KR101330117B1 - Positron emission tomography scanner with multi-channel photo-sensor and gamma-ray energy - Google Patents

Abstract

The present invention relates to a positron emission tomography scanning device using a multi-channel photoelectric device comprising multiple photoelectric devices converting an optical signal, which is corresponding to an incident first gamma ray, into an electrical signal by being formed of m x n matrix form wherein multiple photoelectric devices are connected to each row signal line by having the photoelectric devices of the same row to be mutually connected; converting the photoelectric device output of the multi-channel photoelectric device part of a first radiation detector connected to each heat signal line into a digital signal through multiple comparators before outputting by controlling the photoelectric devices of the same column to be mutually connected; measuring first through fourth absolute times from the digital signal for measuring energy using the first and second absolute times and grasping the difference between incident times corresponding to two gamma ray using the third absolute time. [Reference numerals] (310) First comparison unit;(320) Second comparison unit;(410) First measurement unit;(420) Second measurement unit;(510) First information processing unit;(520) Second information processing unit;(600) Effectiveness determination unit

Description

Positron emission tomography scanner with multi-channel photo-sensor and gamma-ray energy

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Positron Emission Tomography (PET) scanner. In particular, an incident incident on two photoelectric devices corresponding to a pair of gamma rays and energy of gamma rays through abbreviated signal lines of a multichannel photoelectric device A positron emission tomography apparatus for measuring a difference in time information.

In general, a positron emission tomography apparatus diagnoses a cancer or brain lesion using a radioisotope emitter that emits positrons, and collects two gamma rays generated from the lesion to image the location of the lesion in three dimensions. The two gamma rays generated at this time are generated at an angle of 180 degrees with each other due to the characteristics of the generation.

In the conventional positron emission tomography apparatus, only two gamma ray detections are detected within a predetermined time range and stored as one data when this condition is satisfied. However, since only the occurrence was recorded, it was not possible to deduce exactly where a gamma ray was emitted from a single occurrence.

Gamma rays are a kind of electromagnetic waves, and both gamma rays have the same speed of light. If a measurement system capable of measuring the propagation velocity according to the speed of light is applied to the positron emission tomography system, the generation position can be inferred by the time difference between the gamma rays reaching the two gamma ray detectors. Nuclear medicine imaging equipment using this principle is called time-of-flight PET (TOF-PET).

In order to distinguish the difference in the time that gamma rays reach, a high speed photoelectric device is required in which signal generation and destruction are high speed.

However, in accordance with the development of technology, in the development of PET detectors, the ratio of scintillation crystal area is getting smaller due to the miniaturization of the photosensitive area of the photoelectric device. As a result, in order to control each photoelectric device or to process signals obtained from the photoelectric device, The additional circuits required have increased dramatically. Until now, due to technical limitations, a good time resolution can be obtained only by reading the time information directly from the optoelectronic device without signal reduction.

As a method of measuring energy, there is a method of quantifying the charge amount of a signal to be measured for a predetermined time, and storing the energy of the signal by recording the waveform of the signal through an analog-to-digital converter (ADC). There is this.

However, the first method requires precise analog devices and there are technical and spatial problems to make them multi-channel. The second method is currently widely used, and can simultaneously perform waveform analysis.

When the time of arrival of a signal, such as a TOF PET detector, must be recorded together, there is a difference in processing time because the implementation of the part for measuring time and the part for calculating energy and position are different. Therefore, an additional circuit is required to match the concurrency of each calculation result, but the circuit to match the difference in processing time increases the complexity of the overall circuit, thereby increasing the complexity of the system.

Therefore, there is a need for a method capable of using a multichannel photosensitive device (i.e., a multichannel optoelectronic device) having a small photosensitive area in a TOF-PET.

The technical problem of the present invention is to shorten each photoelectric device of a multi-channel photoelectric device according to a rule, and to measure the time difference between two received gamma rays, as well as to measure the width of a signal with the same module, The present invention provides a positron emission tomography apparatus using a multichannel optoelectronic device capable of measuring energy.

