OCR LEVEL 2 CAMBRIDGE TECHNICALCERTIFICATE/DIPLOMA IN

SCIENCE

RADIOLOGYL/505/3125

LEVEL 2 UNIT 13

GUIDED LEARNING HOURS: 60

UNIT CREDIT VALUE: 10

TECHNICALSCambridge

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RADIOLOGYL/505/3125

LEVEL 2

AIM AND PURPOSE OF THE UNIT

Healthcare professionals regularly make use of a range of radiological techniques. A number of methods of studying the internal anatomy of a patient are used routinely and learners may have prior knowledge of some diagnostic uses of, for example, X-rays and ultrasound. They may, however, not be familiar with the full range of techniques that are available.

The aim of this unit is to increase understanding of the way in which different radiations can be used safely in a medical context. This will allow healthcare workers to become well informed about the techniques used. Consequently, they will be able to support and reassure patients who are being treated using, for example, X-rays and radioactive sources.

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Radiology Level 2 Unit 13

ASSESSMENT AND GRADING CRITERIA

Learning Outcome (LO)

The learner will:

Pass

The assessment criteria are the pass requirements for this unit.

The learner can:

Merit

To achieve a merit the evidence must show that, in addition to the pass criteria, the learner is able to:

Distinction

To achieve a distinction the evidence must show that, in addition to the pass and merit criteria, the learner is able to:

1 Know how X-rays are used by Diagnostic Radiographers.

P1 outline the main features of X-ray images

M1 explain how X-rays can be used diagnostically by a radiographer

P2 describe the use of fluoroscopy and angiography in the diagnosis of disease

M2 explain how fluoroscopy and angiography operate as a diagnostic technique

P3 describe how the images produced using computed tomography (CT scan) differ from those produced by normal radiography

M3 outline how X-ray computed tomography (CT scan) can be used to create a three-dimensional image of internal body structures

D1 describe the advantages and disadvantages of using Magnetic Resonance Imaging (MRI) as an alternative to other medical imaging techniques

2 Know how a Radiographer uses ultrasound to observe structures inside bodies.

P4 describe how ultrasound works and how it is used to produce an image of internal structures within the body

D2 explain how the time taken for reflection is used by a computer to determine internal structures within the body

3 Know that radioactive materials can be used for diagnosis and treatment by a Therapeutic Radiographer.

P5 describe how radioactive sources can be used as tracers

D3 justify the choice of tracer in terms of half-life and type of radiation

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Learning Outcome (LO)

The learner will:

Pass

The assessment criteria are the pass requirements for this unit.

The learner can:

Merit

To achieve a merit the evidence must show that, in addition to the pass criteria, the learner is able to:

Distinction

To achieve a distinction the evidence must show that, in addition to the pass and merit criteria, the learner is able to:

P6 Describe the advantages and disadvantages of the use of radiation in the treatment of cancer

M4 describe methods used to reduce risk to surrounding tissue when treating cancer

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TEACHING CONTENTThe unit content describes what has to be taught to ensure that learners are able to access the highest grade.

Anything which follows an i.e. details what must be taught as part of that area of content.

Anything which follows an e.g. is illustrative, it should be noted that where e.g. is used, learners must know and be able to apply relevant examples to their work though these do not need to be the same ones specified in the unit content.

LO1 Know how X-rays are used by Diagnostic Radiographers.

• Detection of X-rays - Historically X-rays were detected using photographic

plate or film, although modern systems use digital sensors.

- Areas where X-rays reach the detector are recorded on the sensor, as a different colour to those where no X-rays are detected.

• Absorption of X-rays - Different parts of the body absorb X-rays by varying

amounts e.g. bones absorb X-rays more than skin and muscle, gases do not absorb X-rays as much as body tissue, and the variation in absorption allows radiographs to be made.

- X-rays are absorbed by cells in the body.

• Diagnostic uses of X-rays - X-rays can be used to locate breaks in bones using

shadow images. - Interpretation of radiographs e.g. showing cracked and

broken bones and cavities in teeth. - Chest X-rays are used to identify lung disease such as

pneumonia and lung cancer.

• Fluoroscopy - This is a technique that is used to produce ‘real time’

moving images of the workings of the body’s internal structures.

- When X-rays strike a screen coated with a suitable chemical, the screen glows (fluoresces).

- A patient is placed between the source of the X-rays and a fluorecent screen to produce moving images of internal structures.

