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  1. 1. Senior Science Medical Technology – Bionics SECTION 5Non-invasive andminimally invasivemedical techniques
  2. 2. SECTION 5 Non-invasive & minimally invasive medical techniques 9.3.5 The use of non-invasive or minimally invasive medical techniques has greatly reduced risks to patients and has increased our understanding of how the body works9.3.5.a Discuss the terms non-invasive and minimally invasive in relation to medical techniques9.3.5.b Identify non-invasive diagnostic techniques including X-rays, ultrasound, thermography and magnetic resonance imaging (MRI) and discuss their importance in diagnostic medicine9.3.5.c Describe the advantages of using minimally invasive surgery techniques such as key hole surgery9.3.5.i Identify data sources, gather, process, analyse and present information to discuss the advantages and disadvantages of non-invasive and minimally invasive medical techniques© P Wilkinson 2002-04 2
  3. 3. 9.3.5.a Discuss the terms non-invasive and minimally invasive in relation to medical techniquesNon-invasive and invasive medical techniquesIn “Western” medicine, doctors use their sense organs to diagnose illnesses. They look forvarious indicators of poor health. Such indicators include: the colour of the skin and tongue,the smell of a person’s breath, skin temperature, pulse rate and the position of painful areason the body. Most people understand that a high body temperature or a pale skin can be anindicator of sickness. An important skill for a doctor is to interpret the health of the patientusing such indicators.For thousands of years, diagnosis of disease relied on using external signs to determine thehealth of the patient. The inside of the body was a mystery. It is believed that the innerworkings of the human body only began when some doctors began dissecting and studyingstolen corpses. This occurred during the 16th century.Diagnosis using external signs is a non-invasive medical technique because there is nopenetration of the skin and no damage is done to tissue. Today, diagnosis is aided by ahost of tests and technologies. Medical laboratories can take tests of blood, urine and otherbody fluids. In other situations, tissue samples might be taken and examined. All thesediagnostic aids give doctors vital information about the health of the patient with littleinconvenience to the patient. The procedures require no surgery and cause little or no pain.A powerful tool used in modern diagnosis is the various imaging techniques. They provideimages (pictures) of internal parts of the body. Imaging technologies began with the use of X-rays to identify problems with bones. Today • X-rays (CAT scans), • Ultrasound techniques, • Thermal imaging and • Magnetic Resonance Imaging (MRI),are all useful imaging techniques. These techniques are regarded as non-invasive. Theyallow the doctor to look inside the patient, without cutting through the skin and withoutdamaging underlying tissue. Many of these technologies depend on computers to helpcreate accurate images of the internal workings of the body.After a doctor makes a diagnosis, treatment can proceed. Treatment may includeprescription of medicine or surgery or a host of other methods. Surgery is branch of medicinethat is concerned with the treatment of injuries, diseases, and other disorders by manual andinstrumental means (operations). Many surgical techniques are highly invasive. They involvethe use of anaesthesia to deaden the pain or even “put the patient to sleep” as well as largecuts into the person’s body. Skin, tissue, nerves and blood vessels are all damagedduring invasive surgery. Such surgery involves major trauma for the patient, with longhospital stays and significant risk of wound infection.© P Wilkinson 2002-04 3
  4. 4. Modern technology has resulted in the development of minimally invasive surgery. In thiscase the incisions into the body are very small and involve minimal trauma to the patient - atypical example is keyhole surgery.Questions1. a. Identify two ‘external signs’ that indicate poor health. b. Explain why one of these external signs is non-invasive.2. Why would a doctor order a blood or urine test?3. What is the purpose of imaging technology?4. Name two ‘imaging’ techniques.5. Explain why MRI is a non-invasive technique.6. Define surgery.7. What happens to a patient during an invasive medical procedure?8. Consider the following list of medical techniques or procedures i. Taking a person’s rectal temperature ii. Taking a blood sample (using a syringe) iii. Viewing a foetus using ultrasound iv. Checking a person’s heart rate using a stethoscope. v. Using a laser to correct eyesight vi. Extracting a tooth vii. Angioplasty a. Put them in order beginning with least invasive to most invasive. b. Suggest which of these techniques are non-invasive and which are minimally invasive.  Put the information into a table (similar to the one shown below). Non-invasive Minimally invasive  Justify your decision to classify particular techniques.© P Wilkinson 2002-04 4