According to one aspect of the present invention to achieve the above object, there is provided a positron emission tomography apparatus using a multi-channel optoelectronic device. The positron emission tomography apparatus using the multichannel optoelectronic device includes a plurality of optoelectronic devices converting an optical signal corresponding to the incident first gamma ray into an electrical signal and configured in a matrix of rows x columns (mxn). The multi-channel optoelectronic device portion of the first radiation detector is a plurality of optoelectronic devices are connected to each other in the row of the photoelectric elements of the same row are connected to each row signal line, and the optoelectronic devices of the same column are connected to each column signal line, At least m connected to each of the m row signal lines connected to an output terminal of the channel photoelectric device unit to receive the output of the photoelectric device, and convert the output of the photovoltaic device into a first digital signal by comparing with the first set voltage; A first comparator including four comparators, one each connected to n column signal lines connected to an output terminal of the multi-channel A second comparator comprising at least n comparators for receiving an output of the photoelectric device and comparing the output of the photoelectric device with a second set voltage to form a second digital signal and outputting the second digital signal; A first measuring unit connected to a comparator, the first measuring unit including at least m measuring units measuring the first absolute time at the rising edge of the first digital signal and the second absolute time at the falling edge of the first digital signal, and each comparator of the second comparing unit A second measuring unit connected to each of the second measuring unit, the second measuring unit including at least n measuring units measuring a third absolute time of the rising edge point and a fourth absolute time of the falling edge point of the second digital signal, and the measuring unit of the first measuring unit The received first and second absolute times are transmitted as energy measurement information, and the third absolute time received from the measuring unit of the second measuring unit is a precise time. It includes an information management unit for transmitting the information for measuring the difference.

The optoelectronic device may be a semiconductor-based optoelectronic device or a photomultiplier tube (PMT). The semiconductor-based photoelectric device is one of silicon photomultiplier (SiPM) or Avalanche photo diode (APD).

Each of the plurality of optoelectronic devices may output the electrical signal to each of the row signal line and the column signal line in response to an incident optical signal. The first set voltage of the first comparator is a voltage that determines a width of the signal in proportion to the energy of the received signal. The second set voltage of the second comparator may be set equal to or lower than the first set voltage.

Each measuring unit of the at least first measuring unit may invalidate the received first digital signal if the length of the time indicating the value of 1 from the first digital signal is less than the set time.

According to an embodiment of the present invention, while applying a signal reduction technique, it is possible to obtain precise time resolution and obtain the generation position, energy and time information of the gamma ray only by time measurement.

In addition, according to an embodiment of the present invention it is possible to obtain the effect of reducing the spatial and technical complexity. In addition, according to an embodiment of the present invention to become the basis of the multi-channel processing technology required for the development of whole-body PET, and to enable the time measurement to the PET / MR (Magnetic Resonance) simultaneous image acquisition device developed using a semiconductor optoelectronic device Extended application is possible.

1 is a main configuration diagram of a positron emission tomography apparatus using a multi-channel photoelectric device according to an embodiment of the present invention.
2 is a block diagram of a positron emission tomography apparatus using a multi-channel photoelectric device according to the first embodiment of the present invention.
3 is a view illustrating an operation of each amplification unit according to an embodiment of the present invention.
4 is a view for explaining the operation of each measurement unit according to an embodiment of the present invention.
5 is a flowchart illustrating an operation of a positron emission tomography apparatus using a multi-channel photoelectric device according to an exemplary embodiment of the present invention.
6 is a block diagram of a positron emission tomography apparatus using a multi-channel optoelectronic device according to a second embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Referring now to the drawings, a positron emission tomography apparatus using a multichannel optoelectronic device according to an embodiment of the present invention will be described in detail.

