I, II, and III.

II and III

I and III.

I and II.

only II.

For protons, it accounts for the fact that they can overcome the electrostatic repulsion within the nucleus.

It is equivalent to electron binding energy, but for the particles within the nucleus.

For a given nuclide it is dictated by the difference between the sum of the masses of protons, neutrons, and electrons and an atom’s actual mass (the mass defect).

. The average binding energy per nucleon varies with the particular nuclide, and accounts for the relative stability of atoms.

Radioactive decay leads to atoms with lower average binding energy per nucleon.

None of the other choices

Increasing the distance between the patient and the camera

Decreasing the length of the lead septa in the collimator

Increasing the distance between the lead septa in the collimator

Decreasing the thickness of the scintillation crystal

None of the others is false.

Coincidence detection in PET is used to determine the direction of travel of the two simultaneously emitted gamma photons, and hence to decide on which line of response the radioactivity occurs.

An uncertainty always exists as to the location of the positron decay due to the distance the positron travels before annihilating with an electron.

Random occurrences in which two different decays each contribute a photon that is detected within the same time window constitute a source of noise in PET imaging.

In PET imaging the attenuation factor for the pair of photons generated on a given line of response is independent of the location of the activity along that line of response.

It assumes a heterogeneous tissue in terms of attenuation, and a perfect collimator.

A(x, y, z) is the attenuation at location (x, y, z

The contribution from each location falls off as the square of the distance, and is attenuated by the material along the line between that location and the detector.

It assumes mono-energetic photons, which is a good assumption assuming a given nuclear decay.

All are true.

All are true.

Uses a series of dynodes at successively more positive voltage within the tube to create increasing numbers of cascading electrons from an initial few electrons.

. Uses a photocathode to generate electrons from incoming photons.

Is designed to be extremely sensitive to high energy photons, including gamma and x-ray photons.

Used in an Anger camera to produce an electrical signal whose pulse height is related to the number of light photons generated by a gamma event.

Only I.

I and II

I, II, and III

II and III

I and III

I, II, and III

II only

II and III

I and II

I and III

Only I.

I and II.

II and III.

I and III.

I, II, and III.

I and III.

II and III.

I, II, and III

Only I.

I and II.

I and III

I, II, and III

II and III

I and II

only II.

It assumes mono-energetic photons, which is a good assumption with positron decay

The effect of attenuation along a given line of response on the number of coincident detections is independent of where the positron decay occurs along the line of response.

It assumes no random coincidences at the 2 detectors from different positron decays.

All are true.

It assumes a heterogeneous tissue in terms of attenuation.

All of the others are true

They are generally the first step within a detector in using high-energy photons (X-ray or gamma) to create an image

Like fluorescence, lower energy photons are created from higher energy photons.

Unlike fluorescence, the higher energy photon causes ionization and many lower energy photons are formed from a single higher energy photon.

It occurs within the body providing a natural amplification of the number of useful high-energy photons reaching the detector

The contribution from Compton scattering to the image is reduced by analyzing the pulse height of the combined responses of the photomultiplier tubes to each detected gamma particle.

Each gamma particle produces a scintillation consisting of many light photons.

Multiple photomultiplier tubes are arranged in a grid behind a large crystal that act in concert to determine the location of the incoming photons with a spatial resolution greater than that of the tubes

Individual gamma photons are counted and located.

Lead septa are not required to generate a projection image.

The primarily physiological, higher-resolution information from the CT scanner is combined with the primarily anatomical, lower-resolution information from the PET scanner.

Virtually every PET scanner sold today also contains a CT scanner.

Registration of the two imaging modalities is greatly facilitated since the patient only needs to be slid a short distance between the actual scanners.

The CT scanner is used to determine the attenuation along each Line of Response in the PET scanner

All are true