Publications by authors named "Niki Fitousi"

2 Publications

  • Page 1 of 1

Two-step validation of a Monte Carlo dosimetry framework for general radiology.

Phys Med 2018 Sep 20;53:72-79. Epub 2018 Aug 20.

University of Leuven, Department of Imaging and Pathology, Division of Medical Physics and Quality Assessment, Herestraat 49, 3000 Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000 Leuven, Belgium. Electronic address:

The Monte Carlo technique is considered gold standard when it comes to patient-specific dosimetry. Any newly developed Monte Carlo simulation framework, however, has to be carefully calibrated and validated prior to its use. For many researchers this is a tedious work. We propose a two-step validation procedure for our newly built Monte Carlo framework and provide all input data to make it feasible for future related application by the wider community. The validation was at first performed by benchmarking against simulation data available in literature. The American Association of Physicists in Medicine (AAPM) report of task group 195 (case 2) was considered most appropriate for our application. Secondly, the framework was calibrated and validated against experimental measurements for trunk X-ray imaging protocols using a water phantom. The dose results obtained from all simulations and measurements were compared. Our Monte Carlo framework proved to agree with literature data, by showing a maximal difference below 4% to the AAPM report. The mean difference with the water phantom measurements was around 7%. The statistical uncertainty for clinical applications of the dosimetry model is expected to be within 10%. This makes it reliable for clinical dose calculations in general radiology. Input data and the described procedure allow for the validation of other Monte Carlo frameworks.
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http://dx.doi.org/10.1016/j.ejmp.2018.08.005DOI Listing
September 2018

Patient and staff dosimetry in vertebroplasty.

Spine (Phila Pa 1976) 2006 Nov;31(23):E884-9; discussioin E890

Department of Medical Physics, School of Medicine, University of Patras, Patras, Greece.

Study Design: Eleven vertebroplasty operations were studied in terms of radiation dose.

Objective: Doses to patients and staff associated with vertebroplasty were measured. Occupational doses were compared with the annual dose limits, and the effectiveness of the used radiation protection means was estimated. Patient dose was estimated by means of both surface and effective dose, and the radiation-induced risk was evaluated.

Summary Of Background Data: Vertebroplasty is a recent minimally invasive technique for the restoration of vertebral body fractures. It involves fluoroscopic exposure, and so, it demands dose measurements for both patient and staff exposed to radiation.

Methods: Thermoluminescent dosimeters (TLDs) were placed on the medical personnel and the effective dose was derived. Slow films were placed to patients' skin to measure entrance surface dose. Furthermore, a Rando phantom loaded with TLDs was irradiated under conditions simulating vertebroplasty, in order to estimate effective dose to the patient.

Results: Mean fluoroscopy time was 27.7 minutes. Patient's mean skin dose was 688 mGy, while effective dose was calculated to be 34.45 mGy. It was estimated that the primary operator can perform about 150 vertebroplasty operations annually without exceeding the annual dose constraints, whereas occupational dose can be reduced by 76% using mobile shielding.

Conclusions: Measures have to be taken to reduce patient's skin dose, which, in extreme cases, may be close to deterministic effects threshold. The highest dose rates, recorded during the procedure, were found for primary operator's hands and chest when no shielding was used.
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http://dx.doi.org/10.1097/01.brs.0000244586.02151.18DOI Listing
November 2006
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