WORCESTER COLLEGE OF TECHNOLOGY

 

DEPARTMENT OF SCIENCE MATHEMATICS AND COMPUTING

 

BTEC Nationals in Applied Science

 

 

Unit Number: 21                        Unit Name: Medical Physics Techniques

Assignment Title:  Nuclear Medicine
Assignment No: 1 (of 4)

Launch Date	1st Submission Date	Return Date	Final Date

 

Description of unit

This unit develops knowledge and understanding of patient diagnostic and treatment techniques used in hospital medical physics departments.

It introduces the basic science necessary to understand the principles of the techniques used and develops this knowledge to explain the practical requirements of the procedures. It considers how the clinical information is obtained from the technique used and its suitability for particular investigations.

 

Introduction.

 

In Nuclear medicine radionuclides are injected into the blood stream and their passage through the body is followed using various detection instruments, one of the most important being the Gamma Camera.

Biochemical processes can be followed using a radioactive isotope of an element in the biochemical compound. For example, using radioactive iodine checks the uptake of iodine in the thyroid gland.

The quantity of tracer used must be as small as possible to minimise harmful ionising radiation. Exposure time is reduced if the substance that is labelled with a tracer is quickly eliminated from the body, or when the isotope has a short half-life.

The lifetime of the tracer must be matched to the time scale of any process being studied.

The best type of emission from the radionuclide is gamma radiation because gamma rays travel easily through matter and cause little ionisation. But low energy beta radiation is also useful.

 

Learning Outcomes

 

This assignment is an opportunity for you to demonstrate that you have learned about the following topics:

 

Radioactivity: basic atomic structure, and the characteristics of a, b, and g radiations; random nature of radioactive decay, half-life

 

Radionuclides: selection of radionuclides for particular applications; radionuclide generators and preparation of radiopharmaceuticals, the need for sterility and apyrogenicity

 

The gamma camera: main components and function of the g-camera as a detector; outline of quality control

 

 

Resource List:  Websites and Books

 

The web-site dedicated to this Unit is:

 

http://www.geocities.com/fizzsticks2000/plumpudding/ Find copies of assignments, links to relevant web sites, on-line materials to use in particular tasks.

 

For basic definitions of radioactivity try the following:

 

http://www.s-cool.co.uk/ The 's-cool' site. Quick notes on any GCSE and A-level subjects

 

http://hyperphysics.phy-astr.gsu.edu/hbase/hph.html The Hyperphysics Concepts web-site. Explore Physics by following through the concepts of Physics in clickable links.

http://www.lightandmatter.com/area1glossary.shtml a glossary of physics terms, with links to an on-line text book.

http://www.lhup.edu/~dsimanek/glossary.htm A Glossary of Frequently Misused or Misunderstood Physics Terms and Concepts, tells you what the words/terms DO NOT mean as well as what they do mean.

 

Books:  “Medical Physics: Imaging” by Jean Pope; “Nuclear Physics” by David Sang; other “Medical Physics” books in the Study Centre.

Assignment objectives.

 

Further information on completing assignments can be found in the Course Booklet. Of particular importance are the sections on “Late Submission” (page 16), “Extenuating Circumstances” (page 16) and “Plagiarism” (page 19)

 

Remember to fully reference all sources that you have used (see the Course Booklet for details on how to do this).

 

TASK 1: Different radionuclides, their properties and their uses

 

Investigate 5 different radionuclides that are used in medical procedures.

Say where you have searched for the information; say where you found the information; say what information you found.

Find out all you can about each radionuclides, for example: its half-life and its decay constant; how it is produced; what imaging it is used for (P4a); what radiation it emits; what properties make it desirable to use (M4a, M4b); its advantages and disadvantages (D4a, D4b) etc.

 

Write a paragraph on each radionuclide describing its characteristics.

 

Or

1. Construct and fill in a table of your findings similar to the following…

 

Radionuclide	halflife	Decay constant	How it is prepared…	Imaging uses…

(P4a)

2. If you discover enough information perhaps continue your table as follows…

 

Radionuclide	Desirable properties
	Biologically similar to…	Radiations emitted…	Time to clear from body…

(M4a, M4b)

3. And add even more columns if possible, eg…

 

Radionuclide	Dose used	Evaluation of radionuclide

(D4a, D4b)

…or, better yet, decide on your own column headings.

