CH5 scintillation detectors and CH6 imaging instrumentation

Connect the following events with the corresponding components of a scintillation detector

1. photomultiplier tube

the multiplying action of successive steps yields a very large number of electrons in response to each photoelectron

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

1. photopeak

energy of photon source

true or false: a detector that can distinguish separate photopeak’s at 200 and 205keV has a better energy resolution than a detector that can only distinguish photopeak’s as close as 200 and 250keV

true

match each of the listed terms below to one of the following definitions

1. Z-pulse

electrical output from the preamplifier and amplifier connected to a photomultiplier tube in response to a photon interaction in the crystal

match each of the listed terms below to one of the following definitions

pulse height analyzer

used to select Z-pulses within the upper and lower limits of the energy window

match each of the listed terms below to one of the following definitions

energy window

range of acceptable photon energies

a single 15% energy window is set symmetrically on the 159keV photopeak for an iodine-123 imaging study in a gamma camera the lower the upper energy windows are

147 and 171keV

scintillation detectors convert

gamma ray energy into visible light

photomultiplier tubes

convert visible light into electrons that are then accelerated to provide amplification

True or False: a parallel-hole collimator providing both high sensitivity and high resolution is difficult to design principally because the requirements for sensitivity conflict with those for resolution

true

starting with a standard low-energy all-purpose collimator with will happen to the images if you alter the collimator deign by

1. lengthening the bores

higher resolution lower sensitivity

starting with a standard low-energy all-purpose collimator what will happen to the images if you alter the collimator deign by

1. thickening the septa

less septal penetration with higher energy phonons

starting with a standard low-energy all-purpose collimator what will happen to the images if you alter the collimator deign by

increasing the number of holes while decreasing the size of each hole

higher resolution lower sensitivity

true or false: in a converging-hole collimator the holes angle inward toward the organ to be imaged in consequence the organ appears larger at the face of the crystal

ture

how many pixels of data can be stored in 64X64 image matrix

4096

the usual gamma camera head contains all of the following elements except

1. crystal

2. photomultiplier tubes

3. collimator

4. positioning circuit

5. pulse-heigh analyzer

6. focusing assembly

focusing assembly

match the part of the imaging system with its function

1. positioning algorithm

positioning algorithm - improves image resolution by factoring in the output of each PMT to better localize the position of the photon interaction in the imaging field

match the part of the imaging system with its function

pulse height analyzer

accepts summed PMT output (Z-pulses) that correspond to the photon energy of the source

match the part of the imaging system with its function

gantry

supports the camera heads

match the part of the imaging system with its function

1. collimator

restricts photon entry to the crystal so that each point in the image corresponds to a unique point in the source

match the part of the imaging system with its function

crystal

converts photon energy to light energy

match the part of the imaging system with its function

Photomultiplier tube

converts light energy to a small electrical pulse

What is the pixel size for an image acquired with a field of view of size 32cm × 32cm and a matriz of size 128 × 128

2.5 × 2.5mm (320mm/128=2.5mm)

Connect the following events with the corresponding components of a scintillation detector

preamplifier

the output of the photomultiplier tube is amplified to more readily detectable level of current

Connect the following events with the corresponding components of a scintillation detector

crystal

light photons are released in response to gamma photons

Connect the following events with the corresponding components of a scintillation detector

photocathode surface of photomultiplier tube

photoelectrons are released in response to light photons

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

Compton peak or edge

maximum Compton electron energy

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

Iodine escape peak

can be seen at 28keV below the photpeak

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

annihilation peaks

can be seen at 511keV and1020keV below the photopeak of the high energy photon

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

Coincidence peak

peak near 420keV emitted by a In-111 source

Name the following features that can be seen in the energy spectrum obtained from a sodium iodide crystal detector

lead x-ray peak

72keV