Chapter 6: Introduction to Medical Physics – Physics Form Six

INTRODUCTION TO MEDICAL PHYSICS

1.0 INTRODUCTION

Medical physics is a branch of physics that applies the principles, methods and techniques of physics to medicine and healthcare.

It combines knowledge from:

1. Physics
2. Biology
3. Medicine
4. Mathematics
5. Engineering
6. Computer science

Medical physics plays an important role in the diagnosis, treatment and monitoring of diseases.

Major areas of medical physics include:

1. Diagnostic imaging
2. Radiation therapy
3. Nuclear medicine
4. Radiation protection
5. Medical instrumentation
6. Health physics
7. Dosimetry
8. Physiological measurements

PART A: CONCEPT OF MEDICAL PHYSICS

2.0 CONCEPT OF MEDICAL PHYSICS

2.1 Definition of Medical Physics

Medical physics is the application of physics principles and techniques to the prevention, diagnosis and treatment of disease, as well as to the development and safe use of medical technologies.

A medical physicist is a professional who applies physics knowledge to areas such as:

1. Medical imaging
2. Radiation therapy
3. Radiation protection
4. Nuclear medicine
5. Dosimetry
6. Quality assurance of medical equipment

2.2 Importance of Medical Physics

Medical physics is important because it helps healthcare professionals to:

1. Produce medical images.
2. Diagnose diseases.
3. Treat cancer using radiation.
4. Measure radiation doses.
5. Protect patients and healthcare workers from unnecessary radiation.
6. Ensure medical equipment operates correctly.
7. Improve the quality of medical procedures.
8. Develop new medical technologies.

KEY EXAM POINTS

Medical Physics

Remember:

1. Medical physics applies physics to healthcare.
2. Medical physicists work in imaging, radiation therapy, nuclear medicine and radiation protection.
3. Medical physics improves safety, accuracy and quality in medical procedures.

Radiation Physics

Remember:

1. Radiation can be ionizing or non-ionizing.
2. X-rays and gamma rays are electromagnetic ionizing radiation.
3. Alpha and beta radiation are particle radiation.
4. Photon energy is E = hf.
5. Shorter wavelength means higher photon energy.

Radiation Protection

Remember:

1. Justification means the procedure should have a valid benefit.
2. Optimization means keeping exposure appropriately low while achieving the required clinical purpose.
3. Time, distance and shielding are fundamental protection methods.
4. Absorbed dose is measured in gray.
5. Equivalent and effective doses are measured in sievert.
6. Personal dosimeters monitor occupational exposure.

Medical Imaging

Remember:

1. X-ray uses ionizing radiation.
2. CT uses X-rays and computer reconstruction.
3. MRI uses magnetic fields and radiofrequency waves.
4. Ultrasound uses high-frequency sound waves.
5. Nuclear medicine uses radiopharmaceuticals.
6. PET and SPECT provide functional information.

Radiation Therapy

Remember:

1. Radiation therapy is used mainly to treat cancer.
2. Ionizing radiation can damage cellular DNA.
3. External beam therapy uses radiation from outside the body.
4. Brachytherapy places a radioactive source near or inside the treatment area.
5. Fractionation divides the treatment dose into multiple sessions.
6. Treatment planning aims to maximize tumour control while minimizing unnecessary dose to healthy tissues.

Ethics

Remember:

1. Beneficence means doing good.
2. Non-maleficence means avoiding harm.
3. Autonomy means respecting patient decisions.
4. Justice means fairness.
5. Confidentiality protects patient information.
6. Integrity requires truthful reporting.
7. Accountability requires responsibility for professional actions.

Chapter 6: Introduction to Medical Physics – Physics Form Six

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