Relative dosimetry measurements in kilovoltage X-rays with OSLDs

AbstractDosimetry for kilovoltage X-ray units requires a careful choice of equipment due a typically high energy dependence of standard detectors. The use of optically stimulated luminescence detectors (OSLDs) for in-vivo dosimetry and the measurement of relative output factors is investigated in this study. Supralinearity and the suitability of OSLDs for relative dose measurements are determined for the Landauer nanoDot OSLD system (Landauer, Inc., Greenwood, IL). OSLDs were found to exhibit supralinearity for therapeutic doses in kV X-rays, with the effect more pronounced in lower energy beams. Relative lead cutout factors measured with OSLDs were well within 5% of published values. OSLD measurements of applicator factors at the surface of a water phantom showed a systematic offset (>  + 5%) to derived values and values measured with a PTW 23342 soft X-ray ionisation chamber (PTW, Freiburg, Germany), due to the change in source-to-skin distance (SSD) between the applicators used in this study. OSLDs are suitable for relative dosimetry in kilovoltage beams between 80 and 120  kVp when the SSD similar to the calibration/reference conditions.
Source: Australasian Physical and Engineering Sciences in Medicine - Category: Biomedical Engineering Source Type: research