Chapter 5 Radiation monitoring Powerpoints

Personnel dosimetry
~ exposure monitoring of personnel is required whenever
radiation workers are likely to receive _____ of the
annual occupational effective dose limit of 50 mSv in any single
year

10% or more

Personnel dosimeter
~ provides an indication of the working habits and conditions of
diagnostic imaging personnel
~ it determines _____ exposure by detecting and
measuring the quantity of ionizing radiation to which the
dosimeter has been exposed over a period of time
~ this instrument does not protect the wearer from exposure

occupational

~the _____ records only the exposure
received in the area where it is worn

personnel monitoring device

~ during routine rad. procedures, when protective apron is not
being used, the primary personnel dosimeter should be
attached to the clothing on the front of the body at collar level
~ this level allows the most accurate reading for the _______
~ consistency of location in wearing the dosimeter is the
responsibility of the radiographer

thyroid, head, and neck

_____ procedures produce the
highest occupational radiation exposure for dx imaging
personnel

Fluoroscopy and special radiographic

~ when the technologist is wearing a protective apron, the
dosimeter should be worn outside the apron at collar level on
the ____surface of the body

anterior

~ when the dosimeter is worn at collar level, it provides a
reading of the _____ to the thyroid gland and eyes of the occupationally exposed person

approximate equivalent dose

~ the secondary monitor is worn beneath a wraparound-style
lead apron at _____ to monitor equivalent dose to the lower
body trunk

waist level

Monitor for the embryo-fetus
~ a second monitoring device is worn to record the radiation
dose to the ____during gestation

abdomen

_______ or _______
~ is worn by an imaging professional as a second monitor when
performing radiographic procedures that require the hands to
be near the primary beam (Nuclear Medicine Technologists)

Extremity dosimeter, TLD ring badge

~ monitor measures the approximate equivalent dose to the
hands of the person wearing the ring

TLD ring badge

TLD ring badge over contains the following information:
1. account number
2. tech. name and number
3. wear date
4. indication of hand its worn
5. size
6. reference #
This information is _____ to ensure permanent id.

laser-etched

TLD ring badge:

~ the laser etching allows for the ring to be worn during scrub
procedures without damaging the identification
~ the reusable TLD element of the dosimeter is _____
within the engraved cover

encapsulated

There are two types of personnel dosimeters used to measure
individual exposure of the body to ionizing radiation:

1. optically stimulated luminescent (OSL) dosimeters
2. Direct ion storage (DIS) dosimeter

~ contains aluminum oxide detector
~ dosimeter is struck by laser light at selected frequencies, there
is a luminescent in proportion to the amount of radiation
exposure received

OSL

~can be worn up to one year, usually worn only 2 months at a
time
~ occupational exposure can not be determined on the day of
occurrence

Optically stimulated luminescence (OSL) dosimeter

Energy discrimination is provided by three different filters
incorporated into the detector packet
~filters are made of _____

aluminum, tin, and copper

~each filter blocks a portion of the radiation sensitive aluminum
oxide OSL, causing a different degree of _____ for any
radiation striking the badge depending on its energy

attenuation

~ the Al filter offers the least absorption and the ____filter
attenuates the most

copper

when ____ radiation strikes, the badge would show a
similar reading throughout all of the filters

high energy

if only low energy radiation strikes the badge, the laser read
out would be much more pronounced in the region covered by
_____

aluminum

The OSL dosimeter provides a more accurate reading as low as
1mrem from energies ranging from _____

5keV to 40MeV

~ should be kept in a radiation-free area within the imaging facility
~ optical density should be “0”
~ if after processing the reading is above “0”, the batch of badges
may have been exposed to radiation while in transit
~a reading higher than “0” must be subtracted from the total badge
reading

OSL Control monitor

Advantages of OSL:
• Lightweight, durable, and easily worn
• Has a tamperproof blister packet that is not effected by______

heat, moisture, and pressure

Disadvantages of OSL:
• Exposure is recorded only in the area worn
• If the facility does not have an in ____, exposure cannot
be determined on the day of occurrence

house reader

Information found on a personnel monitoring report:
1. personal data – identification number, name, DOB, and sex
2. type of dosimeter – “_” represents an OSL; “_” represents
finger badge
3. radiation quality
4. equivalent dose data ( deep, eye, shallow recorded dose
equivalents for a time indicated on the report)

p, u

Information found on a personnel monitoring report:

5. ______ for deep, eye, and shallow
radiation for calendar quarter, year to date, and lifetime
6. inception date that the monitoring company began keeping
records for the individual listed on the account who is wearing
an monitoring device

cumulative equivalent doses

When employment changes, the Rad Tech must convey the data
pertinent to accumulated permanent equivalent dose to the _____ ( a copy of last occupational exposure report)

new employer

A small ionization gas filled dosimeter connected to a “solid
state” device, with electrically erasable programmable read-only
memory (EEPROM, or E2PROMs).

