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Canadian Cancer Statistics 2013
Canadian Cancer Statistics 2013
Canadian Cancer Statistics 2013
Canadian Cancer Statistics 2013
Cancer in Canada
MONITORING ORGANS: Cancer
Why Use Imaging?
• non-invasive way of:
– Screening for cancer
• ex. mammograms for breast cancer
– Diagnosing/staging
• ex. location in the body, spread, guiding a biopsy
– Guiding cancer treatments
• ex. focus on the tumors and minimize damage to surrounding
tissue
– Determining if a treatment is working
– Monitoring for cancer recurrence
1. Ultrasounds
• Use of sound above human
hearing range to image body
structures, including soft
tissues
• Sounds waves are reflected
(echo) off of different density
tissues differently
2. X-Rays
• Oldest form of imaging
• Found by German physicist
Wilhelm Rontgen, 1895
• High-energy electromagnetic
waves that pass through soft
tissue (ex. muscle) but are
absorbed by dense tissue (ex.
bone)
• Can also be used to see soft tissues with the
help of stains (ex. bismuth)
Most popular use:
• Dental x-rays
An aside...
Electromagnetic radiation
- Forms of energy, some on the visible spectrum
(light)
• Some can be damaging to our DNA, in
particular high-energy high-frequency waves
(above colour spectrum)
3. CAT Scans: computerized axial
tomography scan
• An X-ray machine rotates around the patient
taking hundreds of individual pictures form
many angles
• More sensitive than an X-ray alone
• Computer re-assembles the picture into a 3-D
image, allowing for organs to be viewed
section-by-section
• Full body scans are still not routinely done due
to high incidence of “incidentalomas”, not real
issues that show up as issues on the scan
• Known to increase chances of cancer in
children…
4. MRI (Magnetic Resonance Imaging)
• uses radio waves and a strong magnet
• different tissues (including tumors) emit a more or
less intense signal based on their chemical makeup
• produces a three-dimensional images of sections of
the body
• MRI is sometimes more sensitive than CT scans for
distinguishing soft tissues.
• can use radioisotopes (unstable atoms) that
are injected into the target organ for imaging
5. PET (Positron Emission Tomography)
• used to locate a tumor
• the patient is given an injection of regular sugar
and a small amount of radioactively labeled
sugar
• because cancer cells take up sugar more than
other tissues in the body the tumor is easier to
find
• large amounts of radiolabelled sugar collect at
site of damage “lighting” it up
• PET scans are beginning to be used to check if a
treatment is working - if tumor cells are dying
they use less sugar