Radiology 4. Biological Effects of Ionising Radiation & Risk Assessment Flashcards
what are the types of radiation (4 types)?
Alpha particle (2 protons/2 neutrons)
Beta particle (electron)
Gamma ray (electromagnetic radiation)
X-Rays
what happens to atoms when radiation passes through matter?
they are ionised along its path
how can radiation directly effect DNA?
radiation interacts with the atoms of a DNA molecule or another important part of the cell
how can radiation INDIRECTLY affect DNA?
Radiation interacts with water in the cell, producing free radicals which can cause damage
free radicals are unstable, highly reactive molecules
what happens to a single strand break in DNA when radiation affects it?
Single stranded breaks can usually be repaired
What happens to double stranded dna breaks when hit with radiation?
they are more difficult to repair than single stranded breaks. If the repair is faulty then this can lead to mutations which can affect cell function
what factors is the radiosensitivity of tissues dependent on? (2 factors)
the function of cells that make up the tissues
if the cells are actively dividing
what are the highest radiosensitive tissues?
bone barrow, lymphoid tissues, GI, gonads, embryonics
(the higher the cell division rate, the greater the sensitivity)
what is the least radiosensitive tissues?
CNS, Bone and Cartilage, connective tissue
what is the absorbed dose and its units?
Measures the energy deposited by radiation
Units - Grays (Gy)
what are the effects of radiation during pregnancy?
Radiation exposure could damage/kill enough of the cells for embryo to undergo resorption (kills itself)
Do precautions need to be taken for pregnant patients?
Pregnancy does not need to be taken into account for dental x-rays because the dose to the foetus is so low
the x-ray beam should not be directed towards the patient’s abdomen however.