Bruker e-scan Flashcards
e-scan
It is a bench top EPR (Electron Paramagnetic Resonance) spectrometer dedicated to the evaluation of absorbed dose in alanine dosimeters (either film of pellet). The EPR spectrometer works by measuring the energy level transitions of free radicals at a specific resonant frequency within a variable magnetic field.
free-radicals
unpaired electrons
stray fields
Rad. 127mm-200mm=5mT
Rad. 162mm-330mm=1mT
Rad. 167mm-370mm=0.7mT
Rad. 173mm-410mm=0.5mT
basic user
basic operator
operator user
general purpose operator
o++ user
more advanced operator
qcm user
quality control manager
administrator user
system administrator, full access to all features
pcn
process control number
Import Bridge Calibration
C:\Bruker\e-scan\Dosimetry\Acquisition\SYSCAL
Spectrum Parameters
parameters for dosimeter inserts
.mdb
Microsoft Access database file
backup file
when 800MB is reached
Alanine
is one of several compounds called “amino acids”. Amino acids comprise the building blocks for biological molecules known as proteins. When the alanine is subjected to ionizing radiation it forms a very stable free radical. The alanine free radical produces an EPR signal that is dose dependent, yet is independent of the dose rate, energy type, and is relatively insensitive to temperature and humidity. Thus, alanine dosimetry is equally suited to Gamma, E-beam, or X-ray irradiation
facilities.
Dosimeter insert
contains a carefully measured quantity of a proprietary
Bruker reference marker that also produces an EPR signal. Every scan performed by the e-scan will simultaneously measure the alanine free radical (in an irradiated dosimeter) and the internal reference marker of the dosimeter insert. The intensity value that is correlated with dose is the ratio of the alanine EPR signal to that of the reference marker’s EPR signal.
Irradiation Dose
is determined from a ratio of EPR intensities (alanine free radical / Internal reference marker).
Validation
Validation is a high-level review to determine the conformity of a system, process or product to internally established standards and the appropriateness
of these standards.
Self Test
self test is designed to check your e-scan’s various hardware components for proper function.
Signal-to-Noise
is designed to assure the sensitivity of your e-scan is
adequate for making alanine dosimeter measurements The signal to noise ratio should be greater than 100:1.
Repeatability Test
The repeatability test provides a measure of how consistent the e-scan is at reading the dose from a dosimeter. The test will measure the same dosimeter
100 times and should yield an RSD (relative standard deviation) of < 0.5%.
Reproducibility Test
The reproducibility test measures the consistency of the e-scan when certain changes and interruptions are made during a series of measurements. The test
is nearly identical to the repeatability test and uses the same dosimeter (i.e., 50 kGy film or tapetab). However, during the reproducibility test you will measure the dosimeter only 25 times. (removing and re-inserting either the dosimeter or the dosimeter insert throughout the test.) The reproducibility test should yield an RSD of < 1.0%.
Dosimeter Test
response of a dosimeter over a series of measurements using
Calibration
To make a meaningful dose assessment the dosimeter measurements need to be compared with measurements made using certified dosimeters of known dose. This is achieved by performing the calibration routine which creates a calibration curve and corresponding fit coefficients from measurements made with a set of dosimeters with known certified dose.
Amino Acids
Amino acids comprise the building blocks for biological molecules known as proteins.
