration information is further enabled. Using the technical solution of simultaneously collecting superficial pressure information upon respiration of a target human body at multiple points to make correlation analysis in cooperation with human anatomy, personalized respiration information such as a respiration mode and the participation degree of organ muscles of the target human body can be further obtained.

Description

Method and system for acquiring respiratory information

Technical field

The present invention relates to the field of biomedical technology, and in particular, to a method and system for acquiring respiratory information.

Background technique

Breathing is an important physiological process of the human body. Respiratory parameters are an important physiological parameter of clinical monitoring. For example, when a patient has respiratory suffocation or even death, the respiratory suffocation alarm through the monitoring device can prompt the medical staff to pay attention to the patient's condition and avoid delaying the patient's condition. Optimal treatment time; in addition, the precise implementation of medical imaging and radiotherapy often requires the use of patient breathing information, such as 4D CT imaging (4D-CT) and Respiratory-Gated Radiotherapy (Respiratory-Gated Radiotherapy) Etc., and the accurate acquisition of patient breathing information (such as respiratory phase, respiratory cycle, etc.) is an important factor in determining imaging or treatment outcome.

At present, in medical imaging and radiotherapy, the most widely used method for obtaining patient respiratory information is to obtain the fluctuation of the abdomen (or the marker on the abdomen) directly or indirectly (by placing a marker) by optical tracking. Breathing information. The main disadvantages of using this method to obtain patient respiratory information are: when the supine position, the human abdominal muscles and fats move during breathing, the abdominal surface is not flat, and the signal collection method based on the abdominal surface is unstable, and at the same time, individual differences and measurements The problem of position dependence seriously interferes with the accuracy, reliability and repeatability of respiratory information collection.

Summary of the invention

The invention provides a method and a system for acquiring respiratory information, which are used for obtaining respiratory information by collecting the change of body surface pressure caused by muscle movement of multiple parts during human breathing, and improving the accuracy and reliability of respiratory information collection.

The present invention provides a method for acquiring respiratory information, and the method for obtaining the respiratory information includes:

According to the preset pressure collection mode, the pressure signals corresponding to different body parts of the target human body are collected;

Performing signal processing on the collected pressure signal, and analyzing the respiratory signal corresponding to the target human body;

Obtaining a respiratory intensity and a respiratory frequency corresponding to the target human body according to the obtained respiratory signal.

Further, the plurality of different body parts includes:

The back, waist and chest of the target human body.

Further, the preset pressure collection mode includes:

For the pressure signal acquisition of the back and the waist, the following acquisition methods can be used: a pressure sensor is arranged on the back of the target human body, or the wearable pressure sensing device is placed on the target human body, or the target human body is placed on the target with a pressure sensor. Recumbent body board equipment;

For the chest pressure signal acquisition, the following acquisition methods can be used: a pressure sensor is placed on the chest of the target human body, or a wearable pressure sensing device is placed on the target human body.

Further, the signal processing is performed on the collected pressure signal, and the respiratory signal corresponding to the target human body is analyzed, including:

Performing analog-to-digital conversion on the collected pressure signal, and converting the collected dynamic pressure signal into a corresponding digital signal;

The band-pass filter is used to filter the converted digital signal to eliminate low-frequency and high-frequency noise interference, and obtain a respiratory signal corresponding to the target human body.

Further, the acquiring the respiratory intensity and the respiratory frequency corresponding to the target human body according to the obtained respiratory signal, including:

Performing a spectrum analysis on the respiratory signal according to the instantaneous amplitude of the respiratory signal obtained from the obtained respiratory signal to obtain an instantaneous frequency of the respiratory signal;

The instantaneous amplitude and the instantaneous frequency are respectively subjected to filtering processing to obtain a respiratory intensity and a respiratory frequency corresponding to the target human body.

