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JP-2026076135-A - Positron emission tomography system, positron emission tomography method, and gamma-ray detector

JP2026076135AJP 2026076135 AJP2026076135 AJP 2026076135AJP-2026076135-A

Abstract

[Problem] To provide both good time-of-flight resolution and interaction depth information. [Solution] The positron emission tomography apparatus according to this embodiment comprises a scintillation array and a photosensor array. The scintillation array includes a plurality of scintillator crystal units individually separated by a reflective material, and each scintillator crystal unit is configured to generate scintillation light in response to gamma-ray interactions within the scintillator crystal unit caused by gamma-ray irradiation from a subject, and has a substructure for decoding two or more depths within the scintillator crystal unit such that gamma-ray interactions at different depths cause scintillation light to escape from the photo-escape plane of the scintillator crystal unit in different patterns. The photosensor array converts the scintillation light received from the scintillation array into an electrical signal. [Selection Diagram] Figure 11B

Inventors

  • ペン ペン
  • シャオリ リ
  • イ チャン

Assignees

  • キヤノンメディカルシステムズ株式会社

Dates

Publication Date
20260511
Application Date
20251022
Priority Date
20241023

Claims (12)

  1. A scintillation array comprising a plurality of scintillator crystal units individually separated by a reflective material, wherein each scintillator crystal unit is configured to generate scintillation light in response to gamma-ray interactions within the scintillator crystal unit caused by gamma-ray irradiation from a subject, and the scintillation array having a substructure for decoding two or more depths within the scintillator crystal unit such that gamma-ray interactions at different depths cause scintillation light to escape from the photo-escape surface of the scintillator crystal unit in different patterns, A photosensor array coupled to the scintillation array converts scintillation light received from the scintillation array into an electrical signal, A positron emission tomography apparatus comprising: a processing circuit that extracts information representing the interaction depth of the gamma-ray interaction in the scintillation array from the electrical signal, and reconstructs an image of the subject based on the extracted information.
  2. Each of the scintillator crystal units comprises a substructure containing a crystalline bulk body having an optical barrier disposed within the substructure, wherein the optical barrier is a microcrack formed inside the crystalline bulk body through a laser engraving process. The positron emission tomography apparatus according to claim 1.
  3. The substructure of each scintillator crystal unit is configured such that the optical barrier separates the crystalline bulk into four parts, and the gamma-ray interaction in the four parts generates scintillation light escaping from the optical escape plane of the scintillator crystal unit in four different patterns. The positron emission tomography apparatus according to claim 2.
  4. The substructure of each scintillator crystal unit is configured such that the optical barrier separates the crystal bulk into eight parts, and the gamma-ray interactions in the eight parts cause scintillation light to escape from the photo-escape plane of the scintillator crystal unit in eight different patterns. The positron emission tomography apparatus according to claim 2.
  5. The substructure of each scintillator crystal unit comprises a plurality of subcrystals, and the plurality of subcrystals have a reflective material and an optical adhesive applied to different contact interfaces between the plurality of subcrystals. A positron emission tomography apparatus according to any one of claims 1 to 4.
  6. The substructure of each scintillator crystal unit includes four subcrystals, and the gamma-ray interactions in the four subcrystals are configured to produce scintillation light escaping from the photo-escape plane of the scintillator crystal unit in four different patterns. The positron emission tomography apparatus according to claim 5.
  7. The substructure of each scintillator crystal unit comprises eight subcrystals, and the gamma-ray interactions in the eight subcrystals are configured to produce scintillation light escaping from the photo-escape plane of the scintillator crystal unit in eight different patterns. The positron emission tomography apparatus according to claim 5.
  8. The aforementioned processing circuit is Based on the aforementioned electrical signals, information (t, x, y, e) regarding the timing, position, and energy of the gamma-ray interaction within the scintillation array is derived. Based on the derived information (t, x, y, e), information representing the interaction depth of the gamma-ray interaction within the scintillation array is determined. A positron emission tomography apparatus according to any one of claims 1 to 4.
  9. The processing circuit determines information representing the interaction crystal, interaction energy, and interaction time related to the gamma-ray interaction within the scintillation array based on the derived information (t, x, y, e). The positron emission tomography apparatus according to claim 8.
  10. The aforementioned optical sensor array is composed of finer particles compared to the scintillation array. A positron emission tomography apparatus according to any one of claims 1 to 4.
  11. A positron emission tomography (PT) method applied to a positron emission tomography apparatus comprising: a scintillation array including a plurality of scintillator crystal units individually separated by a reflective material, wherein each scintillator crystal unit is configured to generate scintillation light in response to gamma-ray interactions within the scintillator crystal unit caused by gamma-ray irradiation from a subject, and the scintillation array having a substructure for decoding two or more depths within the scintillator crystal unit such that gamma-ray interactions at different depths cause scintillation light to escape from the photo-escape plane of the scintillator crystal unit in different patterns; a photosensor array coupled to the scintillation array; and a processing circuit. The scintillator crystal unit included in the scintillation array generates scintillation light in response to gamma-ray interactions within the scintillator crystal unit, The optical sensor array performs the step of converting scintillation light received from the scintillation array into an electrical signal, A positron emission tomography (PT) method comprising the steps of: the processing circuit extracting information representing the interaction depth of the gamma-ray interaction in the scintillation array from the electrical signal; and reconstructing an image of the subject based on the extracted information.
  12. A gamma-ray detector used in a positron emission tomography (PTMO) scanner, A gamma-ray detector comprising a scintillation array including a plurality of scintillator crystal units individually separated by a reflective material, wherein each scintillator crystal unit is configured to generate scintillation light in response to gamma-ray interactions within the scintillator crystal unit caused by gamma-ray irradiation from a subject, and the scintillation array having substructures for decoding two or more depths within the scintillator crystal unit such that gamma-ray interactions at different depths cause scintillation light to escape from the photo-escape plane of the scintillator crystal unit in different patterns.

