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NUCMED > Radiation Detection SYSTEM > Flashcards

Radiation Detection SYSTEM Flashcards

(57 cards)

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1
Q

– material that produces signal as a result of energy deposition
-Electrical Charge
• Light
• Chemically change molecules

A

Detector

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2
Q

– emission of visible light by inorganic crystals and some organic molecules

A

Radioluminescence

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3
Q

– measures absorbed dose or absorbed dose rate

A

Dosimeter

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4
Q
  • signal is proportional to energy of photon or particle
A

Spectrometer

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5
Q

– counts number of particles or photons interacting with
detector

A

Counter

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6
Q

2 types of Detectors

A

GAS FILLED DETECTORS
SCINTILLATION DETECTORS

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7
Q

___DETECTORS - those that depend on
excitation.

A

SCINTILLATION

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8
Q

DETECTORS - Those that depend on ionization in which ionization is translated into electric current or impulses

A

GAS FILLED

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9
Q

Detectors
➢ Radiation is sensed by detecting the ionization of gas
molecules produced by deposition of energy

A

Gas – Filled

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10
Q

One important approach to radiation detection is the use of an

A

ionization chamber.

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11
Q

. A ___ is created between two electrodes, but no current flows in the absence of exposure of the chamber to radiation

A

potential difference

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12
Q

Gas- Filled Detetors- Commonly used gases: ___, ___, ___, ___

A

Helium, Neon, Argon, and Hydrogen.

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13
Q

Gas – Filled Detectors
➢ The interaction of ionizing radiation with the gas in the chamber creates ___,&___, which move to the electrodes and produced
electrical curren

A

positive and negative ions

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14
Q

3 Types Of Gas-filled
Detectors

A
  1. Proportional Counters
  2. Ionization Chamber (IC)
  3. Gieger-Mueller Counters
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15
Q

•Are very sensitive type of personnel
monitoring device
•Provides an instantaneous reading, but must
be recalibrated daily
•Capable of only a predetermined range
•Resembles a fountain pen
•Inside the dosimeter is an ionization chamber
•Normally used only in emergency situation
(diagnostic) in which an immediate reading is
necessary

A

POCKET DOSIMETERS or Pen Dosimeter

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16
Q

(Gas-filled Detector)
❖ Used to determine the amount
of radioactivity in syringes or
vials

A

Dose Calibrator

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17
Q

do not have wide application in clinical nuclear medicine.
They are used in research to detect alpha and beta particles

A

Proportional Counters

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18
Q

One characteristic of proportional counters that makes them particularly useful is their ability to distinguish______

A

between alpha and beta radiation.

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19
Q

(Gas-filled Detector)
❖ an instrument for detecting and measuring the
intensity of ionizing radiation
❖ Used as a survey meter

A

Geiger-Mueller Counter

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20
Q

is used for contamination control in nuclear medicine laboratories. They are not particularly useful as dosimeters because they are
difficult to calibrate for varying condition of radiation.

A

Geiger counter

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21
Q

is one of the example of GM counter.

A

Survey meter

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22
Q

✓ When ionizing particles passthrough
certain crystals, flashes of light or
scintillation is emitted.
✓ The amount of light emitted is
proportional to the amount of energy
absorbed by the material.

A

Scintillation Detectors

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23
Q

This type of detectoris the most
commonly used detectorin nuclear
medicine.

