Hybrid output detector and detection system

Abstract

The present invention discloses a hybrid output detector and a detection system, comprising a semiconductor material, a charge-sensitive preamplifier circuit, a rapid shaping circuit, a photon counting circuit, an energy integration circuit, and a signal output unit; the semiconductor material receives X-rays and converts them into a rapid pulse current signal for output; the output end of the semiconductor material is sequentially connected to the charge-sensitive preamplifier circuit and the rapid shaping circuit, for converting the rapid pulse current signal into a voltage pulse signal for output; the output end of the rapid shaping circuit is respectively connected to the photon counting circuit and the energy integration circuit, for converting the voltage pulse signal into a photon counting signal and an energy integration signal, respectively; the input end of the signal output unit is respectively connected to the photon counting circuit and the energy integration circuit, and outputs a signal according to demand; the output signal is a photon counting signal and / or an energy integration signal, thereby improving the working efficiency of the hybrid output detector and the accuracy of the output signal.

Description

Technical Field

[0001] The present invention relates to the field of medical imaging technology, and in particular to a hybrid output detector and a detection system. Background Art

[0002] Since its invention, CT has been widely used in medical applications. Over the past few decades, CT system image quality has significantly improved, driven by technological breakthroughs in both hardware and software. For example, CT system detectors have evolved from single- and dual-row detectors to systems with 256 rows, exponentially increasing system complexity. As a crucial component in CT systems, detectors have a crucial impact on system performance and image quality. Currently, all medical CT systems utilize detectors based on a third-generation helical scanning structure. These detectors utilize a rare-earth ceramic scintillator to convert incident X-ray photons into visible light, which is then read out by a subsequent photodiode. In recent years, spectral scanning and spectral imaging have been introduced into CT systems, and manufacturers have launched CT systems based on spectral scanning. To achieve spectral imaging, signals from different energy ranges must be acquired and decomposed. Most current spectral CT systems are based on existing CT hardware, with minor improvements. For example, some manufacturers use voltage switching to implement spectral scanning on existing systems. Others add a set of tubes and detectors, each using different voltages, to also achieve spectral scanning. Furthermore, some manufacturers use a dual-layer detector solution, exploiting the differential attenuation of X-rays of different energies in the detector to read out limited spectral information.

[0003] In recent years, photon-counting energy spectrum detectors have been gradually introduced into medical CT products. This is because these detectors are naturally capable of counting at different energies, making them ideal for energy spectrum scanning and achieving optimal image quality. Compared to photon-counting detectors, the signal from a traditional CT detector is the integral of all photon energies over a period of time (a scanning angle). Photon-counting detectors, on the other hand, use room-temperature semiconductor materials to directly convert each incident X-ray photon into a rapid pulse of electrical signal. The pulse height is proportional to the energy of the incident X-ray photon. Counting circuits corresponding to multiple energy windows record the number of all pulses (X-ray photons) corresponding to multiple energy windows over a period of time, yielding the final output signal and energy spectrum information.

[0004] Due to limitations in materials and circuit characteristics, existing counting detectors can experience pulse accumulation at high count rates, leading to output deviations and even detector inactivity. To increase the detector's count rate per unit area, existing technologies primarily employ small pixel designs, reducing the signal count rate per pixel. This increases the number of parallel processing readout circuit channels, significantly increasing circuit complexity and cost.

[0005] In actual scanning, the X-ray count rate corresponding to each detector varies greatly, making it difficult for a single-mode detector to meet the final requirements. Traditional integrating detectors perform better for high-dose / high-count-rate signals, but suffer from high signal noise at low doses / low count rates. Photon counting detectors, on the other hand, perform better for low-dose / low-count-rate signals, but are prone to readout count rate saturation and energy spectrum distortion due to pulse pile-up for high-dose / high-count-rate signals. Summary of the Invention

[0006] Technical purpose: In response to the defects in the existing technology, the present invention discloses a hybrid output detector and a detection system. The output signal in each hybrid output detector can simultaneously include a photon counting signal and an energy integration signal, and output a photon counting signal or an energy integration signal for different counting rates, thereby improving the working efficiency of the hybrid output detector and the accuracy of the output signal.

[0007] Technical solution: In order to achieve the above technical objectives, the present invention adopts the following technical solution.

