Pet detector scintillator arrangement with light sharing and depth of interaction estimation

A photon detector, comprising:

• a sensor array of optical sensors disposed in a plane, each optical sensor configured to sense light intensity;
• a scintillator array of four scintillation crystal bars including a first scintillator crystal bar, a second scintillator crystal bar, a third scintillator crystal bar, and a fourth scintillator crystal bar, each of the four scintillation crystal bars being a rectangular prism with four side surfaces and first and second end surfaces, each scintillation crystal bar configured to generate a light scintillation in response to interacting with a received gamma photon, the four scintillator crystal bars being arranged such that:
• the first scintillation crystal bar has a first face facing and adjacent a first face of the second scintillator crystal bar,
• the first scintillation crystal bar has a second face facing and adjacent a first face of the third scintillator crystal bar,
• the second scintillation crystal bar has a second face facing and adjacent a first face of the fourth scintillator crystal bar, and
• the third scintillation crystal bar has a second face facing and adjacent a second face of the fourth scintillator crystal bar;
• a first layer disposed in a first plane between and adjacent the first face of the first scintillation crystal bars and the first face of the second scintillation crystal bar with a first light sharing portion adjacent the first end surface and a first reflective portion adjacent the second end surface;
• a second layer disposed in a second plane orthogonal to the first plane and disposed between and adjacent the second face of the first scintillation crystal bars and the first face of the third scintillation crystal bar with a second light sharing portion adjacent the second end surface and a second reflective portion adjacent the first end surface;
• a third layer that is reflective and disposed adjacent to and covering third and fourth side surfaces of the first, second, third and fourth scintillation crystal bars, such that the scintillator array is optically isolated from adjacent scintillator arrays;
• a signal processor connected to the sensor array configured to estimate a depth of interaction (DOI) of a gamma photon interacting with one of the first, second, third, and fourth scintillation crystal bars of the scintillator array based on a ratio of light sensed from only the first and fourth of the four scintillation crystal bars which are disposed diagonally to each other and/or a ratio of light sensed from only the second and third scintillation crystal bars which are disposed diagonally to each other.