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Medical Physics

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on 23 February 2015

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Transcript of Medical Physics

What is Medical Physics?
Medical Physics is the general application of physics in medicine and healthcare. This includes:
therapeutic radiological physics
diagnostic imaging
nuclear medicine physics
medical health physics (radiation protection).
production of images & treatment
uses longitudinal waves (sound waves)
high frequency (ranging from 20,000 Hz)
sound waves - vibrations that pass through materials
can transmit through different materials
Three-dimensional images
real-time imaging
multiple sets of transducers
done extremely quickly -> mother can watch unborn child's heartbeat
phase scanning
improved image detail
3-D imaging is made by compilation of 2-D imaging
Discovered in 1895 by Wilhelm Conrad Röntgen by accident
He was working on something else and somehow accidently produced an unknown "invisible" light or ray
X-radiation (X stands for unknown)
He found that the X-ray would pass through most substances, casting shadows of solid objects on pieces of film
Including the tissue of humans leaving the bones visible
Won the first Nobel Prize in Physics in 1901
Interesting Facts
Ultrasound of a Unborn Child
X-RAY Cont.
X-ray examinations are very common. Some uses include
fractures, dislocations, bone/joint condition/ chest conditions
As a surgical tool

used to help surgeons perform operations
Detection of foreign objects

eg. bullet fragments or swallowed objects

Medical Physics
Discovery of X-rays
Produce shadow-like images
Different absorption rates of different tissues.
Calcium in bones absorbs X-rays the most
bones look white
Fat and other soft tissues absorb less so they look grey
Air absorbs the least, so lungs look black
Reading Radiographs ( X-rays)
Producing Ultrasound
Doppler Scanning
can estimate your blood flow through blood vessels (how fast)
bounces high-frequency sound waves (ultrasound) off circulating red blood cells.
measuring the rate of change in its pitch (frequency).
takes at least 14 years for a radiologist to become fully qualified
Private paying individual:
CT scan - $50~$300
MRI scan - approx. $250
Ultrasound - depends on the type (can be $100~$1000)
By: Irene, Julia V., Melissa
Ultrasound Treatments
medscans.com.au. 2012. CT Scans - FAQ. [ONLINE] Available at: http://www.medscans.com.au/info/ct-info.html. [Accessed 23 March 14].
Injury Update. 2003. Cash price of an MRI scan. [ONLINE] Available at: http://www.injuryupdate.com.au/forum/showthread.php?450-Cash-price-of-an-MRI-scan. [Accessed 24 March 14].
Compare Ultrasound Cost. 2001. Ultrasound. [ONLINE] Available at: http://www.compareultrasoundcost.com/. [Accessed 25 March 14].
Fry, Burrows, Chapman, Bail, C.F, K.B, R.C, D.B, 2011. Heinemann Physics 11. 3rd ed. Australia: Ross Laman
Better Health Channel. 2001. X-Ray Examinations. [ONLINE] Available at: http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/X-ray_examinations?open. [Accessed 25 March 14].
About.com Inventors. 2001. X-Rays. [ONLINE] Available at: http://inventors.about.com/od/xyzstartinventions/a/x-ray.htm. [Accessed 25 March 14].
can be used to treat injuries and medical conditions
speeds up the process, reach deeper parts and heats up, low intensity waves
help lessen the pain and improve the overall function of the injury.
intensity increased- can kill cells
Ultrasound is safe to use as they is non-ionising radiation (hence used during pregnancy)
Types of X-Rays
Bone and Teeth X-Rays

( fractures, infections, arthritis, dental decay, bone cancer, etc.)
Chest X-Rays
(Breast Cancer, Lung Cancer, Blocked Blood Vessels, Enlarged hearts, etc)
Abdomen Problems
( Digestive Problems, etc )

Safety and Dangers
possible to calculate the velocity, frequency or wavelength of a wave if the other two values are known:
v = f
The velocity (v) is the speed of the wave (m/s)
The frequency (f) is the number of times a particle oscillates per second. (Hz.)
The wavelength () is the distance between two compressions or rarefactions. (m)

Frequency, velocity, wavelength
equipment for 3D imaging is expensive
2D image fulfill diagnostic requirements so 2D is mainly used
3D looks nicer though (if you have $)
regular ultrasound uses sound waves to produce images, but can't show blood flow.
may also help to check for injuries to your arteries or to monitor certain treatments to your veins and arteries.
blood clots
valve defects
congenital heart disease
Doppler Scanning cont.
- electromagnetic radiation
- used to create images of your internal organs or bones to help diagnose conditions or diseases
- can penetrate/pass through the human body
- deposits some energy into the body when passing through
- on an electromagnetic spectrum, x-rays come after ultraviolet but before gamma rays
What are X-rays
First X-Ray Experiment:
Film of Röntgen's wife's hand with a ring on her finger
CT Scans
Computer Tomography
main principles - same as x-rays
more detailed images BUT higher dose of radiation received
CT Scans are used for
viewing bone injuries
lung and chest problems
detecting cancers
MRI Scans
Magnetic Resonance Imaging
uses non-ionising radiation
safer than x-rays though more $$
can take unusual oblique c-s

MRI Scans are used for
examining soft tissue ligaments
tendon and spinal cord injuries
brain tumors
Both CT Scans and MRI Sans can produce cross-sections of the body
risk factor -exposed to radiation
Professionals have specialized training - using the smallest quantity of radiation needed to get the required results.
chance of increase of cancer (1 in million)
various radiation exposure
chest x-ray: 2.7 days of natural radiation
CT abdomen: 2.7 years of natural radiation

MRI Scan below,
CT Scan to right and
right bottom
computer does
majority of work
Full transcript