  5. 5. 9.3.5.c Describe the advantages of using minimally invasive surgery techniques such as key hole surgeryMinimal Invasive SurgeryTraditional open surgical techniques are being replaced by new technology in which a smallincision is made. This surgery has been termed key-hole surgery because entry into the bodyoccurs through a very small (key) hole.The procedure involves inserting an instrument called an endoscope into the body. Theseare small tubes containing a series of lenses and optic fibre bundles. They are fitted with alight source and small video cameras and range in size from about 2 – 5 millimetres indiameter. This allows doctors to see internal tissues and organs on a TV monitor. Additionaltiny cuts can be made if surgical instruments such as forceps and scissors are needed in theprocedure.Diagram of an endoscopeKey hole surgery is a minimally invasive surgical procedure because it requires a muchsmaller incision than traditional surgery does. This causes less damage to nerves, muscles,and skin. As a consequence the benefits include less pain, scarring and recovery time for thepatient (fewer days in hospital), as well as reduced health-care costs. It can be performedusing only local anaesthesia and a mild sedative.The technique now has many uses. It is used for diagnosis and in a variety of surgeries,including the repair of cartilage damage to knees, the removal of the gall bladder and inappendectomy, hysterectomy, repair of hernias, and removal of cancerous tumours.Questions9. Describe an endoscope.10. What is the difference between key hole surgery and traditional surgery?11. Why would key hole surgery be referred to as a minimally invasive technique?12. Name three advantages (benefits) of key hole surgery (for the patient).13. Name five uses of key hole technique.© P Wilkinson 2002-04 5
  6. 6. 9.3.5.b Identify non-invasive diagnostic techniques including X-rays, ultrasound, thermography and magnetic resonance imaging (MRI) and discuss their importance in diagnostic medicineDiagnosisHealth care consists of three main steps: ♠ Diagnosis ♠ Treatment and ♠ PreventionDiagnosis is the examination of a person to identify the injury or disease. The correctdiagnosis is important for the correct treatment of the injury or disease. A doctor makes adiagnosis by using a person’s case history, by physical examination and by medical tests.The case history involves the patient responding to questions about present and pastillnesses, family history of disease, and habits. The physical examination involves suchthings as measurement of height and weight, taking blood pressure, listening to the heart andlungs with a stethoscope. Examining eyes, ears, and mouth, testing hearing and vision mayalso be performed in routine physical examinations. Body fluids (blood, urine and spinalfluids) all reveal important information about disease.Today, there is an enormous array of medical tests. These include a host of imagingtechniques that are important in diagnostic medicine.Questions14. What is a medical diagnosis?15. Describe how does a doctor make a diagnosis?X-RaysX-rays are high-energy electromagnetic waves with a short wavelength. They have manysimilarities to visible light. Light has a lower energy. Because X-rays have high energy theycan penetrate deeply into many substances that do not transmit light. This penetrating powerof X-rays makes them extremely useful in medicine and industry. Pictures of internal parts ofthe body are possible because the X-ray radiation passes through the body. The rays areabsorbed more by dense tissue, like bones. The pictures produced are lighter or darkerdepending on the type of tissue the rays pass through.Advantages In medicine, X-rays are important because they provide pictures ofbones and internal organs of the body. X-rays help doctors detect problems such asbroken bones and lung disease. Dentists use X-ray pictures to reveal cavities. Today X-raysare the most widely used images in medical diagnosis. This is because they are cheapand the machines are widely available.© P Wilkinson 2002-04 6
  7. 7. Disadvantages Some limitations of using X-ray imaging are that the picture is only two-dimensional. Although at times the image is difficult to interpret, many X-ray images showeasily identified problems. Also, they cannot show structures deep within a tissue. X-raysactually pass through the body. Possibly, the biggest problem with X-rays is that they candamage, or even destroy, healthy tissue. This makes them very dangerous. Over exposureto X-rays can cause cancer and skin burns. The amount of exposure to X-rays needs to belimited.Activity 1Obtain several X-raysa. Observe the images andb. Describe what can be seen.Questions16. What is an X-ray?17. Why can X-rays be used to obtain pictures of internal parts of the body?18. What sorts of tissue or problems can be ‘viewed’ by X-rays?19. Explain why X-rays are important in diagnostic medicine.20. Explain why X-rays are widely used for diagnosis.21. What is the biggest problem with the use of X-rays in examining a patient?22. An X-ray can give a doctor a clearer view of a broken arm. To obtain such a picture, X-ray radiation passes through a person’s arm. Complete the two sentences below  An X-ray is a non-invasive technique because ………….  An X-ray is a minimally invasive technique because …………..23. Identify two limitations of using X-rays for diagnosis.24. Explain why it is relatively easy it is to interpret an X-rayX-rays and CAT scansThe use of computers has greatly improved imaging technologies. These new technologiescan now produce cross-sectional images. Unfortunately, compared to traditional X-rayimages CAT scan technology is quite expensive. They also require more skill andtraining to interpret the images.A CAT (computerized axial tomography) scan uses X-rays to produce an image. A thin ray ofX-rays is passed through the body at various positions. The rays that pass through the bodyare measured and the information is sent to a computer. The computer analyses the dataand cross sectional images are produced. The images produced are much clearer thannormal X-ray films. A series of CAT scan images allows the changes in organs as they work,to be viewed (for example the flow of blood through blood vessels can be viewed).© P Wilkinson 2002-04 7
