Organ point dose measurements in clinical multi slice computed tomography (MSCT) examinations with the MOSkin™ radiation dosimeter

Abstract

This study reports on the application of the MOSkin™ dosimeter in MSCT imaging for the real-time measurement of absorbed organ point doses in a tissue-equivalent female anthropomorphic phantom. MOSkin™ dosimeters were placed within the phantom to measure absorbed point organ doses for 2 commonly applied clinical scan protocols, namely the renal calculus scan and the pulmonary embolus scan. Measured organ doses in the imaged field of view were found to be in the dose range 4.7-9.5 mGy and 16.2-27.4 mGy for the renal calculus scan and pulmonary scan protocols respectively. For the derivation of effective dose, using the more recent ICRP 103 tissue weighting factors (w T) compared to that of the ICRP 60 wT resulted in a difference in the derived effective dose by up to 0.8 mSv (-20%) in the renal calculus protocol and up to 1.8 mSv (18%) in the pulmonary embolus protocol. This difference is attributed to the reduced radiosensitivity of the gonads and the increased radiosensitivity of breast tissue in the latest ICRP 103 assigned wT. The results of this study show that the MOSkin™ dosimeter is a useful real-time tool for the direct assessment of organ doses in clinical MSCT examinations.

Assessment of female breast dose for thoracic cone-beam CT using MOSFET dosimeters

“…The MOSFET dosimeters have been recommended by many authors for diagnostic CT dosimetry [ 16 – 19 ]. As the reproducibility of MOSFET dosimeters was closely correlated with the applied dose [ 21 ], the CMRP MOSFETs were calibrated at the dose range of a normal thorax CBCT, yielding a measurement accuracy within 3%.…”

“…The physical performance of this dosimeter was well documented in the literature for external beam radiotherapy [27, 28], interventional radiology procedures [22] and diagnostic radiology dosimetry [16, 17]. …”

“…The p-channel MOSFETs (brand named “MOSkin”) together with a portable reader were supplied by the Center of Medical Radiation Physics (CMRP), University of Wollongong, Australia. The physical performance of this dosimeter was well documented in the literature for external beam radiotherapy [ 27 , 28 ], interventional radiology procedures [ 22 ] and diagnostic radiology dosimetry [ 16 , 17 ].…”

“…The fact that acquiring moderately accurate, reproducible results using TLDs requires a stringent pre-calibration, annealing and post-irradiation readout process hinders their use in the diagnostic radiology clinic. Recently, the utilization of metal oxide semiconductor field effect transistor (MOSFET) technology in CT dosimetry has begun to appear in many peer-reviewed radiology publications [ 16 – 19 ]. Compared with TLDs, the MOSFET dosimeters can offer a fast, simple and inexpensive means to conduct a point dose measurement in radiation beams.…”

Measurement of multi-slice computed tomography dose profile with the Dose Magnifying Glass and the MOSkin radiation dosimeter

“…Table 1 shows the scan parameters used for this study which were designed based on commonly used clinical imaging parameters for diagnostic CT scans. The MOSkin dosimeter, designed and developed at the Centre for Medical Radiation Physics (CMRP), University of Wollongong, Australia, has previously been investigated for applications in radiation therapy (Hardcastle et al, 2008;Kwan et al, 2009) and recently in CT (Lian et al, 2012). It was found to be tissue equivalent at depth in clinical kilovoltage beams (Lian et al, 2011) and was therefore selected as our gold standard absolute dosimeter in this work.…”