Deterministic Radiation Effects
Overview
Deterministic effects (also known as non-stochastic effects) are radiation-induced tissue damage that occur above a threshold dose and increase in severity with increasing dose.
Mechanism
- High doses of ionizing radiation above threshold cause direct cell death
- These effects have a dose threshold below which they do not occur
- Severity of the effect increases with dose above the threshold
Acute Reactions
Immediate/Early Effects
- Erythema - Skin redness and inflammation
- Acute radiation syndrome - Systemic response to high-dose radiation exposure
Characteristics
- Predictable occurrence above threshold dose
- Dose-dependent severity
- Threshold dose varies by tissue type and individual sensitivity
Clinical Examples
| Tissue/Organ | Threshold Dose | Deterministic Effect |
|---|---|---|
| Skin | ~2 Gy | Erythema, desquamation |
| Lens of eye | ~0.5 Gy | Cataract formation |
| Bone marrow | ~0.5 Gy | Hematopoietic syndrome |
| GI tract | ~6 Gy | GI syndrome |
| Gonads | ~0.1 Gy | Sterility |
Radiation Protection Implications
- Dose limits are set well below deterministic effect thresholds
- Monitoring ensures cumulative doses stay below threshold levels
- Shielding techniques minimize deterministic risk
- Justification of procedures weighs benefits against deterministic risks