1 is a main configuration diagram of a positron emission tomography apparatus using a multi-channel photoelectric device according to an embodiment of the present invention. As shown in FIG. 1, a positron emission tomography apparatus using a multi-channel photoelectric device according to an exemplary embodiment of the present invention may include a radiation detector 10, first and second comparators 310 and 320, and first and second sources. 2 includes a measuring unit 410, 420, information management unit 500 and the validity determination unit 600.

The radiation detector 10 is composed of a plurality of radiation detectors. In FIG. 1, although the plurality of radiation detectors are illustrated as forming an octagonal shape, various forms are possible without being limited thereto.

Each radiation detector constitutes an optoelectronic device that converts gamma rays into an electrical signal. The optoelectronic device is, for example, a semiconductor-based optoelectronic device, a photomultiplier tube (PMT), and is formed in a matrix to form a multichannel optoelectronic device. do.

In this case, the matrix form includes photoelectric elements in an array form or single elements in an array form. The semiconductor-based optoelectronic device may be, for example, a silicon photomultiplier (SiPM) or an avalanche photo diode (APD).

On the other hand, the positron emission tomography apparatus according to an embodiment of the present invention diagnoses a lesion of cancer or brain using a radioisotope tracer that emits a positron, and collects two gamma rays generated from the lesion to determine the location of the lesion. In the three-dimensional imaging, the two gamma rays generated are generated at an angle of 180 degrees with respect to the characteristics of the generation.

Therefore, since two gamma rays generated at the body part are formed at an angle of 180 degrees, they are detected in a specific photoelectric device of each of the two radiation detectors set in pairs. That is, the photoelectric element at a specific position in the first radiation detector is set to correspond to another photoelectric element at a specific position in the second radiation detector, so that the positron emission tomography apparatus has a photoelectric at a specific position in the two corresponding radiation detectors. The information output from the device is recognized as information on two gamma rays generated at the same site.

Hereinafter, an embodiment of the present invention will be described with reference to a multi-channel photoelectric device unit in one radiation detector for clarity.

In the multi-channel optoelectronic device according to an embodiment of the present invention, the signal generated by each optoelectronic device is divided into two outputs. At this time, one output (hereinafter referred to as "first output") is for detecting the magnitude of energy, the other output (hereinafter referred to as "second output") is for detecting the incident time information. Here, the first output and the second output of each photoelectric element are analog signals.

The first comparator 310 receives a first output output from the optoelectronic device, and compares the first output with the first set voltage to detect the energy of the first output and corresponds to the energy of the first output. Output a digital signal. In this case, the first digital signal represents a section higher than the first set voltage as a value of 1 at a first output, a section lower than the first set voltage as a value of 0, and represents a shape of a square wave as a whole.

The second comparator 320 receives the second output output from the photoelectric device, and compares the second output with the second set voltage to correspond to the incident time of the second output to detect the incident time information of the second output. Outputs a second digital signal. In this case, the first digital signal represents a section higher than the first set voltage as a value of 1 at a first output, a section lower than the first set voltage as a value of 0, and represents a shape of a square wave as a whole.

The first measuring unit 410 is connected to the first comparator 310, and grasps a time (hereinafter, referred to as “first absolute time”) changed from a value of 0 to a value of 1 from the first digital signal. Determine the time of change from the value of 1 to the value of 0 (hereinafter referred to as "second absolute time"). In addition, the second measurement unit 420 is connected to the second comparison unit 320, and grasps the time (hereinafter referred to as “third absolute time”) changed from a value of 0 to a value of 1 from the second digital signal. , The time of change from the value of 1 to the value of 0 (hereinafter referred to as "fourth absolute time").

Here, since the first and second digital signals represent the shape of a square wave, the time when the value is changed from a value of 0 to a value of 1 is a time of a rising edge signalically, and a time when the value is changed from a value of 1 to a value of 0. Is signal time of the falling edge.

