Automatic tracking of gold seed markers from CBCT image projections in lung and prostate radiotherapy.

Purpose: To construct a method and software to track gold seed implants in prostate and lung patients undergoing radiotherapy using CBCT image projections.

Methods: A mathematical model was developed in the MatLab (Mathworks, Natick, USA) environment which uses a combination of discreet cosine transforms and filtering to enhance several edge detection methods for identifying and tracking gold seed fiducial markers in images obtained from Varian (Varian Medical Systems, Palo Alto, USA) and Elekta (Kungstensgatan, Sweden) CBCT projections.

Results: Organ motion was captured for 16 prostate patients and 1 lung patient.

Monte Carlo modelling the dosimetric effects of electrode material on diamond detectors.

Diamond detectors for radiation dosimetry were modelled using the EGSnrc Monte Carlo code to investigate the influence of electrode material and detector orientation on the absorbed dose. The small dimensions of the electrode/diamond/electrode detector structure required very thin voxels and the use of non-standard DOSXYZnrc Monte Carlo model parameters. The interface phenomena was investigated by simulating a 6 MV beam and detectors with different electrode materials, namely Al, Ag, Cu and Au, with thickens of 0.

Estimate of organ radiation absorbed doses in clinical CT using the radiation treatment planning system.

Organ absorbed doses in computed tomography (CT) scans can be measured with anatomical phantoms but not inside the human body. In this study, a straightforward method was investigated to estimate organ doses in clinical CT using the radiation treatment planning system (RTPS) and compared them with experimental results of photoluminescence dosemeters (PLD). In a heterogeneous phantom, the average difference between PLD and RTPS values were -5.

Converging stereotactic radiotherapy using kilovoltage X-rays: experimental irradiation of normal rabbit lung and dose-volume analysis with Monte Carlo simulation.

Purpose: To validate the feasibility of developing a radiotherapy unit with kilovoltage X-rays through actual irradiation of live rabbit lungs, and to explore the practical issues anticipated in future clinical application to humans through Monte Carlo dose simulation.

Methods And Materials: A converging stereotactic irradiation unit was developed, consisting of a modified diagnostic computed tomography (CT) scanner. A tiny cylindrical volume in 13 normal rabbit lungs was individually irradiated with single fractional absorbed doses of 15, 30, 45, and 60 Gy.

A Monte Carlo model of an industrial gauge for radiation protection purposes.

The Mahlo Gravimat densitometers/gauges located at the Feltex carpet factory in Christchurch, New Zealand, contain the radionuclide strontium-90 (Sr-90). Accurate dose/dose rate estimation is always an important concern from a radiation protection point of view. The EGSnrc/BEAMnrc Monte Carlo code was used to create a model of one gauge to determination of the radiation dose distributions and dose rates in air from the Sr-90 source within the gauge.