Detection systems are a key component of any imaging system, and an understanding of their properties is important for establishing appropriate operating criteria or designing schemes for obtaining quantitative information. In this section scintillation detection systems, which are used in the majority of PET tomographs, are discussed. The scintil
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lation process involves the conversion of high-energy photons into visible light via interaction with a scintillating material, and consists of the following steps: In a scintillation detector, the scintillator is optically coupled to a photomultiplier tube (PMT) which then generates an electrical signal in response to light incident upon its face. There are several variations on this theme which are used in PET - for example, a 2D array of crystals may be coupled to 4 PMTs (the block-detector, Casey and Nutt, 1986 ), an array of PMTs may be coupled to a single planar crystal (the Anger camera, Anger, 1958 ), or an array of crystals may be coupled to a multi-channel PMT ( Cherry et al 1997 ). Compton scatter and photo-electric absorption generate electrons of differing energy distributions. In photo-electric absorption, all the photon energy is transferred to the electron, and the energy distribution of the photo-electrons is sharply peaked close to the energy of the incident photon. In Compton scatter, the recoil electrons have a range of energies, depending on the scattering angle. From equation 1 we can say that the energy of the recoil electron will be where q is the photon scattering angle, Ebis the energy of the electron, E is the energy of the incident photon and EG is the energy of the scattered photon. Ebreaches a maximum when q = p. For 511 keV photons, this value is 340. 7 keV. A typical energy distribution for...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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