The information manager 500 uses the first and second absolute times output from the first measuring unit 410 and the width between the absolute times using one of the third and fourth absolute times output from the second measuring unit 420. (I.e. the length of time), the time of incidence using the other, and the time information thus rearranged into the energy measurement information and the precision time difference measurement information, respectively, and the following configuration (i.e., the validity judgment unit) (600).

That is, the information management unit 500 receives the first and second absolute times output from the first measurement unit 410 and processes (ie, rearranges) the energy processing information (ie, rearrangement), and And a second information processing unit 520 which receives the third and fourth absolute times output from the second measuring unit 420 and processes (ie, rearranges) the data into precision time difference measurement information.

The validity judgment unit 600 receives the energy measurement information (ie, the first and second absolute time) and the precise time difference measurement information (including at least the third absolute time information) provided by the information manager 500. In addition, it receives energy measurement information, precision absolute time information, and precision time difference measurement information on the output of each photoelectric device provided by another radiation detector. In addition, the validity determination unit 600 compares the precision time difference measurement information with the set reference time to effectively process or invalidate the output of the photoelectric device. In addition, the validity determination unit 600 separates the event through the difference of the absolute time information on the output of the photovoltaic device effectively processed when multiple events occur.

Hereinafter, each configuration of the positron emission tomography apparatus using the multichannel optoelectronic device according to the first embodiment of the present invention will be described in detail with reference to FIGS. 2 to 4. FIG. 2 is a block diagram of a positron emission tomography apparatus using a multi-channel photoelectric device according to a first embodiment of the present invention.

As shown in FIG. 2, the positron emission tomography apparatus using the multichannel optoelectronic device according to the first exemplary embodiment of the present invention includes a multichannel optoelectronic device 100, a first amplifier 210, and a second amplifier. 220, a first comparator 310, a second comparator 320, a first measurer 410, a second measurer 420, and an information manager 500.

The multi-channel optoelectronic device portion 100 includes a plurality of optoelectronic devices 110 for converting the received optical signal into an electrical signal, each optoelectronic device 110 is a photomultiplier tube (PMT) or a semiconductor-based optoelectronic device, for example It may be a silicon photomultiplier tube (SiPM) or an Avalanche photo diode (APD).

Each photoelectric device 110 is arranged in a matrix form of rows x columns (m x n), the photoelectric elements of the same row are connected to each other, the photoelectric elements of the same column are connected. That is, n photoelectric elements forming one row are connected to each other, and n photoelectric elements forming each remaining row (2, 3, ..., m rows) also have the same connection structure. In other words, m photoelectric elements forming one row are connected to each other, and m photovoltaic elements forming the remaining columns (2, 3, ..., n columns) also have the same connection structure.

At this time, m and n may be the same or different, and the number varies depending on the configuration of the system or the characteristics of the device. Due to the nature of nuclear medical imaging devices, increasing the size of m and n can cause different simultaneous events to occur within very short time intervals. It is possible to distinguish the comparison with respect to the incident time).

On the other hand, the output terminals of the photoelectric elements grouped in rows are connected to one row signal line, and the photoelectric elements in the same row output the photoelectrically converted signals to the same row signal line. For example, the first row is connected to the first row signal line, the second row is connected to the second row signal line, the photovoltaic elements of the first row transmit output to the first row signal line, and the photovoltaic elements of the second row The output is sent to the second row signal line.

The output terminals of the photoelectric elements, which are bundled in columns, are connected to one column signal line, and the photoelectric elements of the same column output a photoelectric conversion signal to the same column signal line. For example, the first column is connected to the first column signal line, the second column is connected to the second column signal line, the photoelectric elements in the first column transmit the output to the first column signal line, and the photoelectric elements in the second column are connected to the second column signal line. The output is sent to the thermal signal line.

According to the connection structure of the rows and columns of each photoelectric device, the conventional (m x n) signal lines are reduced to (m + n).

Therefore, the position detected when one event occurs in the detector having the sizes m and n may be defined as the intersection of the row where the row signal is generated and the column where the column signal is generated. If different events occur within a very short time interval, the two events can be separated or sometimes invalidated based on the absolute time measured in the rows and columns.

