Radiation Carcinogenesis Flashcards
Non-Stochastic (Deterministic) Effects
Have a threshold and above the threshold the severity increases with dose
Stochastic Effects
No threshold, severity is unrelated to dose, and probability of occurrence increases with dose
Latent Period
The time between irradiation and appearance of disease
Latent period for Leukemia
5 - 15 years
Latent period for solid cancers
10 - 60 years
Types of risk models
Absolute Risk Model
Relative Risk Model
Time-dependent Relative Risk
Absolute Risk Model
Radiation induces cancers at some fixed number above the natural incidence
Relative Risk Model
Radiation increases the natural incidence at all ages proportional to spontaneous background rates
Time-dependent Relative Risk Model
Function of dose, age at exposure, time since exposure, gender, etc.
Leukemia
Acute and chronic myeloid - more prevalent in irradiated adults
Acute lymphatic or stem cell - more susceptible in childhood
Highest relative risk of any malignancy
Dose response fits a linear quadratic (risk at 1 Sv is 3x risk at 0.1 sv)
Thyroid Cancer
High sensitivity for radiation carcinogenesis
Children particularly susceptible
Slow to develop
Surgical removal or radiation ablation is very successful
Low mortality rate of 5%
Breast Cancer
Large difference in natural background vs. irradiated groups
Typically occurs in duct cell region but can occur in breast tissue
Data tend to support a linear relationship between occurrence and dose
Lung Cancer
Radiation is one of many carcinogens associated with lung cancer
Bone Cancer
Long 1/2 life materials settle in bone volume while shorter 1/2 life materials effect bone surface
Hemotopoietic stem cells and Osteogenic/epithelial cells are the target
Skin Cancer
Modern safety standards have virtually eliminated this hazard of radiation workers
Highly treatable
