A method for measuring water absorbed dose based on ultrasonic temperature measurement technology

Abstract

The present invention discloses a measuring system and method for measuring water absorbed dose based on ultrasonic temperature measurement technology, including a water tank, a magnetic stirring device, a temperature sensor, a data collector and a hydroacoustic transducer, wherein a magnetic stirring device is arranged at the bottom of the water tank, a plurality of temperature sensors are arranged in the water tank to detect the temperature of different areas, the output end of the temperature sensor is connected to the data collector, a radiation source is arranged above the water tank, and the output end of the hydroacoustic transducer is connected to the input end of the ultrasonic signal emission and collection system. Compared with the calorimetric method, the present invention eliminates the non-aqueous materials in the water body membrane to reduce the complexity of the heat exchange problem, the present invention can perform real-time dose measurement, and the measurement process is relatively simple and the measuring device is light.

Description

Technical Field

[0001] The present invention can be applied in the technical field of measuring water absorption dose, and specifically is a measurement method for measuring water absorption dose based on ultrasonic temperature measurement technology. Background Art

[0002] During tumor treatment, clinicians need to know the dose given to the lesion tissue. At the same time, the key link in the radiotherapy process is to control the quality of the radiotherapy equipment. One of the important processes is to measure the output dose of the radiotherapy equipment, that is, the water absorption dose. Therefore, it is very important to use measurement equipment to measure the water absorption dose before radiotherapy.

[0003] The existing methods for measuring water absorption dose mainly include active measurement method and passive measurement method, among which active measurement method mainly includes calorimetry and ionization detection method. Calorimetry mainly uses a calorimeter for measurement, which is composed of a calorimetric core, a water tank, an insulation system, a temperature control system and a back-end readout system. Calorimeters are often used for absolute measurement, and the uncertainty of the measurement results is small, but the whole set of measurement systems is complex, and the device is large and bulky, and the external ambient temperature requirements are extremely high. It is not suitable for clinical quality control measurement, and this method will introduce convection problems of different components and introduce multiple correction factors. The calorimetric core is generally made of graphite material, so the measurement results need to convert the graphite absorption dose into water absorption dose, and further introduce correction factors. The ionization detection method uses a calibrated ionization chamber placed in a water tank for measurement. The main principle of this method is that when the radiation irradiates the detector, it interacts inside the detector and deposits energy. The deposited energy is measured using the basic principle of ionizing radiation, and the water absorption dose is calculated. This measurement method is simple and easy to operate, but it relies on the benchmark or standard of water absorption dose to calibrate it, and the calibration factor can be obtained before the water absorption dose can be measured. The passive measurement method mainly uses thermoluminescence dosimeter or film dosimeter. The passive measurement method means that the measurement result cannot be given in real time during the measurement process, and it needs to be placed on a specific reader for more than 12 hours after irradiation. Thermoluminescence is a device that uses the principle of thermoluminescence to record the cumulative radiation dose. The advantage of this measurement method is that even after being left for a long time, the reading decays very little, and the disadvantage is that it cannot be used for real-time dose measurement. In the same way, the film dosimeter is based on the radiochromic property. When ionizing radiation passes through the film, the chemical substances in the film react chemically, resulting in color changes, which reflects the radiation dose. After the film is irradiated, it takes at least 12 hours to read it. Therefore, it cannot reflect the change of dose value in real time. Therefore, a measurement method based on ultrasonic temperature measurement technology is needed to measure the water absorption dose. Summary of the invention

[0004] The present invention aims to provide a method for measuring water absorbed dose based on ultrasonic temperature measurement technology.

