The document discusses the general requirements and characteristics of dosimeters. A dosimeter is a device that measures radiation quantities like exposure, absorbed dose, and equivalent dose. It should be accurate, precise, and have a linear response over a wide dose range with little dependence on factors like energy, dose rate, or direction. Common types of personal dosimeters mentioned are film badges, pocket ion chambers, thermoluminescent dosimeters (TLD), optically stimulated luminescence (OSL) dosimeters, and solid state dosimeters. The document also discusses appropriate uses of personal dosimeters and factors to consider for different work environments.

2. General requirements for dosimeters
#Dosimeter is a device that measures directly
or indirectly
• Exposure
• Kerma
• Absorbed dose
• Equivalent dose
• Or other related quantities.
#The dosimeter along with its reader is
referred to as a
dosimetry system.

3. A useful dosimeter exhibits the following
properties:
• High accuracy and precision
• Linearity of signal with dose over a wide
range
• Small dose and dose rate dependence
• Flat Energy response
• Small directional dependence
• High spatial resolution
• Large dynamic range

4.  Accuracy specifies the proximity of the mean
value of a measurement to the true value.
 Precision specifies the degree of
reproducibility of a measurement.
Note:
High precision
is equivalent to small standard deviation.

5. Examples for use of precision and accuracy:
High precision High precision Low precision Low precision
and and and and
High accuracy Low accuracy High accuracy Low accuracy

6. Note: The accuracy and precision associated
with a measurement is often expressed in
terms of its uncertainty.

7. New Concept by the International Organization
for Standardization (ISO) "Guide to the
expression of uncertainty in measurement“
 This new guide serves as a clear procedure
for characterizing the quality of a
measurement.
 It is easily understood and generally
accepted.
 It defines uncertainty as a quantifiable
attribute.

8.  Standard uncertainty: is the uncertainty of a
result expressed as standard deviation.
 Type A standard uncertainty is evaluated by
statistical analysis of a series of observations.
 Type B standard uncertainty is evaluated by
means other than statistical analysis. This
classification is for convenience of discussion
only.
 It is not meant to indicate that there is a
difference in the nature of
 the uncertainty such as random or systematic.

9.  Combined uncertainties:
The determination of the final result is normally
based on several components.
Linearity:
 The dosimeter reading should be linearly
proportional to the dosimetric quantity.
 Beyond a certain range, usually a non-linearity sets
in.
 This effect depends on the type of dosimeter.

10. Two possible cases
Case A:
• linearity
• supralinearity
• saturation
Case B:
• linearity
• saturation

11. Dose rate dependence :
 M/D may be called the response of a dosimeter
system
 When an integrated response is measured, the
dosimetric quantity should be independent of the
dose rate dD/dt of the quantity.
 Other formulation:
The response M/D should be constant for different
dose rates (dD/dt)1 and (dD/dt)
2. M = 􀀁 (M / D)(dD / dt)dt
M = (M / D)􀀁 (dD / dt)dt

12.  Energy: The response of a dosimetric system
is
generally a function of the radiation energy.
 The term "radiation quality" is often used to
express a specific distribution of the energy
of radiation.
 Therefore, a dependence on energy can also
be called a dependence on radiation quality.
 Since calibration is done at a specified beam
quality, a reading should generally be
corrected if the user's beam quality is not
identical to the calibration beam quality.

13. A small radiation monitoring device worn by persons
entering environments that may contain radiation .
# Desirable characteristics
 Should be lightweight, durable, and reliable
 Should be inexpensive

14.  Healthcare or laboratory workers in non-
emergency environments that may contain
radiation
 Examples: radiology, nuclear medicine, and
radiation oncology department staff
 Workers in emergency environments that
may contain radiation
 Examples: first responders and first receivers
 Workers in industrial environments where
radiation is used
 Examples: nuclear power plant workers or
employees at radiation sterilizing facilities

15.  Flat badges are usually worn on the torso, at the
collar or chest level, but can be worn on the
belt, or forearm
 Ring shaped badges can be worn on the finger
when dose to the finger may exceed dose to the
badge worn elsewhere on the body
 First responders and first receivers
 Wear water-resistant personal dosimeters on the
outer layer of personal protective equipment (PPE).
 Should be able to easily see and hear a dosimeter
alarm while wearing PPE
 May wear a personal dosimeter underneath
waterproof outerwear

16.  Film badge
 Pocket ionization chambers
 Thermo luminescent dosimeters (TLD)
 Optically stimulated luminescence (OSL)
 Solid State

17.  Most widely used and most economical
 Consists of three parts:
 Plastic film holder
 Metal filters
 Film packet
 Can read x, gamma, and beta radiation
 Accurate from 10mrem - 500rem
 Developed and read by densitometer
 A certain density value equals a certain level of radiation
 Read with a control badge
 Results generally sent as a printout

18.  Lightweight, durable,
portable
 Cost efficient
 Permanent legal record
 Can differentiate between
scatter and primary beam
 Can discriminate between
x, gamma, and beta
radiation
 Can indicate direction from
where radiation came from
 Control badge can indicate
if exposed in transit
 Only records exposure
where it’s worn
 Not effective if not worn
 Can be affected by heat
and humidity
 Sensitivity is decreased
above and below 50 keV
 Exposure cannot be
determined on day of
exposure
 Accuracy limited to + or -
20%

19.  The most sensitive personnel dosimeter
 Two types
 Self-reading
 Non self-reading
 Can only be read once
 Detects gamma or x-radiation

20.  Small, compact,
easy to use
 Reasonably
accurate and
sensitive
 Provides
immediate reading
 Expensive
 Readings can be
lost
 Must be read each
day
 No permanent
record
 Susceptible to
false readout if
dropped or jarred

21.  Looks like a film badge
 Contains a lithium fluoride crystal
 Responds to radiation similarly to skin
 Measured by a TLD analyzer
 Crystal will luminescence if exposed to
radiation, then heated
 More accurate than a film badge

22.  Crystals contained
in TLD interact
with ionizing
radiation as tissue
does
 Determines dose
more accurately
 The initial cost is
greater than that
of a film badge
 Can only be read
once
 Records exposure
only where worn

23. • “Captures” information in an Aluminum
Oxide matrix
• Releases information by laser stimulation
• Can be reread after processing
• Durable
• Landauer Only

24.  Provides instantaneous information
regarding dose accumulation
 Simple to use
 Not a “legal” record
 Dose range device dependent