Description

The embodiments disclosed herein and in the drawings relate to a positron emission tomography (PTMO) system, a positron emission tomography (PTMO) method, and a gamma-ray detector. Positron emission tomography (PET) is a functional imaging modality that uses radioactive tracers to image biochemical processes in humans or animals. In PET imaging, the tracer agent is administered to the patient by injection, inhalation, or ingestion. After administration, the drug concentrates in specific locations within the patient's body due to its physical and biomolecular properties. The actual spatial distribution of the drug, the intensity of drug accumulation areas, and the dynamics of the process from administration to final excretion are all factors that can have clinical significance. During this process, the tracer attached to the drug emits positrons. When these emitted positrons collide with electrons, an annihilation event occurs, in which the positron and electron combine. This annihilation event generates two gamma-ray photons that travel approximately 180 degrees apart (at 511 keV). Time-of-flight (TOF) and depth-of-interaction (DOI) are two important metrics for evaluating the performance of a PET scanner. In different applications, it may be preferable to prioritize one over the other. In clinical PET scanners, Time-of-Flight (TOF) is considered more important than Dosimeter (DOI). TOF functionality improves the system's effective sensitivity and is essential for clinical applications. This improvement leads to better image quality and a reduction in the radiation dose administered to the patient. In clinical PET scanners, the bore diameter is relatively large, so DOI does not play a particularly important role. Conversely, in preclinical PET scanners characterized by small bore diameters, the importance of DOI information increases. The DOI function plays a crucial role in improving spatial resolution by correcting parallax errors, which are a particular concern in preclinical applications. Furthermore, DOI information has been confirmed to contribute to improving TOF resolution. Moreover, DOI becomes even more important in correcting errors caused by the significant tilt of the response line along the axial direction when the axial length of clinical PET scanners is long, such as whole-body scanners. To improve the overall performance of clinical PET scanners, there is a need for scanners that possess both good TOF resolution and DOI (Dynamic Occlusion) capabilities. U.S. Patent Application Publication No. 2012/0235047U.S. Patent Application Publication No. 2016/0170040U.S. Patent Application Publication No. 2022/0214464European Patent Application Publication No. 4163678 With reference to the following figures, various embodiments of this disclosure proposed as examples will be described in detail. Here, similar reference numerals indicate similar elements. Figure 1 shows the parallax error caused by oblique line-of-response (LOR) in a pair of pixels of a positron emission tomography (PET) detector that does not have interaction depth (DOI) functionality.Figure 2 shows a typical single-ended readout configuration in which the pixel array of the scintillator crystal unit is coupled to the top of the pixel array of the photosensor.Figure 3 shows a modified single-ended readout configuration according to the present disclosure, in which each scintillator crystal unit of the pixelation array has a substructure for decoding DOI information.Figure 4 shows an exemplary substructure design inside a scintillator crystal unit according to an embodiment of the present disclosure.Figure 5A shows an exemplary substructure design inside a scintillator crystal unit according to an embodiment of the present disclosure.Figure 5B shows an exemplary substructure design inside a scintillator crystal unit according to an embodiment of the present disclosure.Figure 6A shows an exemplary scintillator crystal unit including four segments according to an embodiment of the present disclosure.Figure 6B shows a flood histogram formed when gamma rays are irradiated onto the four segments shown in Figure 6A.Figure 7A shows an exemplary scintillator crystal unit including eight segments according to an embodiment of the present disclosure.Figure 7B shows a flood histogram formed when gamma rays are irradiated onto the eight segments shown in Figure 7A.Figure 8 shows an exemplary scenario in which a pixelated photosensor array is directly coupled to a pixelated array of a scintillator crystal unit according to an embodiment of the present disclosure.Figure 9 shows an exemplary electronic device design for acquiring timing, position, and energy information (t, x, y, e) from a pixelated optical sensor array, according to an embodiment of the present disclosure.Figure 10 is a flowchart showing an exemplary procedure 1000 for extracting DOI information according to an embodiment of this disclosure.Figure 11A is a perspective view of a PET