Characterization of a fiber‐optic‐coupled radioluminescent detector for application in the mammography energy range

Abstract

Fiber-optic-coupled radioluminescent (FOC) dosimeters are members of a new family of dosimeters that are finding increased clinical applications. This study provides the first characterization of a Cu doped quartz FOC dosimeter at diagnostic energies, specifically across the range of x-ray energies and intensities used in mammographies. We characterize the calibration factors, linearity, angular dependence, and reproducibility of the FOC dosimeters. The sensitive element of each dosimeter was coupled to a photon counting photomultiplier module via 1 m long optical fibers. A computer controlled interface permitted real-time monitoring of the dosimeter output and rapid data acquisition. The axial-angular responses for all dosimeter models show nearly uniform response without any marked decrease in sensitivity. However, the normal-to-axial angular response showed a marked decrease in sensitivity of about 0 degrees C and 180 degrees C. In most clinical applications, appropriate dosimeter positioning can minimize the contributions of the varying normal-to-axial response. The FOC dosimeters having the greatest sensitive length provided the greatest sensitivity, with greatest to lowest sensitivity observed for 4.0, 1.9, 1.6, and 1.1 mm length sensitive elements. The average sensitivity of the dosimeters varies linearly with sensitive volume (R2=95%) and as a function of tube potential and target/filter combinations, generally exhibiting an increased sensitivity for higher energies. The dosimeter sensitivity as a function of tube potential had an average increase of 4.72 +/- 2.04% for dosimeter models and three target-filter combinations tested (Mo/Mo, Mo/Rh, and Rh/Rh) over a range of 25-31 kVp. All dosimeter models exhibited a linear response (R2 > or = 0.997) to exposure for all target-filter combinations, tube potentials, and tube current-time product stations evaluated and demonstrated reproducibility within 2%. All of the dosimeters examined in this study provided a response adequate for the accurate measurement of doses in clinical mammography applications.

Review of doped silica glass optical fibre: Their TL properties and potential applications in radiation therapy dosimetry

“…Various aspects have been studied (Abdulla et al, 2001;Yusoff et al, 2005;Espinosa et al, 2006;Abdul Rahman et al, 2010a, Abdul Rahman et al, 2010b, Abdul Rahman et al, 2011a, Abdul Rahman et al, 2011b, as for instance, radiation induced attenuation (Huston et al, 2001), radioluminescence (RL) and optically stimulated luminescence (OSL) (Justus et al, 1997;Aznar et al, 2004;Benevides et al, 2007). Useful TL emission has been observed at the radiation levels familiarly applied in high dose radiation-medicine procedures.…”

Validating plastic scintillation detectors for photon dosimetry in the radiologic energy range

“…Some studies [10][11][12] have shown that the dose linearity, reproducibility, and angle independence of PSD are maintained in the diagnostic energy range, but these studies also found a positive variation in the energy response over the energy range of interest. Hyer et al 10 reported an increase of 10% in the PSD response at 15-cm depth owing to beam hardening and scattered radiation with a 120-kVp beam.…”

Embedded structure fiber-optic radiation dosimeter for radiotherapy applications

“…These include thermoluminescent dosimeters (TLDs), silicon diodes, radiochromic films, metal-oxide fieldeffect transistors (MOSFETs) and ionization chambers (ICs) [2][3][4][5][6][7]. TLD detector devices are available as chip, rod or cube types.…”