Corresponding to the method for obtaining the breathing information provided by the above embodiment, the embodiment of the present invention further provides a system for acquiring breathing information, where the system for acquiring breathing information includes:

The signal acquisition module is configured to collect pressure signals corresponding to different body parts of the target human body according to a preset pressure collection manner;

a signal processing module, configured to perform signal processing on the collected pressure signal, and analyze and obtain a respiratory signal corresponding to the target human body;

And an information acquiring module, configured to acquire, according to the obtained respiratory signal, a respiratory intensity and a respiratory frequency corresponding to the target human body.

Further, the plurality of different body parts includes:

The back, waist and chest of the target human body.

Further, the preset pressure collection mode includes:

Further, the signal processing module is configured to:

Performing analog-to-digital conversion on the collected pressure signal to convert the collected dynamic pressure signal into a corresponding digital signal;

Further, the information acquisition module is configured to:

In an embodiment of the present invention, acquiring the respiratory intensity and respiratory frequency corresponding to the target human body may also be implemented as:

Obtaining a respiratory intensity and a respiratory frequency corresponding to the target human body according to the obtained respiratory signal. The method and system for acquiring respiratory information of the present invention can achieve the following beneficial effects:

Collecting pressure signals corresponding to different body parts of the target human body according to a preset pressure collection manner; performing signal processing on the collected pressure signals, and analyzing and obtaining a respiratory signal corresponding to the target human body; Breathing signal, obtaining the respiratory intensity and respiratory frequency corresponding to the target human body; having the beneficial effect of acquiring more accurate respiratory information by collecting multiple body surface pressure signals, thereby improving the accuracy and reliability of respiratory information acquisition, Further, the acquisition of respiratory information is further reproducible; in addition, the present application uses multiple points to simultaneously collect surface pressure information of the surface of the target human body breathing, and cooperates with the human anatomy to make a correlation analysis technical solution, which can further obtain the breathing of the target human body. Individualized breathing information such as patterns, organ muscle involvement, etc.

Other features and advantages of the invention will be set forth in the description which follows, The objectives and other advantages of the invention may be realized and obtained in the written description and the appended claims.

The technical solutions of the present invention are further described below through the accompanying drawings and embodiments.

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a In the drawing:

1 is a schematic flow chart of an embodiment of a method for acquiring respiratory information according to the present invention;

2 is a schematic flow chart of an embodiment of step S20 in the embodiment of FIG. 1 in a method for acquiring respiratory information according to the present invention;

3 is a schematic flow chart of an embodiment of step S30 in the embodiment of FIG. 1 in a method for acquiring respiratory information according to the present invention;

4 is a schematic diagram of functional modules of an embodiment of a respiratory information acquisition system of the present invention.

detailed description

The preferred embodiments of the present invention are described with reference to the accompanying drawings, which are intended to illustrate and illustrate the invention.

The invention provides a method and a system for acquiring respiratory information. When the human body breathes, the contraction and relaxation of the lungs are mainly realized by the coordinated movement of multiple muscles around the lungs, especially the muscle groups on both sides of the spine (such as the intercostal space). Muscle, upper and lower serratus, lower back serratus), back muscle group, abdominal muscle group and chest muscle group, etc., and muscle movement will cause changes in body surface pressure, this pressure change can be processed and analyzed after the human body The respiratory information is relevant. Based on the above idea, the method and system for acquiring respiratory information of the present invention acquires respiratory information corresponding to the human body by collecting information on changes in body surface pressure caused by muscle movements of multiple parts (such as the back, chest, and waist) when the human body breathes. Thereby improving the accuracy and reliability of the collection of respiratory information; in addition, the present application uses multiple points to simultaneously collect the surface pressure information of the surface of the target human body breathing, and cooperates with the human anatomy to make a correlation analysis technical solution, which can further obtain the breathing of the target human body. Individualized breathing information such as patterns, organ muscle involvement, etc.