 

TASK 2: Preparation of a radiopharmaceutical

The most important radio-nuclide, used in 90% of examinations, is Technetium-99. It is rarely used on its own but is usually attached to a pharmaceutical to create a radiopharmaceutical.

 

1. Describe Tc-99’s atomic and nuclear structure (P1a)
2. Describe Tc-99’s radioactive decay: what is its parent nuclide, what is its daughter nuclide? (P1b)
3. Describe how a Tc-99 radiopharmaceutical is prepared for use and what quality control mechanisms are used (P4b, P4c)
4. Fing out the typical dose used of a Tc-99 radiopharmaceutical in a particular examination and so perform calculations (fully showing your working out) to show what initial activity of radiopharmaceutical would need to be gathered (D1, D4a)
5. Evaluate why Tc-99 is so commonly used: Is it its half-life? Its ease of production? Its ease of combination with suitable chemicals? Its emissions? Its emissions’ energy? Its cost? Its availability? What? (D4b)

 

 

 

 

TASK 3: Gamma Camera

 

1. Draw your own labelled diagram of a gamma camera that describes its main components and how it operates (P5a, P5b).
2. Describe how an image is produced and processed in the gamma camera. Describe how the different parts of a gamma camera perform their functions (M5).
3. Conduct an Internet search to investigate the differences between static and dynamic imaging using a gamma camera (D5a, D5b).

 

TASK 4: The random nature of radioactive decay or “Die-life”

 

Nitrogen-17 (N-17) is an unstable isotope of nitrogen that decays very quickly once formed (typical production: C-14 + a²⁺ à N-17 + p⁺).

Measurements tell us that N-17 has a half-life of 4.16 seconds and a decay constant of 0.1666 per second.

The decay constant tells you that a N-17 nucleus has a 16.66% chance of decaying every second. This is exactly the same chance as the chance of rolling a 6 with a six-sided die.

In this exercise you will use a six-sided die to investigate the life and death of N-17.

 

1. Get hold of a six-sided die and use it to try to find out for yourself the average life span of a N-17 nucleus.
2. Remembering that each roll of the die corresponds to 1 second of time. How many seconds does a N-17 nucleus live on average?
3. What range of life spans did you find for N-17?
4. How consistent are your results? How reliable do you feel that they are?
5. Does your investigations agree or disagree with the half-life of 4.16 seconds?
6. Get hold of a lot of dice to represent lots of N-17 nuclei. When you roll the dice what percentage of them would you expect to turn up 6? What percentage does turns up 6? Do you get different answers each time you roll? Does it matter how many dice you roll? If you have a large group of N-17 nuclei what percentage would you expect to decay every second? How confident can you be in your expectation?

 

Fully present and explain your findings and conclusions

(M1a, M1b)

 

 

 

 Grading criteria:

 

To achieve a pass grade you must show evidence that you are able to:

q       P1 describe basic atomic structure �P1a, radioactivity �P1b   q       P4 investigate and demonstrate a knowledge of a range of radionuclides �P4a, the preparation of a radiopharmaceutical �P4b and the quality control mechanisms necessary �P4c   q       P5 describe the main components �P5a and operating principles �P5b of the gamma camera

 

To achieve a merit grade you must show evidence that you are able to:

q       M1 appreciate the random nature of decay �M1a and how it relates to half-life �M1b   q       M4 understand the desirable biological �M4a and radiological �M4b properties of radionuclides used for imaging   q       M5 understand how the image is produced and processed �M5 in the gamma camera

 

To achieve a distinction grade you must show evidence that you are able to:

q       D1 perform calculations involving the half-life of radionuclides �D1   q       D4 understand dose requirements �D4a and evaluate the choice of radiopharmaceutical �D4b for a range of clinical imaging requirements   q       D5 understand image production for both static �D5a and dynamic �D5b imaging

 

Key Skills

 

This assignment provides the opportunity to demonstrate the following Key Skills:

 

Communication: C3.2, C3.3

 

Information Technology: IT3.1, IT3.2,  IT3.3