UNITS OF DOSE
PERSONAL MONITORS
ROOMS & SIGNS
HOT LAB RULES
DO THE MATH
100
What is the roentgen (R)?
This traditional unit measures ionization of air by photons only, not energy deposited in tissue.
100
What is an OSL dosimeter?
This badge stores dose in aluminum oxide and gives up the signal when a laser hits the chip.
100
What is an unrestricted area?
The public may enter this area freely; dose must stay at or below 2 mrem in any one hour.
100
What is daily (on days of use)?
Do an ambient Geiger survey this often in rooms where radiopharmaceuticals are prepared or given.
100
What is the square? (inverse square law)
From a point source, intensity falls with the inverse of this function of distance.
200
What is the gray (Gy)?
This SI unit of absorbed dose equals 1 joule per kilogram, or 100 rad.
200
What is a film badge?
Heat, humidity, and water easily ruin this oldest whole-body monitor, and it has a short shelf life.
200
What is a controlled area?
Access is limited for radiation protection; visitors come in only under staff supervision.
200
What is weekly?
Do wipe tests of radioactive waste storage on this schedule.
200
What is one-fourth?
Double your distance from a point source and intensity drops to this fraction.
300
What are 1 rad and 1 rem?
For diagnostic x-rays and gamma rays in soft tissue, 1 R is treated as about equal to these two traditional units.
300
What are a pocket ion chamber and an electronic personal dosimeter?
This pair of devices can show dose in real time but is too inaccurate to be the legal dose of record.
300
What is Caution - Radiation Area?
Post this sign where a person could receive more than 5 mrem in one hour at 30 cm.
300
What is 1 meter?
The Transport Index on a package is the mrem per hour reading at this distance.
300
What is 3.6 mm?
Aluminum at 100 kV has mu = 0.1925 mm^-1. HVL = 0.693 / mu, so the HVL is this.
400
What is the quality factor (Q)? (also called wR)
This factor converts absorbed dose into dose equivalent so an alpha particle counts more than an x-ray.
400
What is the collar, outside the apron?
When a lead apron is on, the whole-body occupational badge belongs in this spot.
400
What is 2 mrem?
NRC calls a space restricted if someone could receive more than this in any one hour.
400
What is 0.5 mrem/hr?
A White-I package may not exceed this surface reading.
400
What is 1.67 mR/hr?
A reading of 15 mR/hr at 2 feet becomes this at 6 feet.
500
What is effective dose?
This quantity multiplies each organ equivalent dose by a tissue weighting factor, then adds them up.
500
What is 10%?
A worker should be assigned a badge if they are likely to exceed this fraction of the annual occupational limit.
500
What is Caution - High Radiation Area?
Post this sign where a person could receive more than 100 mrem in one hour at 30 cm.
500
What is 500 mrem?
After a written declaration of pregnancy, this is the dose limit to the embryo/fetus for the rest of gestation.
500
What is 3.30 mm?
Five mm of a new shield leaves 35% of the original exposure rate. The material HVL is this.
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