As shown in FIG. 1 , FIG. 1 is a schematic flowchart of an embodiment of a method for acquiring respiratory information according to the present invention; and a method for acquiring respiratory information according to the present invention may be implemented as steps S10-S30 as follows:

Step S10: collecting, according to a preset pressure collection manner, a pressure signal corresponding to each of different body parts of the target human body;

In the embodiment of the present invention, the respiratory information acquisition system (hereinafter referred to as “system”) collects pressure signals of a plurality of different body parts of the target human body according to the type of the pressure sensor adopted according to the preset pressure collection mode. . For example, the pressure signals of the back, waist and chest of the target human body are collected. In the embodiment of the present invention, the pressure sensor provided for the target human body includes but is not limited to: a patch type pressure sensor, that is, can be attached to a corresponding part of the target human body, and the above-mentioned patch type pressure sensor is used together with a fixed device. Fixed, for example, a fixed device such as a mesh body or a strap; or a wearable pressure sensing device; or a reclining plate device with a pressure sensor (such as a plate or a bed).

In a preferred embodiment of the present invention, the system can use the following pressure collection methods to collect pressure signals of different body parts of the target human body:

For the pressure signal acquisition of the back and the waist, the following acquisition methods can be used: a pressure sensor is arranged on the back of the target human body, or the wearable pressure sensing device is placed on the target human body, or the target human body is placed on the target with a pressure sensor. Recumbent body board equipment (eg, board, bed, etc.);

For the chest pressure signal acquisition, the following acquisition method can be adopted: a pressure sensor is arranged on the chest of the target human body, for example, a pressure sensor is attached to the chest of the target human body, and the above-mentioned patch type pressure sensor is matched with a fixed device such as a mesh body or a belt. Fixed at the corresponding position of the human body; or, the wearable pressure sensing device is disposed on the target human body; for example, a vest provided with a pressure sensor or the like.

Step S20, performing signal processing on the collected pressure signal, and analyzing and obtaining a respiratory signal corresponding to the target human body;

According to the collected pressure signal, the system performs analog-to-digital conversion on the pressure signal. For example, a multi-bit analog-to-digital converter of at least 16 bits is used to convert the analog digital signal, and the collected analog pressure signal is converted into a digital signal. And performing signal processing on the converted digital signal, for example, performing smoothing filtering on the digital signal to eliminate noise influence, thereby analyzing and obtaining a breathing signal corresponding to the target human body.

Step S30: Acquire a respiratory intensity and a respiratory frequency corresponding to the target human body according to the obtained respiratory signal.

According to the obtained respiratory signal, the system performs signal processing to obtain waveform data corresponding to the respiratory signal, and according to the waveform data of the respiratory signal, the respiratory intensity and respiratory frequency corresponding to the target human body are obtained. For example, according to the waveform data of the respiratory signal, the peak value and the trough value of the respiratory signal waveform are acquired, and the corresponding respiratory frequency is calculated according to the peak value and the trough value.

In a preferred embodiment of the present invention, as shown in FIG. 2, FIG. 2 is a schematic flow chart of an embodiment of step S20 in the embodiment of FIG. 1 in a method for acquiring respiratory information according to the present invention; In the embodiment, "Step S20, performing signal processing on the collected pressure signal, and analyzing the respiratory signal corresponding to the target human body" may be further implemented as steps S21-S22 described in FIG. 2:

Step S21, performing analog-to-digital conversion on the collected pressure signal, and converting the collected dynamic pressure signal into a corresponding digital signal;

Step S22: Filtering the converted digital signal by using a band pass filter to eliminate low frequency and high frequency noise interference, and obtaining a breathing signal corresponding to the target human body.

In the embodiment of the present invention, the digital signal converted by the collected pressure signal is filtered by a band pass filter to eliminate low frequency and high frequency noise interference, thereby obtaining the processed breathing signal. The passband range of the bandpass filter may be configured according to a clinical or specific application scenario, which is not specifically limited in the embodiment of the present invention. Further, the band pass filter used in the embodiment of the present invention is a digital band pass filter.

