c. The emission positron from radio-isotope can shift 1 mm in human body, and then combined with an electron in tissues and annihilate to produce two equal energy (511 Kev and opposite y photons It was recognized that detection of these photons, using the property that they are emitted simultaneously in opposite directions, would permit description, in three dimensions, of the distribution of the radionuclides in the body
c. The emission positron from radio-isotope can shift 1 mm in human body, and then combined with an electron in tissues and annihilate to produce two equal energy (511 KeV) and opposite γ photons. It was recognized that detection of these photons, using the property that they are emitted simultaneously in opposite directions, would permit description, in three dimensions, of the distribution of the radionuclides in the body
Sketch map of pet PET imaging of an object surrounded by a ring of detectors. Annihilation photons pa are recorded by detectors on opposite sides of the ring the relative intensities allow determination of the mass thickness of the distances ll and L2 in the patient through which these photons travel
Sketch map of PET PET imaging of an object surrounded by a ring of detectors. Annihilation photons γa are recorded by detectors on opposite sides of the ring, the relative intensities allow determination of the mass thickness of the distances L1 and L2 in the patient through which these photons travel
d. Annihilation photons leaving the body are detected by an array of detectors that surround the patient. Events are recorded only when two detectors each detect an annihilation photon simultaneously, i.e., within 10 to 25 ns of each other. Events separated further in time are not recorded
d. Annihilation photons leaving the body are detected by an array of detectors that surround the patient. Events are recorded only when two detectors each detect an annihilation photon simultaneously, i.e., within 10 to 25 ns of each other. Events separated further in time are not recorded
The line joining the two recording detectors is a line of response (Lor) along which the annihilation photons have traveled and on which the positron decay occurred. This coincident detection technique allows a determination of the direction of the annihilation photons without the physical collimation needed in SPect. For this reason coincident detection is often called electronic collimation
The line joining the two recording detectors is a line of response (LOR) along which the annihilation photons have traveled and on which the positron decay occurred. This coincident detection technique allows a determination of the direction of the annihilation photons without the physical collimation needed in SPECT. For this reason coincident detection is often called electronic collimation
Two dual PMTs 6x6 BGO crystals Light sealing Plastic Protective sheet Figure 14.12. Ring structure for the GE Ad. Figure 14.13. Detector block structure for the vance PEr scanner showing the 336 detector GE Advance PETscanner. Each block contains block 36 BGO detector cystals. PMT:光电倍增管( Photo Multiplier Tube) BG0:锗酸铋( Bi smut German ium0xide)
BGO： 锗酸铋(Bismuth Germanium Oxide） PMT：光电倍增管(Photo Multiplier Tube)