Nuclear Cardiology Board Review - copied from quiz

Electrons

negatively charged subatomic particles with very small mass

Protons

Positively charged particles with very high mass

Neutron

no electric charge with very high mass

outer electron shell

N

atomic number definition

the number of protons in the nucleus of an atom (determines the element)

atomic number letter

Z

Atomic mass

Number of protons and neutrons

atomic mass letter

A

equation for number of neutrons

mass number - atomic number (A-Z)

how to write an element

*** Isotopes

Atoms of the same element that have different numbers of neutrons.

*** isotopes - proton relationship

have the same number of protons

*** isotones

nuclides with the same number of neutrons (different elements)

*** Isobars

Nuclides with the same atomic mass (different elements)

*** isomers

nuclides in different excited/metastable states

What happens to binding energy of electrons as you move away from nucleus?

decreases

Which electron shell is closer to nucleus - K or L?

K (higher bound energy)

Define binding energy

Amount of energy that removes the electron in its shell

What is energy consequence of moving an electron from outer to inner shell?

Give off emission

What is the difference between gamma and xrays?

origin of the emission. Xray from outside the nucleus. Gamma from inside the nucleus

Where does gamma radiation come from?

Nucleus of an atom

Where does an xray come from?

outside the nucleus of an atom

What results in a characteristic xray?

an inner shell electron is ejected and its vacancy is filled by an electron from an outer shell

What is Auger effect?

Energy from filling an inner shell vacancy is transferred to another electron which is then ejected

this particle emission is worse for tissue than an xray

What forces are nucleons subject to?

coulombic and exchange forces

Describe metastable state

unstable but longer lived than excited state. called isomeric state

****What ratio determines the stability of nuclei? ****

The P/N ratio. if in proton or neutron rich zone emissions will occur

What is mode of of the mode of decay for Mo?

Beta emission with/without gamma

What is mode of decay for Tech 99m?

isomeric transition or internal conversation 99mTc to 99Tc

What is mode of decay for thallium?

Electron capture and gamma emission

Radioactive decay is spontaneous and random

More counts are better. more statistically sound

***What happens in Beta minus decay?

A neutron becomes a proton and an electron

***What happens to the Z number in beta minus decay?

it increases by one (changes elemental identity)

*** What kind of nucleus is likely to undergo beta minus decay?

neutron rich

***in beta minus decay what happens if the daughter is unstable?

it will emit a gamma ray

what is relationship between isomeric transition and internal conversion?

they are in competition

With longlived daughter isomeric transition occurs and gamma ray is emitted. if nucleus transfer energy to electron, conversion electron is emitted. What happens to technitium?

86% gamma emission

Tech 99m isomeric transition energy

140 keV gamma ray

What decay mode occurs in proton rich nuclei?

electron capture

What is electron capture?

orbital electron is captured by nucleus and combines with a proton to form a neutron

What happens to Z number in electron capture?

goes down by 1. element changes

How does thallium decay?

electron capture. gives off characteristic xray

The characteristic xray in thallium decay is characteristic of what element?

Mercury (Hg)

What type of nucleus can undergo positron emission?

proton rich nuclei

What happens in positron emission?

a proton becomes a neutron and a positron in emitted. there is no change is mass number but the atomic number will decrease by 1. the new element will be 1 to the left on the p. table

What happens to the positron?

it is annhilated along with electron. both are converted to energy

What is emitted in positron annihilation?

Two 511 keV photons (gamma rays) 180 degrees apart

What is the decay constant?

Lambda. average number of transitions per unit of time

Average decay of radioactive substance

dN/dT = -(lambda)N where N is the number of nuclei

What is a alpha particle?

helium nucleus (2 protons)

Alpha and beta particles lose energy through 3 collision types

1. Excitation

2. ionization (more energy)

3. Bremsstrahlung - most energy which is transferred to nucleus

What is excitation?

incident particle interacts with an outer shell electron.

energy is carried off by molecular vibration, infrared, visible or UV radiation

What is ionization?

an outer shell electron is ejected. The secondary electron (gamma ray) may cause ionizations.

You don't want this effect

Do higher mass particles travel farther or shorter distances?