  8. 8. Activity 2Observe some pictures made from CAT scans.Describe the difference between a cross-section image of a CAT scan and the imageproduced by an X-ray.Questions25. Outline some advantages of a CAT scan compared to a traditional X-ray?26. Outline some disadvantages of a CAT scan compared to a traditional X-ray?UltrasoundUltrasound is sound with frequencies in a range too high for humans to hear. This isgenerally regarded above a frequency of 20,000Hz (gycles per second – Hertz). Scientistshave developed a diagnostic and therapeutic technique using ultrasound.Ultrasound devices work because ultrasound is easily reflected. The ultrasound device isused to transmit sound and receive echoes. A jelly-like substance is smeared on the skin inorder to improve the acoustics. In the body various tissues reflect the sound. A computerprocesses the resulting pattern of sound reflection. A moving image can be produced on ascreen or on photographic film.Diagnostic Applications Air, bone, and other calcified tissues, absorb nearly all theultrasound beam, so this technique is of no use in determining conditions of the bones orlungs. However, as fluid conducts the ultrasound well, it is a useful technique for examiningstructures that are fluid filled.Ultrasound can be used to examine the arteries, the heart, the pancreas, the urinary tract, theovaries, the veins, the brain; and the spinal cord. When ultrasound is used to examine theheart, it is known as an echocardiography. Echocardiography is used to study heart disease,coronary artery disease, tumours of the heart, and other heart disorders.Use of Ultrasound in Pregnancy The best-known application of ultrasound is theexamination of the foetus during pregnancy. Unlike X-rays, ultrasound is completely safeduring pregnancy, with no risk to either mother or baby. It is also non-invasive, accurate anda cost-effective investigation of the foetus. It is used to monitor the growth, development, andwell being of the foetus, and can be used to check the due date. The size of the foetus’ headcan be measured to estimate its age. It can be used to detect foetal abnormalities such asspina bifida, or severe congenital heart disease; where in each case early diagnosis allowstreatment to be given during the rest of pregnancy and at birth.© P Wilkinson 2002-04 8
  9. 9. Questions27. What is an ultrasound?28. Explain how ultrasound imaging works.29. Name a tissue that cannot be examined by ultrasound.30. Name three internal structures that can be examined by ultrasound.31. Name three advantages of using ultrasound as a diagnostic technique.32. What type of radiation passes through the body during an examination by ultrasound?33. Explain why ultrasound is a non-invasive technique (refer back to previous information).MAGNETIC RESONANCE IMAGING (MRI)One of the newest, most expensive, yet most powerful types of imaging is MRI (MagneticResonance Imaging).The Basic Idea A MRI machine uses the water in the body, a powerful magnetic field andbursts of radio waves to create an image. The machine itself looks like a tunnel passingthrough a large cube. The cube in a typical system might be 2 metres tall by 2 metres wideby 3 metres long (although new models are rapidly shrinking). The patient goes into thetunnel head or feet first, depending on the examination needed.The MRI scanner can pick out a very small point inside the patient’s body and ask it,essentially, “what type of tissue are you?” The point might be a cube that is half a millimetreon each side. The MRI system goes through the patient’s body point by point, building up a2-D or 3-D map of tissue types. A powerful computer then joins all of this information tocreate 2-D images of 3-D models. MRI provides images of extraordinary detail compared toany other imaging process.Advantages and Disadvantages Why would a doctor order a MRI? Because the onlyway to see inside your body any better is to cut you open. MRI is ideal for:• Visualizing blood flow in virtually any part of the body. This allows images of the arterial system in the body, but not the tissue around it.• Diagnosing MS (multiple sclerosis)• Diagnosing tumours of the pituitary gland and brain• Diagnosing infections in the brain, spine or joints• Visualizing torn ligaments in the wrist, knee and ankle• Diagnosing tendonitis• Evaluating masses in the soft tissues of the body• Evaluating bone tumours, cysts and bulging or herniated discs in the spine• Diagnosing strokes in their earliest stagesThese are but a few of the many reasons to perform a MRI scan.© P Wilkinson 2002-04 9