• Angiography - This is an adaptation of fluoroscopy that is used to

study the inside of blood vessels and the body’s organs. - Blood does not absorb X-rays well enough to form a

shadow, so a contrast agent that does absorb X-rays well has to be introduced into the blood stream.

- Contrast agents are often compounds of barium or iodine and have a range of commercial brand names.

- The image produced is called an angiogram and can be used by a radiologist to detect blockages in, narrowing of and bleeding from, blood vessels.

• Computed Tomography (CT scan) - In computed tomography, a large number of X-ray

images of ‘slices’of the body are made. - The large amount of data collected is processed by a

computer to produce a three-dimensional image of the body.

- The images are used to produce images of complex fractures, study head injuries and to diagnose abdominal diseases.

• Magnetic resonance imaging (MRI) - MRI techniques are used by radiographers to create

a two- or three-dimensional image of the internal structures of a patient’s body.

- Unlike CT scans, which expose patients to relatively high levels of potentially damaging X-rays, the MRI scan does not use any ionising radiation.

- The images of soft tissue produced by MRI are clearer than CT scans, making MRI a more useful technique for studying the brain or heart.

- CT scans are, however, usually more widely available, quicker to produce and less expensive.

LO2 Know how a Radiographer uses ultrasound to observe structures inside bodies.

• What is ultrasound? - Sound that cannot be heard by humans because it has

a pitch (frequency) that is too high. - The ear of a healthy young adult does not ‘hear’ sounds

with frequencies higher than approximately 20000 hertz (Hz).

- Ultrasound is produced by something vibrating more than 20000 times each second with a frequency of 20 kilohertz (kHz).

- Radiographers use ultrasound that has a frequency in the range 1 to 18 megahertz (MHz), 1 MHz = 1000 kHz.

• Echoes and their use in measuring distances - Sound can be reflected when it hits a solid surface and

an echo is heard.

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Radiology Level 2 Unit 13

- The time between making a sound and hearing the echo at the same place can be used to calculate the distance to a reflecting surface.

- Distance to reflecting surface = ½ speed of sound x time to hear the echo.

- The speed of sound is different in different materials.

• Ultrasonography - A probe which contains a device to generate

ultrasound and another to detect the ultrasound is moved across a patient’s skin.

- Whenever a sound wave hits the boundary between different materials, part of the wave is reflected back to the probe and is detected as an echo.

- The time it takes for the echo to return back to the probe is measured.

- This time is used to calculate the depth of the boundary.

- The strength of the reflected wave can be used to identify the type of materials that form the boundary.

- A computer is used to process the large amount of data collected to form an image showing the internal structure of the body.

- The technique has a wide range of uses, for example; monitoring the development of a foetus during pregnancy, studying internal organs such as the heart, and assisting with the insertion of needles to avoid contact with delicate parts of the body such as the nervous system.

LO3 Know that radioactive materials can be used for diagnosis and treatment by a Therapeutic Radiographer.

• Diagnosis - the use of radioisotopes as tracers - Tracers are specially prepared radioactive substances

that can be introduced into the body. - The journey of tracers around the body can be tracked

using a radiation detector that is placed outside the body.

- The behaviour of the isotopes can be used to identify specific conditions e.g. the function of the thyroid gland can be checked using a tracer; the thyroid absorbs all forms of iodine from the blood and a tracer containing a radioactive form of iodine is swallowed. Some time later a radiation detector is used to measure how much of the radioactive iodine has been absorbed and how evenly it is distributed in the thyroid, to check that the gland is working correctly.

• Treatment - the effect on cells of radiation from radioactive materials - Radioactive materials emit ionising radiation.

- The radiation can be absorbed by cells in the body. - Strong doses of radiation can be used to destroy cancer

cells. - The radiation can damage DNA in cells and

subsequently, cause cancer. - Cancerous cells can be destroyed using a radioactive

source that is positioned outside the body, with its radiation directed at the tumour.

- An alternative is to use a radioactive implant placed inside the body, either inside or close to a tumour.

• Choice of source for radiotherapy - When using radiotherapy, care has to be taken to

make sure that damage to the non-cancerous cells surrounding the tumour are minimised.

- Radioactive materials emit three different types of radiation; alpha, beta and gamma.

