Sources of Radiation & its Biological Effects

1. Sources of Radiation & its
Biological Effects

25. RADIATION EFFECTS ON CELLS
Basically, there are three things that can happen:
1. The radiation may pass through the cell without doing any damage to
cell.
2. The radiation may damage the cell so that the cell not only form to
repair itself but reproduces itself in the damaged form – Biological
Response.
3. The radiation may cause so much damage, cells dies

26. EFFECTS OF LOW DOSE RADIATION
Low-Dose Radiation The low dose or “stochastic” effects (statistical),
which could be seen are:
Carcinogenesis (i.e. induction of cancer) and
Genetic effects (i.e. damage seen in offspring)

27. DETERMINISTIC EFFECTS
• They are dose related, The injury increases in severity as dose
increases.
• They are generally not an issue in diagnostic imaging – the doses are
too low.
• They are predictable
• Mechanisms are relatively well understood e.g., in radiotherapy
• Repair and recovery can occur.

28. OTHER TOXIC DOSE EFFECTS
• Hair Loss
• Sterility
• Cataracts
• Skin Burns

29. SENSITIVITY
• In a malignant tumors the cell system will be much sensitive.
• Outer layer of cells reproduce rapidly and has a good supply of blood
and oxygen
• The cells become more sensitive when they are reproducing, and the
presence of oxygen increases sensitivity to radiation.
• In anoxic cells it tend to be less reactive .

30. • As the tumor is exposed to the radiation ,outer layer of rapidly
dividing cells are destroyed, ceasing it to the shrunken image.
• In tumor if massive dose is given the patient may die hence small dose
is given each day which gives a healthy tissue ,a chance to recover
from damage.

31. WHOLE BODY SENSITIVITY FACTORS
• Total dose
• Type of cell
• Type of radiation
• Stage of cell division
• Part of body exposed
• General state of health
• Tissue volume exposed
• Time interval over which dose is received