Nuclear medical systems use radioactive isotopes injected into the body to measure organ activity through radioactive decay detection. The key components are Geiger Muller tubes to detect beta particles, scintillation counters to measure gamma radiation intensity, rectilinear scanners that linearly scan detector collimators to obtain radioactivity graphs, and gamma ray cameras that use scintillation crystals and photomultiplier tubes to produce images of gamma ray interactions. Survey instruments are also used to monitor radiation levels. Together these components are used in applications like cancer detection, bone scans, and brain/neurological imaging and analysis.

1. Nuclear Medical Systems

2. Introduction
• Nuclear medical systems are used to count
radioactive decay from isotopes that have been
injected into the body in small amounts and taken up
by a target organ to measure its activity.
• Depending upon the radiation emitted by the
isotopes,a suitable detector is selected and operated
under optimum condition.
• Several methods are there for the detection and
measurements of radiation from radio nucleid.
Nuclear Medical System

3. Components
The basic components of a nuclear medical system are
• Geiger Muller Tube
• Scintillation Counter
• Rectilinear Scanner
• Gamma Ray Camera
• Survey Instrument

4. Geiger Muller Tube
• It is also called Geiger Muller Counter.
• It is radiation detector that counts the Beta particles.
• Beta particles cause a brief pulse of current.
• The total number of current pulses counted over a given period of time indicates
the radiation intensity.
Geiger Muller Tube

5. Scintillation Counter
• Scntillation crystal detector with photomultiplier tube measure Gamma radiation
intensity.
• When it detects,flashes of light produced and reflects onto the cathode of
photoamplifier tube.
• The current pulses produced for ray striking the fixed surface area of the detector
and are then counted to indicate the radiation intensity.
Scintillation counter

6. Rectilinear Scanner
A rectilinear scanner consist of
• Detector collimator
• Photomultiplier tube
• Amplifier
• Analyser
• Recorder

8. Detector collimator
• The detector motor assembly is driven by the scanner motor
assembly,scans back and forth in a linear manner.
• It typically uses a Na-I crystals to detect the radiation collimated
towards its surface.
• A graph of radio activity is obtain which indicates the amount of
radioactive isotopes taken up by the target organ.
• Improper amount indicates organ malfunction.
Photomultiplier Tube
• It intensify the signal.
Amplifier
• It amplifies the signal which was intensified by photomultiplier
tube.

9. Analyzer
• The pulse is analyzed by the analyzer for the comparisons
between successive events.
Recorder
There are two types of recorders are here.They are
• Dot scan recorder:- It produces a map of dots and dashes marks
on paper representing the distribution of radioactivity.
• Photographic recorder:-It produces a photograph of light flashes.
Note:-Recordings move simultaneously with the scanning device to
produce one line scan in unison.

10. Gamma Ray Camera
• It produces an image in a different manner than that of a
scanner.
• Gamma ray interact with large sodium iodide scintillation
crystal in the camera and the scintillations are observed
by an array of photomultiplier tube.
• Normally 19 tubes are used.
• A position analyzer evaluates the flashes from four crystal
quadrants.

11. • Flashes are produced on an oscilloscope display when
the gamma rays meet the pulse height analyzer
requirements.
• A polaroid or 35mm camera photographs the flashes on
the oscilloscope to produce a scintiphoto.
• Nearly 500,000 counts may accumulate for brain scans
on the CRT screen.

13. Survey Instruments
• Survey instruments are used to monitor radiation levels
where radioactive materials or other radiation sources are
present.
• It portable radiation detection instrument especially
adapted for inspecting an area or individual to establish
the existence and amount of radioactive material present.

14. Applications
• It is mainly used for cancer demonstartion or detection
and imaging.
• It is able to detect the minute bone cracks by doing the
bone scan.
• Used for the diagnostics of brain abnormalities.
• Used for the imaging of neuro receptors imaging with
specific radio marker molecules.
• For the analysis of the changes happend after the radio
therapeutic treatment is done.

15. Examples
Alzheimers analysis Nicotin content in neuro receptors analysis
Larynx cancer detection
Parkinson disease analysis

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