- Gamma and alpha radiation are absorbed by body tissues - alpha radiation is the least penetrating of the three types and is absorbed only by a few millimetres of body tissue, while gamma radiation is the most penetrating and will be absorbed significantly by body tissue.

- Some radioactive sources emit ionising radiation for longer than others.

- The half-life of a radioactive source indicates how long it takes for its activity to halve.

- A short half-life means that the level of radiation becomes safe relatively quickly.

- The source used for a tracer has to emit radiation that is able to penetrate tissue so that it can be detected outside the body but remain active long enough to allow the necessary measurements to be taken.

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DELIVERY GUIDANCE

LO1 Know how X-rays are used by Diagnostic Radiographers

This section of the unit could be introduced by learners researching the way in which X-rays were discovered. They could be given a copy of Rontgen’s image of his wife’s hand and asked to offer an explanation of why it looks as it does. This could be followed up with a visit to a hospital to look at the equipment that is used to produce radiographs, in a modern context. They could identify the roles played by the people who work in the X-ray department of a hospital. It may also be possible to look at the equipment used for CT and/or MRI scans. Learners could be shown or reminded that light forms a shadow when it is blocked by an object and relate this to the way in which a radiograph is made. Through observation of radiographs, of different body areas, learners could identify how radiographers and dentists use X-rays diagnostically in the identification of broken bones, cavities in teeth and disease in soft tissue.

Learners could research how X-rays can be used to create moving images of internal body structures (fluoroscopy) and describe situations in which this process is useful e.g. pinning bones with complex fractures. Learners could research how angiography is used to study the inside of blood vessels and organs of the body. Learners could be taught why a contrast agent must be introduced into the bloodstream and why moving images are of more use than still images. Learners could research the risks associated with exposure to X-rays and the way in which a patient is prepared for angiography. They could produce an information sheet that supports a nurse who is explaining to a patient why something has to be put into their bloodstream and the precautions that will be taken to minimise the risk to them.

To complete the section learners could research the way in which three-dimensional images of a patient’s body are produced by CT and MRI scanners. They could be directed to identify why using magnetic resonance imaging (MRI) is inherently safer than a X-ray computed tomography (CT scan) and consider the advantages of a CT scan in terms of speed, avaiability and cost.

LO2 Know how a Radiographer uses ultrasound to observe structures inside bodies.

This section could be introduced by using a signal generator, loudspeaker and frequency meter to measure the highest frequency of sound that can be heard by individual learners.

This could lead to a definition of ultrasound, as sound, with a frequency greater than 20kHz. Learners could do some research to find the range of frequencies used by radiographers.

Learners could design a demonstration to show that sound is reflected by a surface to create an echo. Standing a suitable distance away from the wall of a large building and bursting a balloon could be used to measure the distance from balloon to wall. Learners could measure the time elapsed before the echo is heard. They could then be given a value for the speed of sound in air (e.g. 330 m/s) and use the equation:- (distance to reflecting surface = ½ speed of sound x time to hear echo) to calculate the distance to the wall.

Learners could do research to find values for the speed of sound in different substances to identify that the speed of sound depends on the medium that it is travelling through. They could also be shown that ultrasound can be detected using a suitable transducer.

Learners could collect images of developing foetuses and research the way in which the images are formed. Learners could be encouraged to use the ideas they have developed, about the formation of echoes and how measuring the time to detect an echo, can be used to measure the distance to the reflecting surface. They could interview people who have experienced the use of ultrasound diagnostically to discover what is involved from a patient’s perspective. Learners could use their interviews to identify other ways in which ultrasound can be used diagnostically.

LO3 Know that radioactive materials can be used for diagnosis and treatment by a Therapeutic Radiographer

To introduce the idea that radioactive sources can be used as tracers, a radioactive source could be hidden in a dummy and its position located using a Geiger counter. Learners could be taught that the radioactive forms of elements that are found in the body, can be used to monitor processes that occur in the body. Learners could research a specific use of one of these radioisotopes, for example, how radioactive iodine can be used to check the function of the thyroid gland.

Learners could be introduced to the idea that there are risks associated with the use of radioactive sources and find out what the risks are at cellular level. This could develop into research as to why radioactive materials can be used, by a therapeutic radiographer, to treat tumours. Learners could be taught formally about the way in which an external source can

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Radiology Level 2 Unit 13

be used to destroy cancer cells inside the body. The use of an internal source implanted into or close to a tumour could also be taught formally.

