← Radiation Protection / Sim: T·D·S Calculator

Time · Distance · Shielding Calculator

Quantify how each lever changes operator dose. Reference scatter rate at 1 m from a typical fluoroscopy patient is ~1 mSv/hour per 100 mGy/min of patient entrance dose (scatter is ~0.1% of entrance).

Fluoro time (min) 20 Patient entrance rate (mGy/min) 40 Operator distance (m) 1.0 Apron Pb equivalent (mm) 0.35 Ceiling shield use (%) 0

Scatter @ 1 m

—

mSv/h

At operator

—

mSv/h

Behind apron

—

mSv/h

Case total

—

mSv (effective)

Teaching notes

Scatter dose rate at 1 m is approximately 0.1% of the patient entrance dose rate. The apron attenuates by a factor that depends on beam energy; 0.35 mm Pb ≈ 10× attenuation for a 100 kVp beam. Ceiling-mounted drapes add ~3–5× attenuation when positioned well. Total operator dose = scatter rate × time × (distance factor) × (apron factor) × (ceiling factor). You'll notice that time and distance are the most dramatic knobs at the bedside.