Personal Dosimeters (6)

Question 1

Direct Reading Dosimeter (DRD)

Answer 1

• Read at any time
• Indication of exposure dose
• readings for x-ray or gamma

Ranges:
Low - 0-200mr, 0-500mr
Medium - 0-1000mr, 2R, 0-5R, 0-20R
High - 0-100R, 0-200R, 0-600R

Ionization chamber size of a pen, charged gives an electrostatic charge to quartz fibre and electrode (same charge and repel, stationary reads 0), when radiation enters it creates ion pairs, negative move towards electrode, reducing + charge and bending the fibre (movement = amount of ionization and intensity)

• must read minimum of twice a day
• record daily dose and submit
• cant be repaired

Question 2

Personal Alarming Dosimeter (PAD)

Answer 2

• Emits audible signal when pre-set dose/dose rate is reached

For electric:
some display dose rates in different units and measured accumulated dose, set up different alarm levels, store data

• calibrated yearly
• monitor dose rate and accumulated dose

Question 3

Thermoluminescent Dosimeter (TLD)

Answer 3

• Sent to dosimetry system every 2 weeks to be read
• Lifetime record
• accumulated dose to body and skin

two lithium fluoride chips (different thickness, shielded by metal foil), electrode from radiation get stuck in chips, chips are heated and amount of light (read by photomultiplier) = amount of accumulation

• chips can be reused

Question 4

Optically Stimulate Luminescence Dosimeter (OSL)

Answer 4

• Sent to dosimetry system every 2 weeks to be read
• lifetime record

thin layer aluminium oxide and filters in water resistant blister pack, radiation interacts with aluminium oxide, inducing stable effects, sample is illuminated, luminescence = amount of exposure.

• high sensitivity and precision
• can be reread
• replaced TLD
• x-ray, gamma, beta

Question 5

Ring Dosimeter

Answer 5

Worn on dominant hand, index, ring or middle finger

contains lithium fluoride chip, determined same as TLD (heated, light = radiation accumulated)

• plastic and velcro strap