  10. 10. MRI systems do not use ionising radiation (X-rays) that can damage living tissue. Also MRIcontrast materials have a very low incidence of side effects. Another major advantage forMRI is its ability to image in any plane. CAT is limited to one plane, the axial plane (ie using aloaf of bread analogy, the axial plane would be how a loaf of bread is normally sliced). A MRIsystem can create axial images as well as images in the sagittal plane (slicing bread side toside lengthwise) and coronally (think of the layers of a layer cake) or any degree in between,without the patient ever moving. If you have ever had an X-ray, you know that every timethey take a different picture, you have to move.MRI does have drawbacks, however. For example:• There are many people who cannot safely be scanned with MRI (for example, because they have pacemakers).• Orthopaedic hardware (screws, plates, artificial joints, etc…) in the area of a scan can cause distortions on the images.• MRI scans require patients to hold very still for extended periods of time. MRI exams can range in length from 20 minutes to 90 minutes or more. Even very slight movement of the part we are scanning can cause very distorted images that will have to be repeated.• There are many claustrophobic patients in the world, and being in a MRI machine can be a very disconcerting experience for them.• The machine makes a tremendous amount of noise during a scan. The noise sounds like a continual, rapid hammering. Patients are given earplugs or stereo headphones to muffle the noise (in most MRI centers you can even bring your own cassette or CD to listen to).• MRI systems are very, very expensive to purchase and therefore the exams are also very expensive.• Interpretation of MRI images requires specialised training.The almost limitless benefits of MRI for most patients far outweigh the few drawbacks.Questions34. What type of radiation passes through the body during an MRI examination?35. What technology is needed to process data collected by an MRI scanner?36. Describe how an MRI scan works.37. Research What is a tumour?38. Name three uses of an MRI scan, in diagnostic medicine.39. Explain why MRI scans have significant advantages over other imaging systems.40. Explain why an MRI scan is a non-invasive technique.41. Name two significant disadvantages of MRI scanning technology.© P Wilkinson 2002-04 10
  11. 11. 9.3.5.i Identify data sources, gather, process, analyse and present information to discuss the advantages and disadvantages of non-invasive and minimally invasive medical techniquesResearch Assignment ThermographyThermology is the study of heat. Thermography is a technique that uses differences in bodytemperature to create images. It is one example of a non-invasive medical technique usedtoday. Thermography uses infra-red radiation to see inside the body. Infra red cameras areused to detect the heat emissions from a subject. Computers are then used to analyse thedata collected to create colour images of the area being examined.Blood flow and the amount of metabolic activity affect body temperature. The technique isuseful to detect cancerous tumours because these tumours are metabolically very active. Itcan also be used to locate areas of increased or decreased blood flow.What to do Part A Diagnosis by thermography1. Access one of the following web sites2. Complete the task for that web site  Breast cancer can be diagnosed by thermography. Use the following web site and describe how thermography is used to diagnose breast cancer. http://home.earthlink.net/~docbill/athand.htm  Research is being constantly done in the area of thermography and its uses. Use the following web site and describe 3 recent discoveries or techniques that use thermography. http://www.thermology.com/research.htmWhat to do Part B Identifying sources of informationInformation about non-invasive and minimally invasive medical techniques can be found froma number of sources.Evaluate the quantity and quality of information that could be obtained on this topic from eachof the following areas.♠ The school library.♠ Encyclopaedias – World Book, Britannica♠ The local Public Library♠ Electronic sources – Encarta, etc♠ The Internet.Criteria to make a judgment includes quantity of information, readability (difficulty level,detail), reliability of source, how up to date is the information and others.© P Wilkinson 2002-04 11
  12. 12. Summative Questions42. Discuss the terms non-invasive and minimally invasive in relation to medical techniques.43. Describe the advantages of using minimally invasive surgery techniques such as key hole surgery44. Discuss the importance in diagnostic medicine of non-invasive diagnostic techniques including X-rays, ultrasound, thermography and magnetic resonance imaging (MRI).45. Discuss the advantages and disadvantages of minimally invasive medical techniquesNote the followingDiscuss questions require an extended answer.The question itself provides no structure for the answer.The steps below show one way of developing a structured answer (for question 43). Thisstructure could be used to for any discuss question. Step 1 Underline important words in the question non-invasive, minimally invasive, medical techniques. Step 2 Circle the KEY verb in the question and recall its meaning. Discuss – identify issues and provide points for/or against Step 3 Make a list of issues that could be used to answer the question. The question is asking you to consider what the two terms mean. Therefore, the issues relate to factors to consider in deciding if a technique is non-invasive or minimally invasive. Finally a definition or description of each type of technique is needed (with examples). Use the scaffold below to answer the question Issue 1 Penetrate the skin For - Against Issue 2 Amount of trauma, effect on normal functioning of the body Write appropriate definitions or descriptions© P Wilkinson 2002-04 12