1. Diploma in Applied Science
(Forensic Science)
UNIT 20 MEDICAL PHYSICS TECHNIQUES

2. Diploma in Applied Science (Forensic Science)
Unit 20 Medical physics techniques
Aims and purpose
The aim of this unit is to enable learners to develop, through a practical vocational skills
approach, an understanding of the important fundamental physics concepts behind medical
physics techniques such as x-rays, ultrasounds, diagnostic imaging and magnetic resonance
imaging (MRI) and radiotherapy. Learners will also understand the importance of radiation
safety.
Unit introduction
Diagnostic medicine has come a long way since the time when the best diagnosis occurred
during the postmortem examination. Surgery today is faster, less invasive and more effective
than ever – thanks in part to improvements in medical imaging technology. Imaging gives the
doctor a clearer understanding of the patient’s condition so treatment can be planned more
effectively and therapy delivered more precisely.
Nuclear medicine is providing hope for the cure of the most serious diseases, especially
cancer. Radioactive materials are used in this rapidly developing branch of medicine. At the
cutting edge of developments in nuclear medicine is the precise targeting needed to get the
radiation to the exact site of the cancer.
Future prospects are even more exciting. Medical imaging is extending human vision into the
very nature of disease; at the cellular level it will permit diagnosis before symptoms even
appear. Surgery in the future will be bloodless, painless and non-invasive. It will be powered
by medical imaging systems that focus on the disease and use energy to destroy the target
but preserve healthy tissue. Researchers are testing the use of high intensity ultrasound to
destroy tumours identified and targeted while the patient lies in an MRI scanner.
This unit introduces learners to some of the established practices in medical physics imaging.
It aims to deliver the underpinning knowledge of several of the fundamental techniques and
provide a basic introduction to the more complicated theory of magnetic resonance imaging.
Learning outcomes
On completion of this unit a learner should:
1. Know atomic structure and the physical principles of ionising radiation and ultrasound
2. Understand how radiopharmaceuticals are used in diagnostic imaging
3. Know the basic principles of magnetic resonance imaging
4. Understand the importance of radiation safety to the treatment of malignant disease
with radiotherapy.

3. Diploma in Applied Science (Forensic Science)
Task 1: Radiation and radioactivity
Your work as a junior technician in the radiography section of a large hospital involves
working closely with other highly qualified personnel, talking to patients undergoing
radiotherapy and periods of personal study. You must show that you have a clear
understanding of the terms used and an understanding of the basic science principles
involved in your department.
P1 Describe radioactivity, including atomic structure
P2 Describe the production of x-rays and ultrasound
M1 Explain the random nature of decay and how it relates to half-life
D1 Analyse the effects of the operation and design of the tube/head on a typical x-ray
spectrum
You need to complete the following task
• Draw sequences which show what happens to radioactive elements when they lose:
an alpha particle; a beta particle. What happens to an atom when gamma rays are
emitted? P1
• Draw a fully labeled diagram demonstrating the principles of: an X-ray tube; production
of ultrasound P2
• Using graph paper, show a decay curve and mark on: the axis showing the fraction of
undecayed nuclei remaining, the axis showing time, half-life intervals, fractions of
original number of undecayed nuclei remaining M1
• Use a suitable diagram to analyse what happens to the x-ray spectrum when the tube
voltage is changed. Show some known x-ray peaks in your diagram. What do these
peaks tell you. D1
Grading tips
Include labels of protons and neutrons in your answer and at least two element sequences for
each decay to achieve P1. To achieve M1 you could add a simple demonstration set of
results using dice to illustrate the random aspect.
Deadline:________28th January 2011________