The first amplifier 210 includes m amplifiers 211, and each amplifier 211 is connected to a photoelectric device forming a row in the multi-channel photoelectric device unit 100 through each row signal line. For example, the photoelectric devices 110 in one row are connected to the first amplifier 211 through the first row signal line, and the photoelectric devices 110 in two rows are connected to the second amplifier 211 through the second row signal line. To achieve. Therefore, the first amplifier 210 amplifies and outputs the signal output from the photoelectric device 110 at the row side of the multi-channel photoelectric device unit 100 by a set gain.

The second amplifier 220 includes n amplifiers 221, and each amplifier 221 is connected to an optoelectronic device forming a column in the multi-channel optoelectronic device 100 through each column signal line. For example, the photoelectric devices 110 in one row are connected to the first amplifier 221 through the first column signal line, and the photoelectric devices 110 in two rows are connected to the second amplifier 221 through the second column signal line. . Therefore, the second amplifier 220 amplifies and outputs a signal output from the photoelectric device 110 on the column side of the multi-channel photoelectric device unit 100 by a set gain.

Meanwhile, at least one of each of the amplifiers 211 and 221 constituting the first and second amplifiers 210 and 220 may be adjusted to amplification ratio or the number of stages, or may be configured as an inverting and non-inverting amplifier stage. .

3, the signals output from the amplifiers 211 and 221 of the first amplifier 210 and the second amplifier 220 will be described with reference to FIG. 3. 3 is a view illustrating an operation of each amplification unit according to an embodiment of the present invention.

As shown in FIG. 3, when each amplifier 211 of the first amplifier 210 receives the output of the photoelectric device 110 through the row signal line, the output of the photoelectric device 110 (analog signal) as in g1. Amplify the output. In addition, when the amplifier 221 of the second amplifier 220 receives the output of the optoelectronic device 110 through the thermal signal line, amplifies and outputs the output (analog signal) of the optoelectronic device 110 as in g2. On the other hand, each of the amplifiers (211, 221) is preferably to use a minimum of a single circuit to prevent the loss of time information of the signal. In addition, the amplification ratios of the first amplification unit and the second amplification unit may vary according to the characteristics and the use of the device.

The first comparator 310 includes at least m comparators 311, and each of the comparators 311 receives an output of the photoelectric device 110 amplified from one corresponding amplifier 211. The second comparator 320 includes at least n comparators 321, and each of the comparators 311 receives an output of the photoelectric device 110 amplified from one corresponding amplifier 221.

Each of the comparators 311 and 321 of the first and second comparators 310 and 320 compares the outputs of the received amplifiers 211 and 221 with the set voltage, when the output is applied above the set voltage. It is a digital circuit that outputs a value of "1" during the time and outputs a value of "0" during that time when the output is applied below the set voltage.

In this case, the set voltages of the first and second comparators 310 and 320 are classified according to the role of the row signal (eg g1) and the column signal (eg g2) output from the multi-channel optoelectronic device unit 100.

If the row signal is set as a role for measuring energy, the set voltage set in each of the comparators 311 of the first comparator 310 is determined by OT emission time tomography using a time over threshold (TOT) method. The energy of 511-keV to be used is set well enough to distinguish and measure.

In general, the signal output from the photoelectric device 110 has a section in which the width of the signal is proportional to the energy of the signal of interest, and at this time, the voltage for determining the width of the signal in proportion to the energy is set as the set voltage of the comparator 311. do.

Accordingly, the comparator 311 outputs a first digital signal indicating a value of 1 when the signal g1 of the amplifier 211 is greater than or equal to the set voltage, and a value of 0 when less than the set voltage, as shown by g3 of FIG. 4, The first digital signal is output in the form of a square wave. In FIG. 4, P1 is time information in a section in which the signal of the amplifier 211 is greater than or equal to the set voltage.

