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Measurement of Multi-Slice CT Dose Profile with MOSFET Detectors and CT Dose Profiler Probe

Y Yang*, H Liu , W Zhuo , Y Huang ,


(Monday, 7/15/2019) 9:30 AM - 10:00 AM

Room: Exhibit Hall | Forum 9

Purpose: CTDI100 are not suitable to measure the wide beam CT output, so the aim of this study was to map the longitudinal CT dose profile in the CT helical mode and compare the performance and applicability of MOSFET detectors and CT dose profiler (CTDP) probe.

Methods: The MOSFET dose measurement system (Thomson & Nielsen, Ottawa, Canada) and a CTDP Probe (RTI Electronic, Sweden) were used in this study. The MOSFET dosimeters were placed along the hole in the center and 12 o’clock position of a 32cm CTDI phantom at a 1cm interval to obtain the dose profiles. The CTDP Probe was placed in the same position as MOSFETs. All scans in this study were performed using a Aquilion ONE Cannon CT scanner at 120kVp with 40mm collimation width. CTDI-100IC was calculated based on the measured dose profile and was benchmarked with 100 mm ion chambers.

Results: CTDI100 measured at the center of the phantom of ion chamber, MOSFETs and CTDP probe were 16.01mGy, 15.35mGy and 16.56mGy, respectively. And CTDI100 measured at the12 o’clock of the body phantom of ion chamber, MOSFETs and CTDP probe were 33.28mGy, 32.29mGy and 35.78mGy, respectively. It is obvious that the measurement result at the 12 o’clock position of MOSFET detectors are more consistent with that of the ionization chamber while the measurement result at the center of CTDP probe are more consistent with that of the ionization

Conclusion: Compared with MOSFET detectors, CTDP Probe with plenty of sampling points has advantage in measuring the dose profiles at the center of phantoms. However, for measuring the dose profiles at the peripheral of phantoms, each sampling point of CTDP is affected to the tube angle position. Therefore, it is not so applicable to evaluate the peripheral dose profiles as MOSFET.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by the Natural Science Foundation of China (grant number 11475047)


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