In a preferred embodiment of the present invention, as shown in FIG. 3, FIG. 3 is a schematic flowchart of an embodiment of step S30 in the embodiment of FIG. 1 in a method for acquiring respiratory information according to the present invention; In the embodiment, "Step S30, obtaining the respiratory intensity and respiratory frequency corresponding to the target human body according to the obtained respiratory signal" may further be implemented as steps S31-S32 described in FIG. 3:

Step S31, performing spectral analysis on the respiratory signal according to the instantaneous amplitude of the respiratory signal obtained from the obtained respiratory signal, to obtain an instantaneous frequency of the respiratory signal;

Step S32: Perform filtering processing on the instantaneous amplitude and the instantaneous frequency respectively to obtain a respiratory intensity and a respiratory frequency corresponding to the target human body. In the embodiment of the present invention, for the respiratory signal obtained after the noise reduction process, the system acquires the time domain signal and performs spectrum analysis on the time domain signal to obtain the instantaneous amplitude and the instantaneous frequency corresponding to the respiratory signal; as the corresponding instantaneous respiratory intensity And the instantaneous respiratory rate; performing the digital low-pass filtering process on the obtained instantaneous respiratory intensity and the instantaneous respiratory frequency respectively, obtaining an average respiratory intensity and an average respiratory frequency, and obtaining the obtained average respiratory intensity and the average respiratory frequency as the target human body corresponding Respiratory intensity and respiratory rate.

In the embodiment of the present invention, when the obtained instantaneous respiratory intensity and the instantaneous respiratory frequency are digitally low-pass filtered, a signal average filtering technique or an equivalent infinite impulse response low-pass filter is used; those skilled in the art can understand that The above filtering process may also adopt a median equalization filtering technique or a weighted median filtering technique, or a general low-pass filtering technique.

Since the person's speech affects the breathing, it is necessary to remove the part of the signal to make the detection of the respiratory signal more accurate. In an embodiment of the present invention, the pressure signal is also signal processed to obtain the target. The corresponding respiratory signal of the human body:

Identifying a pressure signal period in which the target human body is included in the pressure signal;

Removing the signal of the pressure signal period of the target human body from the pressure signal, and obtaining a pressure signal when the target human body is quiet;

Processing a pressure signal when the target human body is quiet, and obtaining a respiratory signal corresponding to the target human body;

Wherein, the pressure signal period of the target human body included in the pressure signal is identified, specifically:

Selecting the individual's quiet pressure signal and the speech pressure signal for spectrum analysis, and using the spectrum of the pressure signal at rest and the spectrum of the pressure signal during speech as a training set training support vector machine;

The time-frequency analysis of the pressure signal of the target human body is performed to obtain the relationship of the frequency with time, and the result of the time-frequency analysis of the pressure signal is recognized by the support vector machine, and when the pressure signal of a certain period of time is recognized as the pressure when speaking When the signal is used, the time period is used as the pressure signal period of the target human body.

Since different individuals, especially individual body types, have an effect on obtaining respiratory data through pressure data, in order to reduce this effect and improve the accuracy of the acquired respiratory data, in one embodiment of the invention, the target The pressure signal of the human body is processed to obtain the respiratory signal corresponding to the target human body, specifically:

Selecting a static pressure signal of the plurality of individuals and a corresponding respiratory signal measured by the plurality of individuals;

Performing a spectrum analysis on the static pressure signal of each individual to obtain spectral data of the stress signal of each individual at rest;

Cluster analysis is performed on the relationship between the spectral data of the stress signal of each individual's quiet time and the corresponding respiratory signal (such as the ratio of pressure to respiratory intensity), and the relationship between the spectral data of the pressure signal at rest and the corresponding respiratory signal is obtained. Clustering result;

For each classification of the clustering results, the body type (height, waist circumference, fat percentage, etc.) of each individual in the classification is obtained, and the average value of the body type data is taken as the representative value of the body type of the corresponding classification;

Determining the classification to which the target human body belongs according to the similarity between the body shape of the target human body and the body representative value of each classification (such as the weighted average of the height difference, the waist circumference difference, and the fat rate difference);

Perform spectrum analysis on the pressure signal of the target human body at a quiet time, obtain spectrum data of the pressure signal of the target human body, and obtain the target human body according to the relationship between the spectrum data of the pressure signal at the quiet time of the classification of the target human body and the corresponding respiratory signal. Respiratory intensity

The frequency corresponding to the peak value of the amplitude in the spectrum data of the pressure signal of the target human body is taken as the respiratory frequency of the target person.

