A patient undergoing a prolonged fluoroscopic intervention develops a patch of erythema on the back. Which absorbed skin dose corresponds to the THRESHOLD for transient early erythema, a classic deterministic tissue reaction?
- A 0.2 Gy
- B 0.5 Gy
- C 2 Gy ✓
- D 10 Gy
Correct answer: C. 2 Gy
Explanation
Transient early erythema appears at a threshold absorbed dose of about 2 Gy, making it one of the earliest deterministic skin effects seen after prolonged fluoroscopy. Higher cumulative doses lead to main erythema, dermal necrosis and chronic ulceration at progressively larger thresholds. Deterministic effects require doses well above this level, show a clear threshold, and increase in severity with dose, unlike stochastic effects such as cancer induction.
Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.