When the thermal signal is set as a role for measuring the precise time difference, the set voltage set in each comparator 321 of the second comparator 320 is a set voltage for measuring energy (the set voltage of the first comparator). It can be set equal to or lower than) and depends on the characteristics of the optoelectronic device used. This is because the time difference measurement result is good for detecting the first or second photons arriving at the photoelectric device in order to accurately determine the time difference caused by a pair of gamma rays.

Therefore, the comparator 321 outputs a second digital signal indicating a value of 1 when the signal g2 of the amplifier 221 is greater than or equal to the set voltage and a value of 0 when less than the set voltage, as shown by g4 of FIG. 4, The second digital signal is output in the form of a square wave.

On the other hand, it is possible to set the roles of the output of the row signal line and the output of the column signal line with each other, and in this case, it is achieved by changing the set voltages of the comparators 311 and 321. Each comparator 311 and 321 may have an interface output capable of high speed transmission.

The first measuring unit 410 includes at least m measuring devices 411, and each measuring device 411 receives the first digital signal from one corresponding comparator 311. In addition, each measuring device 411 determines the absolute time of the rising edge, that is, the first absolute time T1 and the absolute time of the falling edge, that is, the second absolute time T2, in the received first digital signal (FIG. 3). Reference).

The second measuring unit 420 includes at least n measuring units 421, and each measuring unit 421 receives a second digital signal from one corresponding comparator 321. Each measuring unit 421 determines the absolute time of the rising edge, that is, the third absolute time T3 and the absolute time of the falling edge, that is, the fourth absolute time T4, from the received second digital signal (FIG. 3). Reference).

If the second measurement unit 420 serves as a precise time measurement, the third absolute time T3 measured by the second measurement unit 420 may be equal to the third absolute time measured from another detector set as a pair. The difference is judged as the time difference between two incident gamma rays.

When the first measuring unit 410 serves as an energy measuring device, the time lengths P1 of the first and second absolute times T1 and T2 measured by the first measuring unit 410 are measured and measured. The magnitude of the energy corresponding to the time length P1 is determined.

When the first information processing unit 510 of the information management unit 500 is in charge of energy measurement information processing, the first and second absolute times output from the first measurement unit 410 are received as energy measurement information. Processing (that is, repositioning), and the second information processing unit 520 receives the third and fourth absolute times output from the second measuring unit 420, and processes the processing (that is, repositioning) the information for precise time difference measurement. ) do.

On the other hand, the first embodiment of the present invention described above is for the case where the output of the multichannel optoelectronic device portion 100 is not large enough, and in the case where the output of each photoelectric device of the multichannel optoelectronic device portion 100 is sufficiently large. The first and second amplifiers 210 and 220 may be omitted.

On the other hand, the validity determination unit 600 is used to determine the validity of the signal generated in the corresponding time length (P1). When the set voltage of the second comparator 321 is lower than that of the first comparator 311, the time length of the output signal of the second comparator 321 is the width by the first comparator 311 (that is, the length of time P1). Must be longer than) to be a valid signal. This is used as data to prevent erroneous detection by noise that may occur when the set voltage of the second comparator 321 is low.

In addition, at least one of the validity determining unit 600 or the first and second measuring units 410 and 420, which measures at least one of the energy measurements, is present when the measured length of 1 is shorter than the set time. The measurement result is considered invalid.

Hereinafter, the operation of the positron emission tomography apparatus using the multi-channel photoelectric device according to the first embodiment of the present invention configured as described above will be described with reference to FIG. 5.

FIG. 5 is a flowchart illustrating an operation of a positron emission tomography apparatus using a multi-channel photoelectric device according to an exemplary embodiment of the present invention, which measures energy through a row signal line and precise time measurement through a column signal.

A positron emission tomography apparatus irradiates gamma rays to a patient and receives two gamma rays emitted at an angle of 180 degrees from the patient, respectively, at two radiation detectors.