The method for obtaining respiratory information of the present invention adopts the method according to the preset pressure

Collecting a pressure signal corresponding to a plurality of different body parts of the target human body; performing signal processing on the collected pressure signal, and analyzing the respiratory signal corresponding to the target human body; and obtaining the respiratory signal according to the obtained respiratory signal The respiratory intensity and respiratory rate corresponding to the target human body; the beneficial effects of obtaining more accurate respiratory information by collecting multiple body surface pressure signals, improving the accuracy and reliability of respiratory information acquisition, and further making respiratory information The acquisition is reproducible; in addition, the application uses multiple points to simultaneously collect the surface pressure information of the body surface when the target is breathing, and cooperates with the human anatomy to make a correlation analysis technical solution, which can further obtain the breathing pattern and organ muscle participation of the target human body. Personalized breathing information such as degrees.

Based on a method for acquiring respiratory information described in FIG. 1, FIG. 2 and FIG. 3, the present invention also provides an acquisition system for respiratory information; the acquisition system of the respiratory information can be implemented in FIG. 1, FIG. 2 and FIG. A method for obtaining respiratory information, thereby achieving the purpose of obtaining respiratory information by collecting a change in body surface pressure caused by muscle movement of a plurality of parts during breathing of the human body; as shown in FIG. 4, the present invention provides a respiratory information The acquisition system includes:

The signal acquisition module 100 is configured to collect pressure signals corresponding to different body parts of the target human body according to a preset pressure collection manner;

The signal processing module 200 is configured to perform signal processing on the collected pressure signal, and analyze and obtain a respiratory signal corresponding to the target human body;

The information acquisition module 300 is configured to acquire, according to the obtained respiratory signal, a respiratory intensity and a respiratory frequency corresponding to the target human body.

In a preferred embodiment of the invention, the plurality of different body parts comprises:

The back, waist and chest of the target human body.

In a preferred embodiment of the present invention, the preset pressure collection mode includes:

In a preferred embodiment of the present invention, the signal processing module 200 is configured to:

In a preferred embodiment of the present invention, the information obtaining module 300 is configured to:

The breathing information acquisition system of the present invention collects pressure signals corresponding to different body parts of the target human body according to a preset pressure collecting manner; performs signal processing on the collected pressure signals, and analyzes and obtains breathing corresponding to the target human body. a signal; obtaining a respiratory intensity and a respiratory frequency corresponding to the target human body according to the obtained respiratory signal; and having the beneficial effect of acquiring more accurate respiratory information by collecting multiple body surface pressure signals, thereby improving respiratory information acquisition The accuracy and reliability also make the acquisition of respiratory information reproducible. In addition, the application adopts multiple points to simultaneously collect the surface pressure information of the body surface when the target is breathing, and cooperates with the human anatomy to do the correlation analysis. Individualized breathing information such as respiratory patterns and organ muscle involvement of the target human body can be further obtained.

Those skilled in the art will appreciate that embodiments of the present invention can be provided as a method, system, or computer program product. Thus, the present invention can take the form of an entirely hardware embodiment, an entirely software embodiment, or a combination of software and hardware.

The present invention has been described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (system), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or FIG. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing device to produce a machine for the execution of instructions for execution by a processor of a computer or other programmable data processing device. Means for implementing the functions specified in one or more of the flow or in a block or blocks of the flow chart.

The computer program instructions can also be stored in a computer readable memory that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer readable memory produce an article of manufacture comprising the instruction device. The apparatus implements the functions specified in one or more blocks of a flow or a flow and/or block diagram of the flowchart.

These computer program instructions can also be loaded onto a computer or other programmable data processing device such that a series of operational steps are performed on a computer or other programmable device to produce computer-implemented processing for execution on a computer or other programmable device. The instructions provide steps for implementing the functions specified in one or more of the flow or in a block or blocks of a flow diagram.