[0005] The present invention specifically comprises the following steps:

[0006] Step 1: Measure the straight-line distance L between the hydroacoustic transducers on both sides of the water tank;

[0007] Step 2: reading the real-time parameters of multiple temperature sensors in the water tank, and quickly transferring the temperature of the water tank through a magnetic stirrer until the water temperatures at different positions in the water tank are the same;

[0008] Step 3: Using ultrasonic phase measurement technology, determine the average sound velocity change caused by temperature by tracking the phase change of the burst tone, operate at a constant frequency, use dual reference ex situ technology to directly detect the phase change caused by temperature, and convert it into flight time The estimated value of the flight path L and flight time The ratio of ), the flight speed v is obtained and the average temperature is calculated as follows:

[0009] (2)

[0010] Where v is the propagation speed in water, in m / s, and a is -0.038 m·s -1 ℃ -2 , b is 4.624 m·s -1 ℃ -1 c is the sound intensity when the temperature is 0℃, and the value is 1405.03m / s;

[0011] Step 4: Turn on the radiation field to irradiate the water tank and measure the flight time again to calculate the irradiation temperature T1 and the temperature difference between the two measurements. ;

[0012] Step 5 Calculate the water absorbed dose based on the temperature change caused by radiation. The calculation formula is:

[0013] (3)

[0014] Where: Cm is the specific heat capacity of water, which is 4.2×103J / (kg·℃); temperature difference is the difference between the irradiation temperature and the average temperature.

[0015] Furthermore, the irradiation time is at least 1 minute.

[0016] In another aspect, a measurement method system for measuring water absorbed dose based on ultrasonic temperature measurement technology is used to perform a measurement method for measuring water absorbed dose based on ultrasonic temperature measurement technology, including a water tank, a magnetic stirring device, a temperature sensor, a data collector and a hydroacoustic transducer. A magnetic stirring device is provided at the bottom of the water tank, and multiple temperature sensors are provided in the water tank to detect the temperature of different areas. The output end of the temperature sensor is connected to the data collector, a radiation source is provided above the water tank, and the output end of the hydroacoustic transducer is connected to the input end of the ultrasonic signal emission and collection system.

[0017] Furthermore, a foam insulation layer is provided on the outside of the water tank.

[0018] Furthermore, the magnetic stirring device comprises a magnetic stirrer and a magnetic stirrer that magnetically repels the magnetic stirrer.

[0019] Furthermore, the hydroacoustic transducer includes a hydroacoustic transducer and a hydroacoustic transducer, and the hydroacoustic transducer and the hydroacoustic transducer are on the same straight line.

[0020] Furthermore, the water tank is made of plexiglass.

[0021] Compared with the prior art, the present invention adopts the above technical solution, and the biggest feature is:

[0022] The present invention obtains the water absorption dose value based on ultrasonic temperature measurement technology, which is completely different from the existing measurement methods. Compared with the calorimetric method, it eliminates non-aqueous materials in the water body membrane to reduce the complexity of the heat exchange problem. Compared with the ionization method, it reduces the calibration process. Compared with the passive dosimeter, the present invention can perform real-time dose measurement, and the measurement process is relatively simple and the measurement device is light. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the measurement system module for measuring water absorbed dose based on ultrasonic temperature measurement technology of the present invention;

[0024] Figure 2 It is a schematic diagram of a measuring system for measuring water absorbed dose based on ultrasonic temperature measurement technology of the present invention;

[0025] Figure 3 It is a connection schematic diagram of the measuring system for measuring water absorbed dose based on ultrasonic temperature measurement technology of the present invention; DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0027] like Figure 1-3 As shown, a measurement system for measuring water absorbed dose based on the ultrasonic velocimetry principle includes a water tank, a magnetic stirring device, a temperature sensor, a data collector and a hydroacoustic transducer. A magnetic stirring device is provided at the bottom of the water tank. A plurality of temperature sensors are provided in the water tank to detect the temperature of different areas. The output end of the temperature sensor is connected to the data collector. A radiation source is provided above the water tank. The output end of the hydroacoustic transducer is connected to the input end of the ultrasonic signal emitting and collecting system.

[0028] A foam insulation layer is arranged on the outside of the water tank.

