Whole Body Dosimeters (InLight Nova) - Technical Specifications

Dosimeter Overview

whole body dosemiter

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A front view of a single dosimeter that is rectangular in shape and royal blue in color that has an aperture at the top and bottom. Printed on a white label is Group: A12345 and the users name Paul B Smith printed below. The dosimeter serial number 483031 is printed at the very bottom of the white label with a 3D barcode to the left and another 3D barcode to the right. The wearing period start date 2016/01/01 and end date 2016/03/31 is printed in the top right corner and is hightlighted in a yellow textbox. The Health Canada logo appears in the bottom right corner of the white label and just below this is the acronym NDS-SND. The top left side of the label has a red rectangular textbox with InLight centred above a character that has a black square box placed over the heart area.

InLight Nova dosimeters provide X-ray, gamma and beta radiation monitoring using optically stimulated luminescence (OSL) technology. Each InLight Nova dosimeter is shipped to the client fully assembled in a dosimeter holder labelled with the wearer's name, the wearing period start and end dates, group number, wearing location and a dosimeter serial number.

OSL is a passive dosimetry technology. A passive dosimeter contains sensitive elements that absorb and store energy as the wearer is exposed to ionizing radiation. When the dosimeter is processed, the stored energy is released as light, which is measured. The reported radiation dose is proportional to the amount of light that is measured.

The InLight Nova dosimeter contains four OSL elements, each made of crystalline aluminum oxide doped with carbon (Al2O3:C) that has been crushed into powder and sandwiched between two thin plastic sheets. Each OSL element is positioned between a pair of filters made of a different material (thin mylar plastic, thick plastic, aluminum, and copper). These filters provide a different degree of screening to each element, so that ratios of element readings can be used to identify what kind of radiation the dosimeter has been exposed to.

Dosimeter Reading Equipment

InLight Nova dosimeters are processed using automated readers. During readout, each OSL element is stimulated using a strong beam of LED light to luminesce (or release stored energy as light). A wavelength filter is used
to separate the stimulation light from the released light, and a photomultiplier tube is used to record the luminescence signal.

dosemiter reader

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One InLight Auto 200 Reader System. The OSL dosimeter reading system has two lower compartments and an open laptop placed on top of the right compartment. The laptop's screen is displaying a dose measurement software program. The compartment on the left has three round operating lights at the top left corner that are green, yellow and red. The compartment on the right is slightly open and shows a partial view of one dosimeter magazine and three empty reader racks.

Dose Analysis Process

National Dosimetry Services technologists carefully review the signals recorded from each InLight Nova dosimeter to ensure accuracy. A dose calculation algorithm is then applied to the signals. The algorithm uses ratios of element readings to characterize the energy of the incident radiation, and then uses this information to select conversion factors that can be applied to the readings to determine radiation doses. This process ensures accurate dosimeter readings over a very wide range of radiation energies.

Next, the doses are converted to occupational doses by subtracting contributions from environmental background radiation. These contributions are determined using control dosimeters and other sources of information about background radiation levels at client work sites. Finally, the occupational doses are reported to the National Dose Registry and an Exposure Report is mailed to the client.

chart

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The image shows line graphs representing the data readings extracted from the four Optically Stimulated Luminescence (OSL) elements found on the dosimeter. The X axis measures 20 data points for each element and the Y axis represents the raw counts. The different element colors are identified in the following table.

Elem 1 – Green Font
This element is an open window, there is no filter present
Elem 2 – Red Font
This element has a Plastic filter
Elem 3 – Yellow Font
This element has an Aluminum filter
Elem 4 – Blue Font
This element has a Copper filter

Accreditations

Technical Specifications

Dosimeter Name:
InLight Nova OSL Dosimeter
Dosimeter Type:
Passive
Radiation Detected:
X-ray, Gamma and Beta
Wearing Location:
Whole Body
Doses Reported:
Hp(10), mSv ("Deep Dose" or "Body Dose") Hp(0.07), mSv ("Shallow Dose" or "Skin Dose")
Energy Response:
Photon (X-ray and Gamma):
20 keV to in excess of 6000 keV Beta (Max): 687 keV to in excess of 2274 keV
Reporting Threshold:
0.10 mSv
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