Physics in Medicine and Biology, 49 (2004) 2891-2898
Non-invasive determination of the irradiation dose in fingers using
low-frequency EPR
M. Zdravkova, N. Crokart, F. Trompier, N. Beghein, B. Gallez and R.
Debuyst
Several reports in the literature have described the effects of
radiation in workers who exposed their fingers to intense radioactive
sources. The radiation injuries occurring after local exposure to
a high dose (20 to 100 Gy) could lead to the need for amputation.
Follow-up of victims needs to be more rational with a precise knowledge
of the irradiated area that risks tissue degradation and
necrosis. It has been described previously that X-band electron
paramagnetic resonance (EPR) spectroscopy could be used to assess the
dose in irradiated amputated fingers. Here, we propose the use of
low-frequency EPR spectroscopy to evaluate non-invasively the absorbed
dose. Low-frequency microwaves are indeed less absorbed by water
and penetrate more deeply into living material (~ 10mm in tissues using
1 GHz spectrometers). This work presents preliminary results obtained
with baboon and human fingers compared with human dry phalanxes placed
inside a surface-coil resonator. The EPR signal increased
linearly with the dose. The ratio of the slopes of the dry bone
to whole finger linear regression lines was around 5. The
detection limit achievable with the present spectrometer and resonator
is around 60Gy, which is well within the range of accidentally exposed
fingers. It is likely that the detection limit could be improved
in the future, thanks to further technical spectrometer and resonator
developments as well as to appropriate spectrum deconvolution into
native and dosimetric signals.