Study These Flashcards
A

Scintillation Detectors

24
Q

Two Non-imaging devices They are based on the scintillator.
- Routinely used in the nuclear
medicine clinic

Study These Flashcards
A
  1. Well Counter
  2. thyroid probe
25
Consist of a NaI-crystal with a hole drilled on it. Measures very small amounts of radioactivity (kBq) Used for both radiation protection and clinical protocols Used to test for small amounts of removable radioactivity from working surfaces where radioactivity has been handled or from the sealed sources. (e,g. calibration sources
Well Counter
26
THYROID PROBE: Consist of a ___ on a stand with the associated counting electronics The patient is administered a small amount of ___. Probe: placed at a certain distance from the thyroid. Iodine Thyroid Uptake: can be estimated from the measurements.
NaI-crystal radioactive iodine
27
A special piece of equipment used to transform gamma rays into images that provide information about the function, primarily, and anatomy of the organ system being studied.
Gamma Camera
28
• A device capable of acquiring nuclear medicine images in various formats
Gamma Camera
29
• A device that uses the emission of light from a crystal struck by gamma rays to produce an image of distribution of radioactive material in a body organ.
Gamma Camera
30
Gamma Camera ___ Introduced by ___ Year:
Scintillation or Anger Camera Hal Anger (1958)
31
Gamma Camera System:
Collimator b. Scintillation crystals c. Light pipes d. Photomultiplier tube e. Pulse Height Analyzer
32
• Is an electronic device used to determine which portion of the detected spectrum is used to create images.
Pulse Height Analyzer(PHA)
33
Required to determine the directionality of the detected event. Defines the geometric field of view of the gamma camera crystal Used to confine the elements of a beam within an assigned solid angle Shielding device used to limit the angle of the entry of radiation.
Collimator
34
Collimator Composition: Location:
Lead (Pb) at the face of the detectors
35
4 types of collimator
Pinhole Multihole Parallel hole Converging multihole
36
The simplest form of collimator It consist of a single, small hole or aperture located a set distance (20 cm) from the surface. Image Magnification: a. Occurs if the objects are closer to the aperture. b. Important when imaging small objects with a large FOV
Pinhole
37
Pinhole Aperture diameter:
4-6 mm
38
Pinhole Spatial Resolution: determined by the ___ a. Diameter of aperture b. Distance from both of the object c. NaI crystal aperture
collimator
39
This type of collimator provides the best spatial resolution and the lowest sensitivity of any collimator used in nuclear medicine
Pinhole
40
Consist of a very large number of parallel holes with absorptive septa between holes. (limiting the amount of septal penetration to less than of 5%)
Multihole
41
Most commonly used type Provides substantiality better geometric sensitivity compared to the pinhole collimator because the object is viewed through many small holes.
Multihole
42
Hole of multihole shape
Hexagonal
43
Multihole Thinner septa: required for those collimators designed for low energy photons (<___ kEv)
200
44
No magnification occurs with this type of collimator Hole Diameter: 1mm Hole length: 20 mm
Parallel hole Collimator
45
Provides both enhanced spatial resolution and improved sensitivity. Used for imaging smaller objects (similar to pinhole) using a camera with a large FOV. Used to achieve magnified image with slightly improved spatial resolution
Converging Collimator
46
Scintillation crystals Most commonly used in gamma cameras.
Thallium activated Sodium Chloride (NaI) Crystal
47
is the most fragile component of the gamma camera
NaI
48
A sensitive element used to detect ionizing radiation by observing the emission of light photons induced in a material.
Scintillation detector
49
: the process in which some crystalline materials emit a large number of light photons upon absorption of ionizing radiation
Scintillation
50
Scintillate: to emit light ___
photons
51
” is the most important type of radiation detector used in nuclear medicine
scintillation detector/counter
52
A disk optically transparent material that helps direct photons from crystals into the PMT’s. • A tube-like structure attached to the scintillation crystals to convey the emitted light to the PMT.
LIGHT PIPE
53
Consist about 60-100 photomultiplier tube
Photomultiplier tube array
54
an electronic tube that convert light photons into electric pulses.
PMT
55
3 parts of PMT
1. Photocathode 2. Dynode 3. Anode (collecting anode
56
The main difference between a proportional counter and basic ionization chamber is greater applied voltage between ___
electrodes
57
is used for contamination control in nuclear medicine laboratories. They are not particularly useful as dosimeters because they are difficult to calibrate for varying condition of radiation
Geiger counter

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