What is Isobaric Transition?
Means that Mass did not Change
Ex: Beta emission, Positron emission and electron capture
What is Beta Positive Decay (positron emission)?
-Positron is released that runs into an electron and creates two 511 kEV photons in opposite directions.
How are tracers produced?
- Bombardment
2. Fission
How does a Nuclear Reactor Work?
- Use Neutrons to Bombard the Target element
- Must clean up the parent element
How does a cyclotron work?
- Use Charged aprticles to bombard the Target element
- Results in a transmutation (Carrier Free w/o cleanup)
How does fission work?
- Neutrons are fired into atoms which makes a bunch of elements
- Need to filter out the element you want.
What is Physical, biological and effective half life?
- Physicial: Time to break down into half
- Biological: Time to Excrete Half
- Effective: Takes into account physical and biological
What is the formula for effective half life?
1/Effective=1/Physical + 1/Biologiacal
How are sensitivity and resolution related in a collimator?
- Inverse relationship
- high sensitivity= more photon counts but worse spatial resolution
How do distance, Septal Length and collimator width affect sensitivity and resolution?
- Distance has no effect on sensitivity
- Distance Affects resolutions
- Longer Septal Length: Better Spatial resolution but worse sensitivity
- Wider Holes: Better Sensitivity, Worse spatial resolution
What does a pinhole collimator do?
- It Magnifies and Inverts the image
- Magnification is Pinhole to image/Pinhole to object
- Poor Sensitivity
How do converging and diverging collimators work?
- Converging Magnifies without inverting
- Diverging Minimizes
How does the scintillation Crystal affect sensitivity and spatial resolution?
-Thicker Crystal: Increases sensitivity, Decreases Resolution
What does the Photomultiplier tube do?
- Converts light to electric signal
- Records Location and Signal Intensity
- More PMTs= Better resolution
What is the pulse height analyzer?
-Signal sent from the PMT that gets filtered so only the photons you want are recorded
WHat is the concept behind down scatter?
-Need to always measure the LOWER photon element first, bc higher ones will have downscatter and the PHA cannot discriminete between target and Scatter
How do you test for Field Uniformity?
- Flood Testing: Can the camera produce a uniform image along the entire image.
- Limit is 2-5% nonuniformity (1% if SPECT)
- Extrinsic WITH collimator is performed Daily
- Intrinsic WITHOUT collimator is performed weekly
- Counts should be about 10 million
How do you test Energy Window?
- Use a symmetric window at peak energy
- Test Daily
How do you test for Image linearity and Spatial Resolution?
- Place lead bar phantons between CO sheet and collimator
- Test Weekly
How do you test for Center of Rotation?
- Place 5 Tc axis points along the axis of rotation, and they should be straight
- Test Monthly
What is a Sodium Iodine Well Counter?
- Small Gamma Camera with 1 PMT where you can put your sample to get a dose measurement.
- Not good for over 5000 counts/sec
- High Geometric Efficiency
- Good for Blood Samples, Urine Samples and Wipe Tests
What is a Geiger Mueller Counter?
- Gas Filled chamber that detects low levels of radiation
- Limit 100 mR/hr
- Too high of a dose–> Dead Zone
What is an Ion Chamber?
-Detects higher levels of radiation (0.1 to 100 R/hr)
What is the QA on the dose calibrator?
CLAG
- Consistency: DAILY, within 5% of computed activity
- Linearity: QUARTERLY, checking for accurate readouts over a range of activities
- Accuracy: INSTALLATION AND ANNUALLY, Checking for standard measurements of radiotracers compared to what the activity should be.
- Geometry: INSTALLATION AND MOVEMENT, Correction for different position and size