[0008] A hybrid output detector comprises a semiconductor material, a charge-sensitive preamplifier circuit, a rapid shaping circuit, a photon counting circuit, an energy integration circuit and a signal output unit; the semiconductor material is used to receive X-rays, convert each incident X-ray photon into a rapid pulse current signal and then output it; the output end of the semiconductor material is sequentially connected to the charge-sensitive preamplifier circuit and the rapid shaping circuit, and is used to convert the rapid pulse current signal into a voltage pulse signal and then output it; the output end of the rapid shaping circuit is respectively connected to the photon counting circuit and the energy integration circuit; the photon counting circuit is used to convert the voltage pulse signal into a photon counting signal; the energy integration circuit is used to convert the voltage pulse signal into an energy integration signal; the input end of the signal output unit is respectively connected to the photon counting circuit and the energy integration circuit, and outputs a signal according to demand; the output signal is a photon counting signal and / or an energy integration signal.

[0009] Preferably, the signal output unit is further provided with a signal selector for outputting a signal according to demand, and the signal output formula is:

[0010]

[0011] Among them, Iout is the output signal, I pc is the photon counting signal, I ei is the energy integration signal, and I3 is the third counting rate.

[0012] Preferably, the output signal is a photon counting signal, and before outputting the photon counting signal, the method further includes correcting the photon counting signal using the energy integration signal and outputting the corrected photon counting signal, wherein the correction formula is:

[0013]

[0014] Among them, I′ pc is the corrected photon counting signal, I pc is the photon counting signal, I ei is the energy integration signal, k is the characteristic parameter of the hybrid output detector, and I0 is the first counting rate.

[0015] Preferably, the output signal is an energy integration signal, and before outputting the energy integration signal, the energy integration signal is corrected using a photon counting signal, and the corrected energy integration signal is output, and the correction formula is:

[0016]

[0017] Among them, I′ ei is the corrected energy integral signal, I pc is the photon counting signal, I ei is the energy integration signal, c is the characteristic parameter of the hybrid output detector, and I1 is the second counting rate.

[0018] Preferably, the semiconductor material is CdTe, the photon counting circuit includes a threshold discrimination circuit and a counting circuit, which are used to obtain photon counting signals corresponding to multiple energy windows; the energy integration circuit includes a low-pass filter, a signal integration circuit and a sampling circuit, which obtains the energy integration signal of the incident photon.

[0019] A hybrid output detector system comprises several hybrid output detectors as described above, each hybrid detector outputting a signal according to demand, wherein the output signal is a photon counting signal and / or an energy integration signal. The hybrid output detector system outputs several output signals, wherein the several output signals are photon counting signals and / or energy integration signals.

[0020] Beneficial effects:

[0021] 1. The output signal of each hybrid output detector of the present invention can include both a photon counting signal and an energy integration signal. Photon counting signals or energy integration signals are output for different counting rates, thereby improving the working efficiency of the hybrid output detector and the accuracy of the output signal.

[0022] 2. The present invention uses the energy integration signal to correct the photon counting signal, thereby improving the accuracy of the photon counting signal at high counting rates;

[0023] 3. The present invention uses a photon counting signal to correct the energy integration signal, so that the energy integration signal contains energy spectrum information, thereby improving the accuracy of the energy integration signal at low counting rates. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the overall structure of the hybrid output detector of the present invention;

[0025] Figure 2 A schematic diagram of an output signal of a hybrid output detector of the present invention;

[0026] Figure 3 A schematic diagram of a hybrid output detector of the present invention outputting two signals;

[0027] Figure 4 Schematic diagram of the hybrid output detector of the present invention outputting a corrected photon counting signal;

[0028] Figure 5 This is a schematic diagram of the energy integration signal after the hybrid output detector of the present invention outputs a correction;

[0029] Figure 6 Schematic diagram of output signals of the hybrid output detector system of the present invention. DETAILED DESCRIPTION

[0030] The following further describes and explains a hybrid output detector and a detection system of the present invention in conjunction with the accompanying drawings.