Direct Ion Storage (DIS) Dosimeter

are used in microcomputers and various consumer
products to store small amounts of data while allowing some
memory to be erased and reprogrammed to store more data.

EEPROMs

In the personnel dosimeter, when radiation ionizes the gas in
the ionization chamber, the cumulative electric charge is stored
in the EEPROM and will remain in the device indefinitely, until
either added to by additional ionization or until “_____” by the
introduction of a small control signal.

read out

The amount of charge stored in the device is ______ to the amount of radiation exposure produced ionization that has occurred in the chamber

directly proportional

The DIS dosimeter is read out through a physical connecting device such as a universal serial bus (USB) or via wireless connection, and the data can then be stored _______. However, it may also be read out by the device wearer via a cellphone application. Thus, the individual wearer may obtain an instantaneous readout while the facility is able to obtain their own reports, such as:
• Radiation exposure summary
• Exposure history
• Individuals who have not had their devices read

electronically at the facility

Advantages of the direct ion storage dosimeter:
• instant access to data and no need for the
___to collect individual dosimeters, mail
them to the manufacturer for readout, and issue
new dosimeters to the individuals.
• DIS dosimeters are lightweight, durable, and
can be dropped or scratched with little chance
of harm to the device.

institution

Disadvantages of the DIS:
• Radiation exposure cannot be determined if _____

the dosimeter is not regularly used.

Radiation survey instruments fall into three categories:

those without a readout scale, those with a readout scale, and those that have a readout scale and are ionization-chamber based.

Radiation detection and measurements:
~radiation survey instruments
      - area monitoring devices that detect and measure radiation
      - indicates the presence or absence of radiation
~ when the ionizing radiation is contact with the survey instruments, they respond to the charged particles that are produced b/c radiation interacts with and ionizes the ___ in the detector

gas

Types of radiation survey instruments:

1. cutie pie
2. proportional counter

3. Geiger-Muller service meter

( most common)
~ all 3 are gas filled radiation detectors
~ they detect presence of radiation

Geiger-Muller service meter

ionization chamber-type survey meter

cutie pie

Requirements of radiation survey instrument for area monitoring:
1. easy to carry so they can be used by one person over a period of time
2. durable to withstand normal use
3 reliable to accurately assess radiation exposure or exp. Rate
4. should interact with ionizing radiation the way human tissue does
5. detect all common types of ionizing radiation
6. energy of radiation should not affect the response of the
detector and the direction of the incident radiation should not
affect the performance of the unit
7. _________
8. Calibrated annually to ensure accurate operation

cost effective

~ rate meter for area surveys and accurate cumulative
exposure instrument

Ionization chamber-type survey meter (Cutie pie)

(Cutie Pie) Usage:
1. to monitor diagnostic x-ray installments and measure
fluoroscopic and computed tomography scatter radiation
2. exposure rates of patient containing ______ of
radioactive materials
3. exposure rates in radioisotope storage facilities
4.cumulative exposures received outside protective barriers

therapeutic doses

~ able to measure wide range or radiation exposure within a
few sec

Ionization chamber-type survey meter (Cutie pie) Advantages

1. delicate detector 2. warm up time

Ionization chamber-type survey meter (Cutie pie)Disadvantages

~ no useful purpose in diagnostic imaging

Proportional Counter

~ primary radiation survey instrument for area monitoring in
nuclear medicine
~ unit is sensitive enough to detect individual particles, so it can
detect any area contaminated by radioactive material
~ can be used to locate lost radioactive source or low level
radioactive contamination
~ has audible sound system that alerts the operator to the
presence of ionizing radiation
~ measured in mR/hr
~ can detect very low energy x-ray and beta/gamma radiation

Geiger-Muller (GM) Detector

photons of widely different energies cause the
instrument to respond differently and it is likely to jam when
placed in a very high intensity radiation area

Disadvantages Geiger-Muller (GM) Detector