Overview revision for year 11 physics Medical imaging key knowledge.

1. •Overview of various medical imaging/
treatment techniques
•Quiz
•Electricity

2. Why use medical imaging

3. Medical Imaging/treatment
 Radiation
 Diagnostic X-ray, CT (Computed
Tomography), PET (Positron Emission
Tomography), LINEAC (Linear Accelerator)
 Non-ionising
 MRI (Magnetic Resonance Imaging),
Ultrasound/Sonography (Sound wave),
Endoscope (light)

4. X-ray Machines

5. X-ray machines –
X-ray Photon Energy

6. X-ray machines – Anode
 Tungsten  High melting point
 Hi Atomic number  High-conducting
ability

7. X-ray machines – Anode
•A target for high-voltage electrons from the filament; thereby
becoming the source of the x-ray photons.
•Conducts the high voltage from the Cathode back into the
circuit.

8. X-ray machines – Anode
•The purpose of the cathode is to conduct a high voltage to
gap between cathode and anode.
•Flow of electrons from cathode to anode.

9. X-ray machines – Anode
 Tungsten – is the target surface is
where the high speed electrons are
attracted from the filament are suddenly
stopped.
 Braking radiation" or "deceleration
radiation"

10. X-ray machines – X-ray
production
 X rays are produced by 2 forms of
electron interaction with the tungsten
target.
Bremsstrahlung Characteristic Photons

11. X-ray machine - Filtration
 The bremsstrahlung photons generated within
the target material are attenuated as they pass
through typically 50 microns of target material.
The beam is further attenuated by the
aluminum or beryllium vacuum window.
 The results are an elimination of the low
energy photons, 1 keV through l5 keV, and a
significant reduction in the portion of the
spectrum from 15 keV through 50 keV. The
spectrum from an x-ray tube is further modified
by the filtration caused by the selection of
filters used in the setup.

12. X-ray machines – Image

13. X-ray machines – Image

14. X-ray machines – Image

15. CT (Computed Tomography)
Computed axial tomography (CAT)
Digital geometry processing is used to
generate a three-dimensional image of
the inside of an object from a large
series of two-dimensional X-ray
images taken around a single axis of
rotation

16. CT (Computed Tomography)
Tomography Digital geometry
processing is used to generate a
three-dimensional image of the inside
of an object from a large series of two-
dimensional X-ray images taken
around a single axis of rotation

17. Tomography Reconstruction

18. PET (Positron Emission Tomography)
The system detects pairs of
gamma rays emitted indirectly by
a positron-emitting radionuclide

19. PET (Positron Emission Tomography)
When a positron is emitted by a
nucleus, it almost instantly finds an
electron and the pair annihilates,
converting all the mass energy of
the two particles into two gamma
rays each at 511kev. The two
gamma ray photons possess
momentum, and the conservation of
momentum requires that they travel
if opposite directions. A
simultaneous detection of gamma
ray photons in two detectors places
the source on a line between those
detectors.

20. PET (Positron Emission Tomography)

21. PET (Positron Emission Tomography)
Radionuclide, placed on a
chemical - glucose.
Patient fasts for 12 hours so body
is starved from energy.
When injected glucose will
concentrate to more active cells,
as patient lying still glucose will to
cancer cell. Cancer cells are more
active than normal cells as they
are rapidly dividing.

22. PET (Positron Emission Tomography)
Fuse PET scan with CT scan.
Some PET scanners have CT
scanners also

23. PET (Positron Emission Tomography)

24. Ultrasound/ Sonography
Diagnostic imaging technique used
for visualizing subcutaneous body
structures including tendons,
muscles, joints, vessels and internal
organs for possible pathology or
lesions
Uses sound waves to
produce an image

25. Doppler effect
The received frequency is higher (compared to
the emitted frequency) during the approach, it is
identical at the instant of passing by, and it is
lower during the recession.
Is the change in frequency of a wave for an
observer moving relative to the source of the
wave.

26. Doppler effect

27. MRI (Magnetic Resonance Imaging)
Medical imaging to visualize
detailed internal structures. MRI
makes use of the property of
nuclear magnetic resonance (NMR)
to image nuclei of atoms inside the
body.
Uses the varying
magnetic properties of
atoms to produce an
image

28. MRI (Magnetic Resonance Imaging)

29. MRI (Magnetic Resonance Imaging)

30. Endoscopy
Means looking inside
Typically refers to looking inside the body
for medical reasons using an endoscope

31. Endoscopy
igid Endoscope is solid
metal tube with a series of
lens inserted in the tube
lexible Endoscope, the
principle optical component
is either a plastic or glass
fibre bundle for delivery of
the image, plus additional
fibres for the light.

32. X-ray Quiz
1. Name 2 types of imaging techniques
that use radiation and 2 that don't.
2. When a patient is due to undergo a
PET scan they are injected with a
radionuclide. What is emitted from the
radionuclide? What reaction takes
place after?
3. How does a CT scan obtain an image
that is a slice?

33. X-ray Quiz
1.Name the device used to obtain the
images.
A B
C D

34. X-ray Quiz
1. Ultrasound work below human hearing
frequency T/F?
2. PET scan are a relatively quick procedure
T/F?
3. Ultrasound cannot travel through 2
mediums in the body what are they?
4. There are white area black areas on an X-
ray image are showing variation in what?
5. What is the main principal behind an MRI
machine and the subject being
investigated?

35. X-ray Quiz
 Organise these in terms of flow from
electron source to X-ray. Start to finish.
Key terminology
Characteristic Photon, Patient, Anode,
Tungsten Target, Film, Filament,
Cathode, Bremsstrahlung, Scatter Filter,
Casset.

36. X-ray Quiz
1. Cathode,
1. Filament,
2. Tungsten Target,
2. Anode,
3. Bremsstrahlung, Characteristic Photons,
4. Patient,
5. Scatter Filter,
6. Cassette,
7. Film.

37. Thank You