[0031] As attached Figure 1 and attached Figure 2As shown, a hybrid output detector includes a semiconductor material, a charge-sensitive preamplifier circuit, a rapid shaping circuit, a photon counting circuit, an energy integration circuit, and a signal output unit. The principles of each circuit unit are referenced in the existing public document "Nuclear Electronics," by Wang Jingjin, Fan Tianmin, Qian Yonggeng, et al., with the unified book number 15175-484, published in 1983. The semiconductor material is used to receive X-rays and convert each incident X-ray photon into a rapid pulse current signal for output. The output end of the semiconductor material is sequentially connected to the charge-sensitive preamplifier circuit and the rapid shaping circuit, for converting the rapid pulse current signal into a voltage pulse signal for output. The output end of the rapid shaping circuit is respectively connected to the photon counting circuit and the energy integration circuit, for converting the voltage pulse signal into a photon counting signal, and the energy integration circuit is respectively connected to the voltage integration circuit. The input end of the signal output unit is respectively connected to the photon counting circuit and the energy integration circuit, and outputs a signal as required, the output signal being a photon counting signal and / or an energy integration signal.

[0032] The semiconductor material is CdTe, and the photon counting circuit includes a threshold discrimination circuit and a counting circuit to obtain photon counting signals corresponding to multiple energy windows. The energy integration circuit includes a low-pass filter, a signal integration circuit, and a sampling circuit to obtain an energy integration signal of the incident photons. The principles of each circuit unit are referenced from the existing public document "Nuclear Electronics," by Wang Jingjin, Fan Tianmin, Qian Yonggeng, et al., with the unified book number: 15175-484, published in 1983.

[0033] As attached Figure 3 As shown, the signal output unit is further provided with a signal selector for outputting a signal according to demand. The output signal is a photon counting signal and / or an energy integration signal, and the signal output formula is:

[0034]

[0035] Among them, I out is the output signal, I pc is the photon counting signal, I ei is the energy integration signal, I3 is the third counting rate, which is related to the mixed output detector and is determined by experiments. In some embodiments of the present invention, the value is generally 10 7 / sec / mm 2 , that is 10,000,000 / second / square mm;

[0036] The output signal of each hybrid output detector of the present invention can include a photon counting signal and an energy integration signal at the same time, and output a photon counting signal or an energy integration signal for different counting rates, thereby improving the working efficiency of the hybrid output detector and the accuracy of the output signal. For example, when the X-ray counting rate is low, it switches to a photon counting signal, and when the X-ray counting rate is high, it switches to an energy integration signal. In this way, on the one hand, only one output signal needs to be processed at all times, which simplifies the readout of the detector. On the other hand, it can ensure that the detector has an effective output signal in the entire X-ray counting rate range from low to high.

[0037] As attached Figure 4 As shown, in step S3, the output signal is a photon counting signal. Before outputting the photon counting signal, the photon counting signal is corrected using the energy integration signal, and the corrected photon counting signal is output. The correction formula is:

[0038]

[0039] Among them, I′ pc is the corrected photon counting signal, I pc is the photon counting signal, I ei is the energy integration signal, k is the characteristic parameter of the hybrid output detector, which mainly depends on the relationship between charge and current conversion in the circuit. The specific value should be determined through experiments. In some embodiments of the present invention, the value is 1000; I0 is the first counting rate, which is related to the hybrid output detector and is determined through experiments. In some embodiments of the present invention, the value is generally 10 6 / sec / mm 2 , that is, 1,000,000 / second / square mm;

[0040] In the present invention, the energy integration signal is used to correct the photon counting signal, thereby improving the accuracy of the photon counting signal at a high counting rate.

[0041] As attached Figure 5 As shown, in step S3, the output signal is an energy integration signal. Before outputting the energy integration signal, the energy integration signal is corrected using the photon counting signal, and the corrected energy integration signal is output. The correction formula is:

[0042]

[0043] Among them, I′ ei is the corrected energy integral signal, I pc is the photon counting signal, I eiis the energy integration signal, c is the characteristic parameter of the hybrid output detector, which mainly depends on the relationship between charge and current conversion in the circuit. The specific value should be determined through experiments. In some embodiments of the present invention, the value is 1000; I1 is the second counting rate, which is related to the hybrid output detector and is determined through experiments. In some embodiments of the present invention, the value is generally 10 5 / sec / mm 2 , that is, 100,000 / second / square mm;

[0044] The present invention uses a photon counting signal to correct an energy integration signal, so that the energy integration signal includes energy spectrum information, thereby improving the accuracy of the energy integration signal at a low counting rate.