[0029] The underwater acoustic transducer includes an underwater acoustic transducer 4-1 and an underwater acoustic transducer 4-2. The underwater acoustic transducer 4-1 and the underwater acoustic transducer 4-2 are on the same straight line and have parallel surfaces.

[0030] The magnetic stirrer 1 utilizes the principle that like charges repel and opposite charges attract in a magnetic field, and uses the magnetic field to drive a magnetic stirrer 2 placed in a solution to perform a circular motion, thereby achieving the purpose of stirring the liquid.

[0031] The organic glass water tank 3 is composed of 6 organic glass panels, the thickness of the organic glass is 11 mm, and the side length is 300 mm. The top organic glass 3-1 can be freely disassembled, and three holes are evenly distributed on the diagonal line of the organic glass panel 3-1. The remaining surfaces 3-2, 3-3, 3-4, 3-5, and 3-6 are bonded by glue or other methods to form a water tank.

[0032] The underwater acoustic transducer 4 is composed of two transducers. The underwater acoustic transducer 4-1 is installed on the organic glass plate 3-3 on the side of the organic glass water tank 3, and the underwater acoustic transducer 4-2 is installed on the organic glass plate 3-4 on the side of the organic glass water tank 3. The orientations of the two transducers are adjusted so that the two transducers are on the same straight line and the surfaces are parallel. The pulse frequency used by the underwater acoustic transducer is 5MHz, and it has a waterproof function and can work underwater. The underwater acoustic transducer 4-1 is a signal-emitting transducer, and the emitted signal is received by the underwater acoustic transducer 4-2 after being propagated through the water medium.

[0033] The heat-insulating foam box 5 surrounds the organic glass water tank 3 and is made of polypropylene, which has excellent heat-insulating and environmentally friendly properties, is durable, easy to process, and does not release harmful gases at high temperatures. The thickness of the heat-insulating foam box 5 is 10 cm, which mainly plays a good role in heat-insulating properties.

[0034] The temperature sensor 6 is composed of a platinum resistance probe, and a stainless steel tube is used to encapsulate the platinum resistance element. When the temperature changes, the resistance value of the resistor increases. The temperature value is measured by the back-end data collector 7 based on the relationship between resistance and temperature. The temperature transmitter has three probes, namely temperature sensors 6-1, 6-2 and 6-3, which are inserted into the water tank through the holes of the organic glass 3-1 to measure the temperature in the water tank at different positions.

[0035] The data collector 7 is mainly used to collect data from the temperature sensor 6, and after amplification and filtering, the temperature value is measured. The present invention uses the DAQ970A data collector of the Keysight brand, which can accurately collect the temperature value. It has the characteristics of high measurement accuracy and stable performance.

[0036] The ultrasonic signal sending and collecting system 8 is a self-designed collection system, which is connected to the underwater acoustic transducer 4-1 and the underwater acoustic transducer 4-2 through a signal line. The ultrasonic signal sending and collecting system 8 performs signal excitation through the underwater acoustic transducer 4-1, collects the signal of the underwater acoustic transducer 4-2 after filtering and analysis, and calculates the ultrasonic flight time.

[0037] Temperature changes affect the propagation of sound waves in the medium, and the waves are very sensitive to temperature changes. In water, under constant atmospheric pressure and impurity concentration, the speed of sound depends only on temperature and can be approximated by the empirical formula (1).

[0038] (1)

[0039] Where v is the propagation speed in water, in m / s. , a is -0.038 m·s -1 ℃ -2 , b is 4.624 m·s -1 ℃ -1 c is the sound intensity when the temperature is 0℃, and its value is 1405.03m / s.

[0040] When liquid water is exposed to radiation, the temperature of the water changes, which affects the propagation speed of ultrasound in the water. From a single ultrasound flight time and phase measurement, the average sound speed v along the acoustic path can be obtained, and the temperature distribution along the path can be obtained by solving equation (1). For very small temperature gradients in undisturbed water, the acoustic path can be accurately approximated as a straight line between the water tank walls.

