ABSTRACT
Optical fibre dosemeter systems based on radioluminescence and optically stimulated luminescence (OSL) from carbon-doped aluminium oxide (Al(2)O(3):C) crystals were developed for in vivo real-time dose rate and absorbed dose measurements in radiotherapy and mammography. A technique was also developed for making ultra-small dosemeter probes that can easily be placed inside patients in radiation treatment. These probes have shown excellent properties in both head and neck intensity-modulated radiation therapy treatment and in mammography. The dose-response of the OSL signal for the new optical fibre dosemeter system showed a repeatability within 0.15% at a dose level of 60 mGy when integrated over 100 s. The temperature dependence in the range 0-45 degrees C showed a reproducibility within 1.3% when the OSL signal was integrated over 100 s.
Subject(s)
Aluminum Oxide/chemistry , Aluminum Oxide/radiation effects , Fiber Optic Technology/instrumentation , Thermoluminescent Dosimetry/instrumentation , Carbon/chemistry , Carbon/radiation effects , Equipment Design , Equipment Failure Analysis , Radiation Dosage , Reproducibility of Results , Sensitivity and Specificity , Thermoluminescent Dosimetry/methodsABSTRACT
This paper analyses the influence of the Cerenkov radiation and other noise sources, the so-called stem effect, on radioluminescence (RL) signals generated in optical fibre Al2O3:C dosemeters used in medical dosimetry. The optical fibre dosemeter consists of a sensitive Al2O3:C crystal coupled to an optical fibre cable that carries the RL and optically stimulated luminescence (OSL) signals generated in the Al2O3:C crystal. During irradiation of the dosemeter, the real-time dose rate can be determined from the RL signal and after irradiation the total dose absorbed is determined from the OSL signal stimulated using a focused green solid-state laser. In particular, the components of the stem effect generated in the fibres were analysed to determine their impact on the RL signal.
Subject(s)
Aluminum Oxide/chemistry , Aluminum Oxide/radiation effects , Artifacts , Models, Chemical , Radiation Protection/instrumentation , Thermoluminescent Dosimetry/instrumentation , Computer Simulation , Dose-Response Relationship, Radiation , Equipment Design , Equipment Failure Analysis , Materials Testing , Radiation Dosage , Radiation Protection/methods , Reproducibility of Results , Sensitivity and Specificity , Thermoluminescent Dosimetry/methodsABSTRACT
A new optical-fibre radiation dosimeter system, based on radioluminescence and optically stimulated luminescence from carbon-doped aluminium oxide, was developed and tested in clinical photon beams. This prototype offers several features, such as a small detector (1 x 1 x 2 mm3), high sensitivity, real-time read-out and the ability to measure both dose rate and absorbed dose. The measurements describing reproducibility and output dependence on dose rate, field size and energy all had standard deviations smaller than 1%. The signal variation with the angle of incidence was smaller than 2% (1 SD). Measurements performed in clinical situations suggest the potential of using this real-time system for in vivo dosimetry in radiotherapy.