Non invasive determination of the irradiation dose in fingers using low frequency EPR
M. Zdravkova, N. Crokarta, F. Trompier, N. Beghein, B. Gallez and R. Debuyst Non invasive determination of the irradiation dose in fingers using low frequency EPR, Physics in Medicine and Biology 49 2891-2898 (2004). DRPH-PUB-2003/141 Juin 2004
Several reports in the litterature described the overexposure of workers who exposed their fingers to intense radioactive sources. The radiation injuries occuring after exposure to a local high dose (20 to 100 Gy) could lead to the need of amputation. The follow-up of victims should be more rational with a precise knowledge of the irradiated area which risks tissue degradation and necrosis. It was previously described that X-Band 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 (~10 mm in tissues using 1 GHz spectrometers). This work presents preliminary results obtained with baboon fingers and human fingers compared with 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 is around five. The detection limit achievable with the present spectrometer and resonator is around 60 Gy which is well in 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 thanks to appropriate spectrum deconvolution into native and dosimetric signals.