The assessment of tailor-made optical fibre subjected to ionizing radiation

The dosimetric properties of thermoluminescence (TL) dosimeter such as dose response, linearity, sensitivity, fading, minimum detectable dose (MDD), glow curve and reproducibility of optical fibres in comparison with TLD-100 (rod types) have been investigated. The samples used were Dummy Flat Fibre (DFF), Flat Fibre (FF), Photonic Crystal Fibre (PCF), Multi Photonic Crystal Fibre (MPCF) of 2 mm and 220 µm diameter, Photosensitive Flat Fibre (PFF), Single Mode Optical Fibre (SMF), Germanium - doped (Ge), Erbium - doped (Er) and Aluminum doped Thulium (Al: Tm). The TL samples were placed in solid phantom and irradiated with 6, 9 and 12 MeV electrons beam with dose ranging from 1.0 Gy to 4.0 Gy by using linear accelerator (LINAC) machine. Investigations were also conducted for X - rays with mean energies of 30, 60 and 70 kV, and gamma rays (60Co) from 1.0 mGy up to 24.0 Gy. The glow curves were observed between 155 °C to 287 °C. The results of TL dosimeter subjected to 6, 9 and 12 MeV electrons clearly showed that PFF was superior in terms of TL response and sensitivity. This was followed by Ge, DFF, TLD-100, FF, PCF, Er, Al: Tm, MPCF 2 mm and MPCF 220 µm. For X-ray irradiation, the SMF showed 10 and 8 times more sensitive than TLD-100. The MDD obtained from optical fibres subjected to electron irradiation were between 0.53- 0.60 mGy for PFF, 0.78-0.81 mGy for TLD-100, 1.00-1.26 mGy for Ge and 1.44-1.64 mGy for DFF. The results showed that PFF and SMF have great potential to be considered as a radiation dosimeter

Detectability of fibrils by dilation technique in digital mammography

The detectability of fibrils in mammographic phantom images by morphological enhancement was analysed in the present study. Materials that mimic fibrils were imaged by a digital mammography machine at 28 and 29 kVP. The images were processed by a dilation technique to produce second set of images. Receiver operating characteristic analysis was performed to compare the detection performance from the two sets of images. As compared to original images, the 28 kVP's fibrils images from dilation technique become more prominence to be detected by observers. While at 29 kVP only a few observers can found the fibrils images from dilation technique. This study suggests morphological enhancement of mammography image did not increase the detection of low frequency signals of the images

Photon irradiation response of photonic crystal fibres and flat fibres at radiation therapy doses

Radiation effects of photon irradiation in pure Photonic Crystal Fibres (PCF) and Flat fibres (FF) are still much less investigated in thermoluminescense dosimetry (TLD). We have reported the TL response of PCF and FF subjected to 6 MV photon irradiation. The proposed dosimeter shows good linearity at doses ranging from 1 to 4 Gy. The small size of these detectors points to its use as a dosimeter at megavoltage energies, where better tissue-equivalence and the Bragg–Gray cavity theory prevails