It is apparent that those skilled in the art can make various modifications and variations to the invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and modifications of the invention

Claims

A method for obtaining respiratory information, characterized in that the method for obtaining the respiratory information comprises:

According to the preset pressure collection mode, the pressure signals corresponding to different body parts of the target human body are collected;

Performing signal processing on the collected pressure signal, and analyzing the respiratory signal corresponding to the target human body;

Obtaining a respiratory intensity and a respiratory frequency corresponding to the target human body according to the obtained respiratory signal.
The method for obtaining respiratory information according to claim 1, wherein the plurality of different body parts comprises:

The back, waist and chest of the target human body.
The method for acquiring respiratory information according to claim 1 or 2, wherein the preset pressure collection method comprises:

For the pressure signal acquisition of the back and the waist, the following acquisition methods can be used: a pressure sensor is arranged on the back of the target human body, or the wearable pressure sensing device is placed on the target human body, or the target human body is placed on the target with a pressure sensor. Recumbent body board equipment;

For the chest pressure signal acquisition, the following acquisition methods can be used: a pressure sensor is placed on the chest of the target human body, or a wearable pressure sensing device is placed on the target human body.
The method for acquiring respiratory information according to claim 1 or 2, wherein the signal processing of the collected pressure signal is performed to analyze and obtain a respiratory signal corresponding to the target human body, including:

Performing analog-to-digital conversion on the collected pressure signal to convert the collected dynamic pressure signal into a corresponding digital signal;

The band-pass filter is used to filter the converted digital signal to eliminate low-frequency and high-frequency noise interference, and obtain a respiratory signal corresponding to the target human body.
The method for obtaining respiratory information according to claim 1 or 2, wherein the acquiring the respiratory intensity and the respiratory rate corresponding to the target human body according to the obtained respiratory signal comprises:

Performing a spectrum analysis on the respiratory signal according to the instantaneous amplitude of the respiratory signal obtained from the obtained respiratory signal to obtain an instantaneous frequency of the respiratory signal;

The instantaneous amplitude and the instantaneous frequency are respectively subjected to filtering processing to obtain a respiratory intensity and a respiratory frequency corresponding to the target human body.
A system for acquiring respiratory information, characterized in that the system for acquiring respiratory information comprises:

The signal acquisition module is configured to collect pressure signals corresponding to different body parts of the target human body according to a preset pressure collection manner;

a signal processing module, configured to perform signal processing on the collected pressure signal, and analyze and obtain a respiratory signal corresponding to the target human body;

And an information acquiring module, configured to acquire, according to the obtained respiratory signal, a respiratory intensity and a respiratory frequency corresponding to the target human body.
The respiratory information acquisition system of claim 6 wherein said plurality of different body parts comprises:

The back, waist and chest of the target human body.
The system for acquiring respiratory information according to claim 6 or 7, wherein the preset pressure collection method comprises:

For the pressure signal acquisition of the back and the waist, the following acquisition methods can be used: a pressure sensor is arranged on the back of the target human body, or the wearable pressure sensing device is placed on the target human body, or the target human body is placed on the target with a pressure sensor. Recumbent body board equipment;

For the chest pressure signal acquisition, the following acquisition methods can be used: a pressure sensor is placed on the chest of the target human body, or a wearable pressure sensing device is placed on the target human body.
The respiratory information acquisition system according to claim 6 or 7, wherein the signal processing module is configured to:

Performing analog-to-digital conversion on the collected pressure signal, and converting the collected dynamic pressure signal into a corresponding digital signal;

The band-pass filter is used to filter the converted digital signal to eliminate low-frequency and high-frequency noise interference, and obtain a respiratory signal corresponding to the target human body.
The system for acquiring respiratory information according to claim 6 or 7, wherein the information acquisition module is configured to:

Performing a spectrum analysis on the respiratory signal according to the instantaneous amplitude of the respiratory signal obtained from the obtained respiratory signal to obtain an instantaneous frequency of the respiratory signal;

The instantaneous amplitude and the instantaneous frequency are respectively subjected to filtering processing to obtain a respiratory intensity and a respiratory frequency corresponding to the target human body.