Lose energy quickly and travel short path. Alpha is an example

Linear Energy Transfer (LET)

amount of energy deposited by radiation per unit length of tissue

photoelectric effect

100% energy conversion of a gamma ray to photoelectron

Spatially discrete

goal in nukes

Compton scatter

Compton scatter occurs when an incoming photon transfers only some of its energy to an outer shell e- or free electron which is ejected and the scattered photon (compton photon) changes direction. The compton photon has lower energy than the incident photon and is dependent on the compton angle (which is the angle of deflection). The compton (recoil) e- is ejected from the atom in a billiard ball fashion, the atom is ionized, and the ejected e- can interact with other atoms.

What is the third possible effect of interaction?

pair production

in photoelectric effect what is the secondary photon?

characteristic xray

in compton scatter what is the secondary photon?

scattered photon

What is the most likely interaction with photon with water for tech and thallium?

Compton effect

What is the most probable interaction in lead for thallium and tech photon?

photoelectric

Define half value thickness?

The thickness required to absorb half of the beam

What is the HVT of water for tech?

4.6 cm

Which of these are rector generated?

molybdenum

thallium

indium

molybdenum

Which of these are generated by cyclotron or linear accelerator?

\

molybdenum

thallium

indium

thallium and indium

68Zn (p, 2n) 67Ga

What is 68Zn called?

Target

68Zn (p, 2n) 67Ga

What is p?

the bombarding particle

68Zn (p, 2n) 67Ga

What is 2n?

The emitted particle

68Zn (p, 2n) 67Ga

What is 67Ga called?

product

Molybdenum is produced by nuclear fission from what element?

235U

absorption of a thermal neutron

breaks up into two similar atomic weight atoms

Neutron capture is an alterntive to fission. why not done?

less specific activity

What is the half-life of molbybdenum?

66 hours

Molybdenum generator allows once weekly delivery of a generator with daily access to tech

extract tech by simple column chromatography

99Mo/ 99mTc generator decay-growth characterized by what term?

Transient equilibrium

What comes out bottom of generator when saline is passed through the column?

sodium pertechnetate

Goal is 90% tech after elution. what are teh impurities?

99Mo

Alumina

Hydrolyzed reduced 99mTc (99mTcO2)

What is acceptable radiation of 131-I at time of injection?

0.05 microCi/mCi

What is acceptable 99Mo radiation at injection

0.15 microCi/mCi of tech

How do you detect 99Mo in eluate?

detect 740 and 780 keV photons usin dose calibrator

"Moly canister" stops the 140 keV photons of technetium

Alumimum breakthrouh in molly generator interferes with various radionuclides

What is an example of a radiochemical impurity in molly gen?

Free 99m-TcO4- - hydrolyzed 99mTc

what is the principal chemical imputiry in generator?

aluminum

Which tech preparation needs to be boiled?

Sestamibi

What is the reducing agent for tech?

stannous chloride

How is rubidium produced?

generator from Sr-82

secular equilibrium

generator lasts about 5 weeks

A dose callibrator is an example of what type of detector?

gas-filled

Two ion chamber gas filled detectors

dose callibrator

pocket dosimeter

Geiger-Mueller counter output is independent of enegy

yes or no on radiation

Scintillation detectors

Most common used in Nuc Med. Crystal of NaI doped with Tl produces numerous 2ndary electrons when an incoming photon is detected and produces visible light in response.

Four basic components of scintillation detectors

Scintillating material (NaI)

light detector (photomultiplier tube)

Voltage discriminator (pulse-height analyzer)

Display device (multichannel analyzer)

99mTc Sestamibi

Cardiolite

99mTc Tetrofosmin

Myoview

What happens to available perfusion tracers at high blood flow?

"roll off"

This can lead to underdiagnosing diease

Which of the available radiotracers show myocardial redistribution?

Thallium and Teboroxime

How soon after thallium can you image?

How long after sestamibi can you image?

15-60 minu

How long after Tetrofosmin?

15-30 mins

Why can you image tetrofosmin earlier than sestamibi?

less liver uptake

What is the energy of thallium photons?

69-81 keV