A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources.
A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a (103)Pd source of air-kerma strength 3.4 U (1 U = 1 microGy m(2) h(-1)), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries such as eye applicators for treating macular degeneration.
Sliski
Alan
A
Boston Science, Lincoln, MA, USA. asliski@bostonscience.com
Soares
Christopher
C
Mitch
Michael G
MG
D001918:Brachytherapy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D011829:Radiation Dosage; D015203:Reproducibility of Results; D012588:Scintillation Counting / Q000295:instrumentation* / Q000379:methods; D012680:Sensitivity and Specificity; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation* / Q000379:methods