The gamma rays received by each of the two radiation detectors are incident on one photoelectric device 110 corresponding to the generated position among the plurality of photoelectric devices constituting the multichannel photoelectric device unit 100 (S501), and the photoelectric device 110. By converting into an electrical signal by the output (S502).

In this case, one photoelectric device 110 outputs an analog electric signal through the row signal line and the column signal line.

The output of the photoelectric device 110 transmitted through the row signal line is provided to one amplifier 211 connected to the corresponding signal line among the amplifiers 211 of the first amplifier 210, and amplified by the amplifier 211. Is transmitted to the comparator 311 (S503).

The amplified signal is received by a corresponding comparator 311 among the comparators 311 of the first comparator 310, and the comparator 311 compares the amplified signal with a first set voltage (set voltage for energy measurement), A first digital signal having a value of 1 for a signal that is greater than or equal to the first set voltage and a value of 0 for a signal that is less than the set voltage is transmitted to one measuring device 411 (S504).

The first digital signal output from the comparator 311 is received by the corresponding measuring unit 411 of the measuring unit 411 of the measuring unit 410, and the measuring unit 411 receives the first and second absolute times ( T1 and T2) are measured (S505).

Of course, in step S505, the measuring unit 411 obtains the length P1 of the first and second absolute times T1 and T2 and invalidates the received signal when the length P1 is shorter than the set time. It may be (S506).

The first and second absolute times T1 and T2 measured by the measuring device 411 are received by the first information processor 510, and the first information processor 510 transmits the received information to the corresponding optoelectronic device 110. The energy grading information for the display (ie, arrangement) is provided to the validity determining unit 600 (S507).

On the other hand, the output of the photoelectric device 110 transmitted through the thermal signal line is provided to one amplifier 221 connected to the corresponding signal line of the amplifier 221 of the second amplifier 220, amplified by the amplifier 221 And a single comparator 321 is transmitted (S508).

The amplified signal is received by the corresponding comparator 321 among the comparators 321 of the second comparator 320, and the comparator 321 compares the amplified signal with a second set voltage (a set voltage for precision time measurement). In operation S509, a second digital signal indicating a value of 1 for a signal that is greater than or equal to the second set voltage and a value of 0 for a signal that is less than the set voltage is transmitted to one measuring device 411.

The digital signal output from the comparator 321 is received by the corresponding measuring unit 421 of the measuring unit 421 of the measuring unit 420, and the measuring unit 421 receives the third and fourth absolute times (the second and second absolute times) from the received second digital signal. T3 and T4) are measured (S510).

The third and fourth absolute times T3 and T4 measured by the measuring device 421 are received by the second information processor 520, and the second information processor 520 transmits the received information to the corresponding optoelectronic device 110. The information is displayed (ie, arranged) as the precision time measurement for and provided to the validity determining unit 600 (S511).

In addition, the first information processor 510 receives the third and fourth absolute times T3 and T4 from the plurality of measuring devices 311. In this case, each of the information T3 and T4 and the corresponding photoelectric device ( The identification information of the 110 is matched and then provided to the validity determining unit 600. Of course, only the third absolute time T3 may be used to measure the precise time difference. Therefore, the first information processor 510 may provide only the information about the third absolute time T3 to the validity determiner 600.

The validity determination unit 600 collects a signal that processes the output of the multi-channel photoelectric device of one radiation detector and a signal that processes the output of the multi-channel photoelectric device of all other radiation detectors. The validity determination unit 600 corresponds to a pair of information of each third absolute time T3 corresponding to an output of two photoelectric elements (included in different radiation detectors) that detect the gamma ray pair, and correspondingly. In response to the optoelectronic device, the first and second absolute times T1 and T2 for energy measurement are collected and transferred to the upper configuration (S512).

Of course, at this time, the validity determination unit 600 uses the information of each absolute time corresponding to the gamma ray pair to determine the validity of the corresponding data, and invalidates it if it is determined to be invalid.

