Image acquisition device and image acquisition method

An image acquisition apparatus comprising:

• a measurement unit including a first detector and a second detector each configured to detect a gamma-ray photon, and configured to output a signal indicating a detection position and a detection time when each of the first detector and the second detector detects the gamma-ray photon;
• and
• a processing unit configured to process the signal output from each of the first detector and the second detector, wherein
• the measurement unit, in a state in which a subject into which a drug labeled with a positron emitting radionuclide is injected is placed between the first detector and the second detector, and a positron emitting radionuclide is placed between the first detector or the second detector and the subject, outputs the signal indicating the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector, and
• the processing unit,
• for each coincidence event in which the first detector and the second detector perform coincidence detection of a pair of gamma-ray photons generated by an electron positron annihilation event in the positron emitting radionuclide,
• in a case in which the gamma-ray photon arriving at one detector out of the first detector and the second detector is a gamma-ray photon arriving without being Compton scattered in the subject, and the gamma-ray photon arriving at another detector is a gamma-ray photon arriving after being Compton scattered in the subject, determines a position at which the gamma-ray photon is Compton scattered in the subject based on the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector and a position of the positron emitting radionuclide placed between the first detector or the second detector and the subject,
• in a case in which the gamma-ray photons arriving at both the first detector and the second detector are gamma-ray photons arriving without being Compton scattered in the subject, determines a position at which the annihilation event occurs based on the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector,
• creates a first tomographic image representing a distribution of Compton scattering positions in the subject respectively determined for a plurality of coincidence events, creates a second tomographic image representing a distribution of annihilation event occurrence positions in the subject respectively determined for a plurality of coincidence events, and corrects the second tomographic image based on the first tomographic image.

An image acquisition method comprising:

• a measurement step of using a first detector and a second detector each configured to detect a gamma-ray photon, and outputting a signal indicating a detection position and a detection time when each of the first detector and the second detector detects the gamma-ray photon;
• and
• a processing step of processing the signal output from each of the first detector and the second detector, wherein
• the measurement step, in a first measurement mode, in a state in which a subject is placed between the first detector and the second detector, and a positron emitting radionuclide is placed between the first detector or the second detector and the subject, outputs the signal indicating the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector, and
• the processing step, in the first measurement mode,
• for each coincidence event in which the first detector and the second detector perform coincidence detection of a pair of gamma-ray photons generated by an electron positron annihilation event in the positron emitting radionuclide,
• assuming that the gamma-ray photon arriving at one detector out of the first detector and the second detector is a gamma-ray photon arriving without being Compton scattered in the subject, and the gamma-ray photon arriving at another detector is a gamma-ray photon arriving after being Compton scattered in the subject, determines a position at which the gamma-ray photon is Compton scattered in the subject based on the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector and a position of the positron emitting radionuclide, and creates a first tomographic image representing a distribution of Compton scattering positions in the subject respectively determined for a plurality of coincidence events.

An image acquisition method comprising:

• a measurement step of using a first detector and a second detector each configured to detect a gamma-ray photon, and outputting a signal indicating a detection position and a detection time when each of the first detector and the second detector detects the gamma-ray photon;
• and
• a processing step of processing the signal output from each of the first detector and the second detector, wherein
• the measurement step, in a state in which a subject into which a drug labeled with a positron emitting radionuclide is injected is placed between the first detector and the second detector, and a positron emitting radionuclide is placed between the first detector or the second detector and the subject, outputs the signal indicating the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector, and
• the processing step,
• for each coincidence event in which the first detector and the second detector perform coincidence detection of a pair of gamma-ray photons generated by an electron positron annihilation event in the positron emitting radionuclide,
• in a case in which the gamma-ray photon arriving at one detector out of the first detector and the second detector is a gamma-ray photon arriving without being Compton scattered in the subject, and the gamma-ray photon arriving at another detector is a gamma-ray photon arriving after being Compton scattered in the subject, determines a position at which the gamma-ray photon is Compton scattered in the subject based on the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector and a position of the positron emitting radionuclide placed between the first detector or the second detector and the subject,
• in a case in which the gamma-ray photons arriving at both the first detector and the second detector are gamma-ray photons arriving without being Compton scattered in the subject, determines a position at which the annihilation event occurs based on the detection position and the detection time of the gamma-ray photon by each of the first detector and the second detector,
• creates a first tomographic image representing a distribution of Compton scattering positions in the subject respectively determined for a plurality of coincidence events, creates a second tomographic image representing a distribution of annihilation event occurrence positions in the subject respectively determined for a plurality of coincidence events, and corrects the second tomographic image based on the first tomographic image.