[0041] The central problem of the measurement is to determine the average sound velocity change caused by temperature by tracking the phase change of the burst tone using ultrasonic phase measurement technology, working at a constant frequency, using a dual reference ex situ technique to directly detect the phase change caused by temperature and convert it into flight time. According to the flight path L and flight time The ratio of ), obtain the flight speed v and calculate the average temperature T.

[0042] (2)

[0043] Measure the temperature before irradiation T0 and the temperature after irradiation T1 to get the temperature change .

[0044] The water absorbed dose is then calculated according to formula (3).

[0045] (3)

[0046] Where: Cm is the specific heat capacity of water, which is 4.2×103J / (kg·℃); is the temperature change caused by radiation, in °C.

[0047] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for measuring water absorbed dose based on ultrasonic temperature measurement technology, characterized in that: The specific steps include: Step 1: Measure the straight-line distance L between the hydroacoustic transducers on both sides of the water tank; Step 2: reading the real-time parameters of multiple temperature sensors in the water tank, and quickly transferring the temperature of the water tank through a magnetic stirrer until the water temperatures at different positions in the water tank are the same; Step 3: Using ultrasonic phase measurement technology, determine the average sound velocity change caused by temperature by tracking the phase change of the burst tone, operate at a constant frequency, use dual reference ex situ technology to directly detect the phase change caused by temperature, and convert it into flight time The estimated value of the flight path L and flight time The ratio of the flight speed v is obtained and the average temperature is calculated as follows: （2） Where v is the propagation speed in water, in m / s, and a is -0.038 m·s -1 ℃ -2 , b is 4.624 m·s -1 ℃ -1 , c is the speed of sound when the temperature is 0℃, and its value is 1405.03m / s; Step 4: Turn on the radiation field to irradiate the water tank and measure the flight time again to calculate the irradiation temperature T1 and the temperature difference between the two measurements. ; Step 5 Calculate the water absorbed dose based on the temperature change caused by radiation. The calculation formula is: （3） Where: Cm is the specific heat capacity of water, which is 4.2×103J / (kg·℃); temperature difference is the difference between the irradiated temperature and the average temperature.

2. The method for measuring water absorbed dose based on ultrasonic temperature measurement technology according to claim 1 is characterized in that: The irradiation time is at least 1 minute.

3. A measurement system for measuring water absorbed dose based on ultrasonic temperature measurement technology, used to implement a measurement method for measuring water absorbed dose based on ultrasonic temperature measurement technology as described in any one of claims 1-2, characterized in that: It includes a water tank, a magnetic stirring device, a temperature sensor, a data collector and an underwater acoustic transducer. The magnetic stirring device is arranged at the bottom of the water tank. A plurality of temperature sensors are arranged in the water tank to detect the temperature of different areas. The output end of the temperature sensor is connected to the data collector. A radiation source is arranged above the water tank. The output end of the underwater acoustic transducer is connected to the input end of the ultrasonic signal emission and collection system.

4. A measurement system for measuring water absorbed dose based on ultrasonic temperature measurement technology according to claim 3, characterized in that: A foam insulation layer is arranged on the outside of the water tank.

5. The measurement system for measuring water absorbed dose based on ultrasonic temperature measurement technology according to claim 3 is characterized in that: The magnetic stirring device comprises a magnetic stirrer and a magnetic stirring bar which magnetically repels the magnetic stirrer.

6. A measurement system for measuring water absorbed dose based on ultrasonic temperature measurement technology according to claim 3, characterized in that: The hydroacoustic transducer comprises a hydroacoustic transducer and a hydroacoustic transducer, the hydroacoustic transducer and the hydroacoustic transducer are on the same straight line, and the surface of the transducer is perpendicular to the central axis.

7. A measurement system for measuring water absorbed dose based on ultrasonic temperature measurement technology according to claim 3, characterized in that: The water tank is made of plexiglass.

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