5. Task 2: Radiopharmaceuticals and their uses
As a recent addition to the technical and nursing staff of a large city hospital, you must show
that you are familiar with the radiopharmaceuticals used and the way in which they are
detected within the body of a patient.
P3 Describe the production and detection of radiopharmaceuticals
P4 Explain the role of pharmaceuticals within the operating principles of the gamma camera
M2 Compare the desirable biological properties and radiological properties of radionuclides
used for imaging
D2 Evaluate the choice of radiopharmaceuticals for a range of clinical imaging requirements
You need to complete the following task:
• Make a list of the most common radiopharmaceuticals used in medicine, describe how
they are produced and briefly describe what happens when these substances enter the
body P3
• Explain how the gamma camera works using a fully labelled diagram P4
• Using your list for P3, provide details of what qualities you are looking for when
choosing a suitable radiopharmaceutical. Remember that patients have to inhale or be
injected with these substances M2
• Use information in this chapter (pg 374-377 Applied Science Level 3) and your own
research to evaluate which radiopharmaceutical are best for a given purpose D2
Grading tips
You should include the formulas for your radiopharmaceuticals in your answer for P3 and
what the images received by the gamma camera tells us for P4. Additional research is
necessary for M2 and D2, which should provide more information on the choices made by
doctors for particular radiopharmaceuticals in specific parts of the body. Health of the patient
is vital and the image produced is very important.
Deadline ________4th February 2011_________

6. Task 3: Investigating MRI
You are called upon to provide an explanation of the procedure of an MRI scan to a patient as
part of your duties as a technician within the radiology department of a major hospital.
P5 Outline the process of magnetic reasonance imaging including the instrumentation and
equipment used
M3 Explain the factors influencing signal intensity in MRI
D3 Evaluate the appearance of bone and soft tissue in an MRI scan and a conventional x-ray
You need to complete the following task
• Describe how the MRI scanner works in simple terms and list the components with a
brief description of each P5
• Provide an explanation of the principles of nuclear magnetic reasonance and how
difference factors change the signal intensity M3
• Use a variety of images of the same body parts to evaluate the similarities and
differences between x-ray and MR images D3
Grading tips
To achieve P6 your notes taken during the practical should be sufficient as long as they are
neat. Work through your maths carefully, keeping track of your units (if any) and prefixes. Get
them checked by friends, or tutors to get P7. To complete M3, a graph may help. Is the
chosen statistical method the most appropriate?
Deadline _______11th February 2011__________

7. Task 4: Radiotherapy techniques and their dangers
Working in the x-ray department of a busy hospital means that you will need to attend regular
specific additional training sessions for health and safety as part of your continued
professional development.
P6 Explain the principles and effects of radiation therapy including the equipment used
M4 Explain how excessive exposure to radiation can cause harm
D4 Evaluate a range of therapy techniques, types of radiation available and equipment used
You need to complete the following task
• Provide a slide demonstration explaining the way in which x-rays are used to treat
malignant disease. Provide a brief explanation of equipment which may be used P6
• Explain the physical effects of being exposed to a lot of radiation M4
• Evaluate the various types of radiotherapy practices that are currently in use and
explain the function of equipment that allows these kinds of treatment D4
Grading tips:
List the components of the equipment which focus x-rays onto the target with a simple
explanation of how they work and highlight what can happen to cells during radiotherapy for
P6. Link the doses of radiation to the symptoms of radiation exposure and comment on
preventative measures to achieve M4. You will need to include specific radiation types used
for particular diseases for D4 and the equipment used to produce and target the radiation.
Deadline _______18th February__________

8. Outline of evidence requirements
Assessment
Assessment Description Complete Assignment
criteria
Describe radioactivity, including
P1 20.1
atomic structure
Describe the production of x-rays
P2 20.1
and ultrasound
Explain the random nature of decay
M1 20.1
and how it relates to half-life
Analyse the effects of the operation
D1 and design of the tube/head on a 20.1
typical x-ray spectrum
Describe the production and
P3 20.2
detection of radiopharmaceuticals
Explain the role of pharmaceuticals
P4 within the operating principles of the 20.2
gamma camera
Compare the desirable biological
properties and radiological
M2 20.2
properties of radionuclides used for
imaging
Evaluate the choice of
D2 radiopharmaceuticals for a range of 20.2
clinical imaging requirements
Outline the process of magnetic
reasonance imaging including the
P5 20.3
instrumentation and equipment
used
Explain the factors influencing
M3 20.3
signal intensity in MRI
Evaluate the appearance of bone
D3 and soft tissue in an MRI scan and 20.3
a conventional x-ray
Explain the principles and effects of
P6 radiation therapy including the 20.4
equipment used
Explain how excessive exposure to
M4 20.4
radiation can cause harm
Evaluate a range of therapy
D4 techniques, types of radiation 20.4
available and equipment used