5. Electromagnetics and the body Flashcards
(19 cards)
What are EM waves?
Disturbances in electric and magnetic fields caused by accelerating charges.
What does a higher frequency wave mean?
More energy (e=hf)
What does the dual nature of EM radiation mean?
EM radiation can behave waves and particles (photons )
What is ionizing radiation?
- Has enough energy to remove electrons from atoms
- Em energy > eV
What EM waves are ionising?
gamma, x-ray, some UV
Risks of ionising radiation. What medical imaging technique is it used in?
DNa damage and cancer. CT
What is non-ionising radiation? Which Em waves?
Cannot ionize atoms but excites them (causes movement/vibration) Radio, microwaves
What is non-ionizing radiation used in?
MRI, wearable devices.
Effects of ionizing radiation.
damage DNA, kill, or cause mutilations; lead to cancer.
What is the absorbed dose.
Concentration of energy of ionising radiation that is deposited in living matter.
What is the equivalent dose?
Accounts for the relative biological effects of different types of radiation.
What does effective dose account for?
Sensitivity of tissue.
What is radiotherapy?
Uses ionising radiation to kill or control cancer cells.
What are 2 techniques to minimise harm in radiotherapy?
- Dose fractionation: divide dose into small parts over days; targets diving cancer cells. allows healthy cells to recover.
- Focused dose: limits exposure to healthy tissue.
2 types of focused dose?
- External beam—precisely aimed x-rays
- Brachytherapy—implanted radioactive material.
wavelength of radiofrequency
1 mm-100 km (low frequency EM waves)
What is the radiofrequency interaction with the body?
through absorption leading to tissue heating. High levels can cause tissue damage through burning.
What does specific absorption rate measure (SAR)?
Measure how much RF energy is absorbed by the body. Changes by body part.
3 medical applications of RF?
1.MRI
2. RF ablation: heat destroys cancers
3. Implants and wearables, used to commuicate with devices in body.