Hereinafter, a positron emission tomography apparatus using a multichannel optoelectronic device according to a second exemplary embodiment of the present invention will be described with reference to FIG. 6. 6 is a block diagram of a positron emission tomography apparatus using a multi-channel optoelectronic device according to a second embodiment of the present invention.

As shown in FIG. 6, the positron emission tomography apparatus using the multichannel optoelectronic device according to the second embodiment of the present invention generally includes the positron emission tomography apparatus using the multichannel optoelectronic device according to the first embodiment of the present invention. same.

However, in the second embodiment of the present invention, the first and second measurement units 410 and 420, the first and second information processing units 510 and 520 and the validity judgment that process the output of the photoelectric device digitized by the comparator are used. It is different from the first embodiment of the present invention that the unit 600 includes its function in one configuration (eg, FPGA, Field Programmable Gate Array).

According to the second embodiment of the present invention, the FPGA may configure the number of measuring devices to be larger than the sum of the number m of row signal lines and the number n of column signal lines.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

100: multi-channel photoelectric device unit 110: photoelectric device
210 and 220: first and second amplifiers 211 and 221: amplifiers
310 and 320: first and second comparators 311 and 321: comparators
410, 420: first and second measuring unit 411, 421: measuring unit
510, 520: first and second information processing unit 600: validity determination unit
500: Information Management Department

Claims (7)

A plurality of optoelectronic devices converting an optical signal corresponding to the incident first gamma ray into an electrical signal and configured in a matrix form of rows x columns of (mxn), wherein the plurality of optoelectronic devices are connected to each other in the same row Multi-channel optoelectronic device portion of the first radiation detector is connected to each row signal line and the photoelectric elements of the same column are connected to each other and connected to each column signal line,
Connected to each of m row signal lines connected to an output terminal of the multi-channel optoelectronic device, and receiving the output of the optoelectronic device, and comparing the output of the received optoelectronic device with a first set voltage to produce a first digital signal. A first comparator comprising at least m comparators,
One each connected to n column signal lines connected to an output terminal of the multi-channel optoelectronic device unit to receive the output of the optoelectronic device, and output the output of the optoelectronic device as a second digital signal by comparing with the second set voltage. A second comparator including at least n comparators,
A first measuring unit connected to each comparator of the first comparator, the first measuring unit including at least m measuring devices measuring a first absolute time of a rising edge time point and a second absolute time of a falling edge time point of the first digital signal;
A second measuring unit connected to each comparator of the second comparator, the second measuring unit including at least n measuring devices measuring a third absolute time of the rising edge time point and a fourth absolute time of the falling edge time point of the second digital signal, and
Transmitting the first and second absolute times received from the measuring unit of the first measuring unit as information for measuring energy, and transmitting the third absolute times received from the measuring unit of the second measuring unit as information for measuring precision time difference. Positron emission tomography apparatus using a multi-channel photoelectric device including an information management unit. The method of claim 1,
The photoelectric device is a semiconductor-based photoelectric device or a positron emission tomography apparatus using a multi-channel photoelectric device, characterized in that the photomultiplier tube (PMT, Photomultiplier tube). 3. The method of claim 2,
The semiconductor-based optoelectronic device is a positron emission tomography apparatus using a multi-channel optoelectronic device, characterized in that one of the silicon photomultiplier (SiPM, Silicon Photomultiplier) or Avalanche photo diode (APD). The method of claim 1,
And each of the plurality of optoelectronic devices outputs the electrical signal to each of the row signal line and the column signal line in response to an incident optical signal. The method of claim 1,
And the first set voltages of the m comparators are voltages for determining a width of a signal proportional to the energy of the received signals. The method of claim 5,
And the second set voltages of the n comparators are set differently from the first set voltages. 5. The method of claim 4,
Each measuring unit of the first measuring unit compares the length of a time indicating a value of 1 from the first digital signal with a set time and invalidates the received first digital signal if it is less than a set time. Tomography device.

Images