module 12 chapter 14-- radiation monitoring

what is the NRCP’s annual EfD limit for radiation workers?

50 mSv

monitoring radiation exposure of anyone who is regularly occupationally exposed is:

recommended.

monitoring radiation exposure of any worker who is likely to receive 10% or more of the annual occupational limit of 50 mSV annually because of their occupational activities is:

required

most health care facilities issue dosimeters when personnel may receive _% of the annual occupational EfD limit in any month

1%

why do radiation workers wear personnel monitoring devices?

provides an indication of habits and working conditions and detecting and measuring exposure

why should a dosimeter be worn on clothing on the front of the body?

approximates maximum

consistency ___ in wearing the dosimeter is necessary

location

dose that is within acceptable range outside the apron will insure ___ readings under the apron

minimal

where do pregnant RTs wear their baby dosimeter?

wear under apron at waist level

where is an extremity dosimeter worn?

on finger as a ring

why would someone wear an extremity dosimeter?

when hands will be exposed on a regular basis. common in nuclear medicine, IR, and CI

characteristics of personnel dosimeters are:

they are lightweight and easy to carry, durable to withstand normal daily use, able to detect small and large exposures consistently, kept away from ____, inexpensive to purchase and maintain

heat and humidity

what are the types of dosimeters?

optically stimulated luminescence dosimeters (OSL), thermoluminescent dosimeter (TLD), pocket ionization chamber, electronic personal dosimeter (EPD)

what is the most common type of dosimeter used for monitoring of occupational exposure in diagnostic imaging?

optically stimulated luminescence dosimeter (OSL)

what is the OSL dosimeter made of?

aluminum oxide

when the ___ interacts with the sensing material it becomes luminescent in proportion to the amount of radiation exposure received

laser

in an OSL dosimeter, amount of light equals:

amount of radiation exposure

different types of filters (aluminum, tin, copper) ___ radiation before striking the badge providing radiation penetrating power levels

attenuate

the OSL dosimeter is sensitive to ___ for x-ray and gamma ray photons with energies ranging from __ to __

10 μSv; 5 KeV to 40 MeV

what is the sensitivity in an OSL personnel dosimeter ideal for?

monitoring employees working in low-radiation environments, for pregnant workers

energy levels recorded correlate with penetrating ability and are usually stated as:

deep, eye, shallow

what are positives of the OSL dosimeter?

lightweight, durable, easy to carry, heat, moisture and pressure will not affect the reading, can record low and high exposure readings, can be used for up to year before reading

what are the negatives of OSL dosimeter?

must send away so can’t get same day or immediate reading

where is a thermoluminescent dosimeter mainly used?

in extremities

what is the sensing material in a TLD?

lithium fluoride

ionizing radiation causes the LiF to undergo a:

physical change

in a TLD, electrons are energized and captured in the ____ of the LiF

crystalline lattice

when the crystalline lattice of theLiF is heated (thermos), the electrons can discard their excess energy int he form of:

visible light (luminescence)

in the TLD, intensity of the light is is ___ to the amount of radiation that interacted with the crystals

proportional

what does a TLD analyzer do?

heats the crystals and measures the light given off by the electrons; “glow curve”

LiF interacts with ionizing radiation similar to:

human tissue, can measure very low amounts of exposure accurately

do humidity, pressure and normal temperature change affect the TLD?

no

how long can TLDs be worn without fogging?

3 months

what are some perks to TLDs?

can be reused once read, more sensitive than OSL

what are negatives to TLDs?

can be read only once and the information is then destroyed, dosimeters must be calibrated before each use, no immediate results

what is the most sensitive type of personnel dosimeter?

pocket ionization chamber

what are some characteristics of a pocket ionization chamber?

has thimble size ionization that measures radiation exposure, quartz reacts and moves according to the charge measured from the ionization chamber, can see immediate measurement

wha are some positives to pocket ionization chamber?

immediate exposure readout (good for workers working in high exposure area, can alter working habits immediately if needed). compact, easy to carry, convenient

what are negatives to pocket ionization chamber dosimeter?

expensive, needs to be charged daily, can give inaccurate reading as charge tends to escape, charge can escape due to mechanical shock (being dropped) leaves no physical permanent legal record of exposure

what is an electronic personal dosimeter?

similar to the pocket ionization chamber, but has a real-time digital display and is more accurate and stable

what are some characteristics of an electronic personal dosimeter?

can store exposure data with time stamps and exposure history, audible/visual alarms for high dose or dose rate

what dosimeter is common for routine monitoring?

OSL

what dosimeter is best for accuracy and reusability?

TLD and OSL

what dosimeter is best for real-time exposure awareness?

digital dosimeter (EPD)

what dosimeter is mostly outdated with limited use?

pocket ionization chamber

which dosimeter offers instant reading and alarms and stored data?

digital dosimeter (EPD)

which dosimeter has immediate reading with no stored record?

pocket ionization chamber

which dosimeter is the most common and keeps a personal record?

OSL

which dosimeter is reusable and accurate, keeps permanent record?

TLD

what is the geiger-muller detector for?

portable radiation survey instrument for area monitoring in nuclear medicine facilities

the geiger muller detector is sensitive enough to detect:

individual particles (electrons) or photons

what are characteristics of a geiger-muller detector?

can be used to check any area contaminated by radioactive material, can be used to locate radioactive source or low-level radioactive contamination

a geiger-muller detector has a ___, weak radioisotope located on one side of its surface used for daily calibration

long half-life

readings obtained as ___ per hour

microSieverts (μSv/hr)

disadvantages of geiger-muller detector

readings are not independent of the energy of the incident photons, can saturate or jam when placed in a very high intensity radiation area, and give a false reading

photons of widely different energies cause the instrument to respond:

differently (disadvantage in diagnostic imaging where photons vary in degree of energy)

ionization chamber type survey meter

Cutie Pie

Cutie Pie characteristics

can measure exposure rate and cumulative exposure, measures x-radiation and gamma radiation and can be adapted to measure beta radiation

the Cutie Pie can measure exposure rates of .09

.09 μSv

the cutie pie device can monitor x-ray installations when exposure times of over __ are used

1 second

Cutie Pie measures ___ radiation exposure rates

fluoroscopic scatter

Cutie Pie measures exposure rates of patients with ___ doses of radioactive materials

therapeutic doses; brachytherapy— internal radiation implants

Cutie Pie can be used to measure ___ received outside protective barriers

cumulative exposures

what is an advantage of using Cutie Pie?

can measure a wide range of radiation exposures within a few seconds

what are disadvantages of using Cutie Pie?

needs a warm-up time, cannot be used to measure dose of general radiology procedures because exposure times are too short for a measurement

the Cutie Pie ionization chamber is:

filled with gas, radiation ionizes gas, electrical signal from freed electrons is measured

why measure your own exposure?

protects your health, ensures regulatory compliance (confirms you are staying within dose limits set by organizations like the NRC), promotes safe work practices, provides legal record of exposure, identifies equipment or procedural issues, supports ALARA