A demonstration, showing the absorption of gamma, beta and alpha radiation could be given using radioactive sources, suitable absorbers and appropriate radiation detectors. This could lead to an appreciation of the different ways in which gamma and alpha radiation are absorbed by body tissue. Learners could use their observations to explain why a radiographer would choose gamma radiation to use externally and alpha radiation internally. They could also research how shielding can be used to protect people working with radioactive sources. Learners could also be taught why the source chosen as a tracer should emit radiation that can be detected outside the body.

Learners could be taught that some radioisotopes remain dangerously radioactive for longer than others and that the half-life is the time taken for the activity of the source to halve. They could deduce that sources with a long half-life remain active for longer than those with a short half-life and that, for example, after seven half-lives the activity will have fallen to less than 1% of its original activity. They could also identify some of the radioisotopes that are commonly used in nuclear medicine and find out their half-lives.

Learners could write to a local hospital or the NHS asking for information about the ways in which the harmful effects, on both patients and health care workers, of ionising radiation, are minimised.

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SUGGESTED ASSESSMENT SCENARIOS AND GUIDANCE ON ASSESSMENT

Criteria Assignment Scenario AssessmentLO1 Using X-rays Learners produce a report to

explain how X-rays can be used to produce still and moving images of bones and soft tissue, including an interpretation of what can be deduced from chest X-rays and radiographs of the skeleton. Learners can be given a list of key words to give some structure to their reports.

The assessment could be in the form of a PowerPoint presentation with suitable images included.

P1 The learner will include an explanation of why some parts of a radiograph are black and other parts are lighter in colour.

M1 The learner will explain that bones absorb X-rays and so they are shown as dark areas, because no radiation reaches the detector and that gaps in bones appear as lighter areas, so breaks in bones can be located. They will also explain how a chest X-ray would identify, for example, pneumonia.

P2 The pass grade is achieved when a learner’s report of their research shows knowledge that flouroscopy involves making moving X-ray images and that the inside of blood vessels can be studied.

M2 When a learner’s report of their research shows knowledge of how moving X-ray images can be made and describes two or more situations, one involving fluoroscopy and one involving angiography, in which this process is useful, the merit grade is achieved.

P3 A learner who describes a CT scan as producing a 3-D image will achieve the pass grade.

M3 To achieve the merit grade, the learner should show that they understand the way in which a 3-D image can be created by using a computer.

D1 A learner who provides a detailed and reasoned description of the advantages and disadvantages of MRI, in terms of, for example, clarity of images, cost and safety, achieves the distinction grade.

LO2 Foetal development

Learners could produce a leaflet to inform mothers-to-be how ultrasound will be used to produce images of their child before it is born.

P4 To achieve the pass grade, a learner’s leaflet should make it clear that ultrasound is reflected from surfaces within the body and that multiple reflections are analysed by a computer, to build up an image of the foetus.

D2 The learner’s leaflet will explain that the device moved across the skin contains an emitter and detector of ultrasound and that the time taken for a pulse of ultrasound to be reflected back to the point from where it was emitted is used, in combination with the time taken by many other pulses to be reflected, to calculate how far below the surface the reflecting surface is. They will also appreciate that a computer must be used to process the large amount of data involved.

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Radiology Level 2 Unit 13

LO3 Radioactivity in medicine

Learners research ways in which radioactive sources can be used as tracers and to treat cancer safely, including the selection of sources that emit the most appropriate type of radiation and have a suitable half life.

The assessment could be in the form of a report on the use of radioactive sources in hospitals to diagnose a specific condition and to treat tumours using internal and external techniques

P5 Research completed by the learner will show that the use of tracers, in a procedure, has been understood if the pass grade has been achieved.

D3 The learner should explain why a specific source is chosen in terms of its half life and the type of radiation that is emitted. When a learner explains that the half-life of a radioisotope, used as a tracer, should be chosen to ensure that the source remains active for no longer than is needed and that a gamma radiation emitter may be the best type to use, because little radiation is absorbed by the body’s tissue and it can be detected externally, a distinction grade is achieved.

P6 To achieve a pass grade the learner must identify that ionising radiation can damage healthy cells but that it can be used to destroy cancerous cells.

M4 A merit grade is achieved if the learner provides evidence that they understand that risks are minimised by stopping X-rays reaching parts of the body that do not need to be exposed and that the time of exposure is kept to a minimum.

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