The
TASLIMAGE System
Introduction
We
produce a fully automated image analysis (reader)
system for scanning and analysing TASTRAK etched track detectors, and for
measuring etched particle tracks. The
system is designed
both for:
·
Routine analysis of radon dosemeters.
·
Routine neutron dosimetry.
·
Research applications of the analysis of etched track detectors
The system is pictured here.
We have been producing fully
automated etched track image analysis (readout) systems for around 20 years.
We operated a UK validated radon
measurement service for 10 years. This
was based on conventional etching of TASTRAK CR-39 with a custom designed
plastic holder. All of our reader systems
are based on conventional
transmitted light microscopy, which offers substantial advantages over less
detailed methods of data acquisition.
This
sophistication in the processing is completely hidden
from the operator who just sees the dosemeters being
processed and can process a complete tray of detectors
without requiring manual intervention. In addition
to this, the image processing allows the background
on the detectors to be determined separately from the
track signal, resulting in very low backgrounds. This
has the consequence that methanol (background deleting)
pre-etches are not required, even for fast neutron dosimetry.
The unique feature of the system
is our TASLIMAGE software, which is our own creation.
The software scans the plastic at a higher magnification than a number of
other etched track readers, providing a better quality of track image for
processing and better discrimination between tracks and background features.
Each feature located in the image is analysed separately by the program,
which makes 15 characteristic measurements to provide reliable discrimination
between etched tracks and background features present on or in the plastic
detectors. These measurements
include track length and diameter, optical density (average image contrast) and
image symmetry. The images are
acquired at a rate of 8 full image frames per second, and the acquired images can
be
“stitched” together in an optimal manner to ensure that the full scan area
is covered in the shortest possible time. For
radon dosimetry, it is possible to discriminate between tracks of 214Po
and 218Po, if required.
Our System Specification
One of the special features of this system is that
the readout is made using a high quality microscope
optical system (we use the Nikon cfi series) at a magnification
high enough to discriminate between tracks and background,
making this system accurate and reliable. The
computer system is fast, so analysis can be made at
high speed.
The
elements of the system are:
(a)
Pentium 4 computer of 2.8GHz or faster, with motherboard
and chipset compatible with frame grabber.
(b)
Computer programmable camera.
(c)
Frame grabber.
(d)
Microscope with high quality Nikon optics and ultra-fast
3 axis motorised control. The microscope has a stage
of area of 152x152mm or 203x203mm, depending on required
throughput.
(e)
"TASLimage" software to scan detectors fully
automatically.
The key features of TASL image are:
*
Fully automatic scanning of barcodes and etched tracks.
*
Fully automatic autofocus by software.
*
Etched track measurement by sophisticated image analysis
algorithms discriminating between etched tracks
and background features using 15 measured properties
of each located object.
*
Automatic background assessment of each detector.
*
A complete detector readout takes between 30 and 60
seconds depending on user selectable options.
*
The measurements and track counts are available for
external analysis.
*
The software saves all the measurements of all the tracks
it accepts, and saves a summary result in an archive
file.
*
The scan data is automatically converted to dose, and
the results are displaying immediately in the record
keeping database provided as part of the "TASLimage"
software. The data can also be exported to other programs
such as Excel.
Our system uses a completely software based autofocus
method. Focussing is achieved by periodically
focussing on the track images, or by focusing on a fiducial
box engraved round the edge of the detector.
The system uses our own format of bar code, which
can be quickly read by the microscope imaging system.
It can also scan plastics without barcodes, if
required.
A typical configuration is:
Stainless steel etch/scan holders are provided
are are shown here. These
are designed to hold the plastics for etching, drying
and scanning without the need to remount the plastics
at all between the etching and readout phases. The
152x152mm holder will accommodate 25 plastics of size
25mm square, and the 203x203mm holder will accommodate
49 plastics of 25mm square. The holders can be
customised at the time of ordering to fit any size of
plastic you are using, and will hold more plastics of
a smaller size.
A photograph of some typical
alpha particle tracks is shown here
Some examples of the TASLIMAGE
software are given here
Systems can
run at a rate of 8
full microscope image
frames per second. This will enable
routine scanning to take around one minute for a 1 square centimetre of scan area.
Our system can read both our
own proprietary format of detector layout, and also
the Autoscan style layout. In both cases the detectors
are fully automatically processed, including ID code
reading, autofocussing and exposure measurement.
Current supply
We have sold over 30 image analysis systems worldwide as either stand alone devices for research or for radon
or neutron dosimetry applications, or as part of our complete detector and
dosimetry laboratory system including etch processing
as well as readout.
The system ships with a manual, and an extensive
online help system.
We
will be pleased to provide detailed quotes, and discuss
your applications in more detail - contact us
here.
©
2005-2008 Track Analysis Systems Ltd. All rights reserved.
TASL, TaslImage, Tastrak, Radosure and the TASL marks are
owned by Track Analysis Systems Ltd and may be registered.
All other trademarks are the property of their
respective owners.
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