[0045] In response to the inherent shortcomings of traditional detectors in different modes, the present invention discloses a hybrid output detector that can simultaneously output photon counting signals and (or) energy integration signals, and can seamlessly switch between the two modes, integrating the advantages of photon counting and traditional energy integration detectors. For example, in high-dose mode, the accumulation of photon counting signals is serious and the counting signal error is large. At this time, the main output mode of the detector is based on the energy integration signal. Under normal doses, both photon counting signals and energy integration signals can be used, and combining them can also obtain more information and higher accuracy. Under low doses, the energy integration signal is affected by electronic noise and the like, and the error is large. Therefore, in this case, the output of the detector is mainly based on the photon counting signal.

[0046] As attached Figure 6 As shown, a hybrid output detector system includes several hybrid output detectors as described above, each hybrid detector outputs a signal according to demand, the output signal is a photon counting signal and / or an energy integration signal, and the hybrid output detector system outputs several output signals, several of which are photon counting signals and / or energy integration signals.

[0047] The present invention expands the operating range of the hybrid output detector, can provide effective and accurate sampling data under a wide range of X-ray photon counting rates, can operate in multiple working modes, and can seamlessly switch between energy integration and photon counting modes.

[0048] Example:

[0049] In this embodiment, the output of a hybrid output detector is determined according to the following formula:

[0050]

[0051] Among them, I out is the output signal, I pc is the photon counting signal, I eiThe coefficients k1 and k2 are related to the calibration and correction between the photon counting signal and the energy integration signal, and are usually determined by experiments. In this embodiment, at a high counting rate, that is, when the photon counting signal exceeds 10 7 / sec / mm 2 When the output signal is the energy integral signal corrected by the coefficient k2, the photon counting signal is 10 6 / sec / mm 2 to 10 7 / sec / mm 2 When the output signal is between 10 and 10, the output signal is the energy integral signal corrected by the coefficient k1, and the photon counting signal does not exceed 10 6 / sec / mm 2 When , the output signal is directly a photon counting signal.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hybrid output detector, characterized in that: The device comprises a semiconductor material, a charge-sensitive preamplifier circuit, a rapid shaping circuit, a photon counting circuit, an energy integration circuit, and a signal output unit; the semiconductor material is used to receive X-rays, convert each incident X-ray photon into a rapid pulse current signal, and then output the signal; the output end of the semiconductor material is sequentially connected to the charge-sensitive preamplifier circuit and the rapid shaping circuit, and is used to convert the rapid pulse current signal into a voltage pulse signal and then output the signal; the output end of the rapid shaping circuit is respectively connected to the photon counting circuit and the energy integration circuit; the photon counting circuit is used to convert the voltage pulse signal into a photon counting signal; the energy integration circuit is used to convert the voltage pulse signal into an energy integration signal; the input end of the signal output unit is respectively connected to the photon counting circuit and the energy integration circuit, and outputs a signal according to demand; the output signal is a photon counting signal and / or an energy integration signal; The output signal is a photon counting signal. Before outputting the photon counting signal, the photon counting signal is corrected using the energy integration signal, and the corrected photon counting signal is output. The correction formula is: Among them, I' pc is the corrected photon counting signal, I pc is the photon counting signal, I ei is the energy integration signal, k is the characteristic parameter of the hybrid output detector, and I0 is the first counting rate.

2. A hybrid output detector according to claim 1, characterized in that: The signal output unit is further provided with a signal selector for outputting signals according to requirements, and the signal output formula is: Among them, I out is the output signal, I pc is the photon counting signal, I ei is the energy integration signal, and I3 is the third counting rate.

3. The hybrid output detector according to claim 1, wherein: The output signal is an energy integration signal. Before outputting the energy integration signal, the energy integration signal is corrected using a photon counting signal, and the corrected energy integration signal is output. The correction formula is: Among them, I' ei is the corrected energy integral signal, I pc is the photon counting signal, I ei is the energy integration signal, c is the characteristic parameter of the hybrid output detector, and I1 is the second counting rate.

4. The hybrid output detector according to claim 1, wherein: The semiconductor material is CdTe, the photon counting circuit includes a threshold discrimination circuit and a counting circuit, which are used to obtain photon counting signals corresponding to multiple energy windows; the energy integration circuit includes a low-pass filter, a signal integration circuit and a sampling circuit, which obtains the energy integration signal of the incident photon.

5. A hybrid output detector system, characterized in that: It comprises several hybrid output detectors as described in any one of claims 1-4, each hybrid detector outputs a signal according to demand, the output signal is a photon counting signal and / or an energy integration signal, and the hybrid output detector system outputs several output signals, and the several output signals are photon counting signals and / or energy integration signals.

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