Improving dose homogeneity in large breasts by IMRT: efficacy and dosimetric accuracy of different techniques.

Purpose: Evaluation of a simplified intensity-modulated irradiation (IMRT), a three-field (MFT), and a conventional two-tangential-field technique regarding dose homogeneity, target coverage, feasibility and, for the first time, dosimetric reliability in patients with large breasts treated postoperatively for breast cancer on a low-energy linac.

Material And Methods: CT datasets of ten patients with relatively large breast volumes treated for breast cancer were selected. For each patient, four treatment plans were created: low-energy conventional (C-LE), high-energy conventional (C-HE), three-field (MFT), and a two-field aperture-based IMRT technique.

Phantom and in-vivo measurements of dose exposure by image-guided radiotherapy (IGRT): MV portal images vs. kV portal images vs. cone-beam CT.

Purpose: Positioning verification is usually performed with treatment beam (MV) portal images (PI) using an electronic portal imaging device (EPID). A new alternative is the use of a low energy photon source (kV) and an additional EPID mounted to the accelerator gantry. This system may be used for PI or--with rotating gantry--as cone-beam CT (CBCT).

Repositioning accuracy of two different mask systems-3D revisited: comparison using true 3D/3D matching with cone-beam CT.

Purpose: The repositioning accuracy of mask-based fixation systems has been assessed with two-dimensional/two-dimensional or two-dimensional/three-dimensional (3D) matching. We analyzed the accuracy of commercially available head mask systems, using true 3D/3D matching, with X-ray volume imaging and cone-beam CT.

Methods And Materials: Twenty-one patients receiving radiotherapy (intracranial/head-and-neck tumors) were evaluated (14 patients with rigid and 7 with thermoplastic masks).

Radiation enhancement by gemcitabine-mediated cell cycle modulations.

The purpose of this study was to investigate the exact dose dependency and time dependency of the radiation-enhancing effect of gemcitabine (2',2'difluoro desoxycytidine [dFdC]) in in vitro experiments (HeLa cells: cancer of the uterine cervix, #4197 cells: oropharyngeal squamous cell carcinoma), and to correlate this effect with the underlying changes in cell cycle distribution. Cell viability was determined fluorometrically after exposure to dFdC (0-20.0 micro mol/l), irradiation (0-37.

[Combined radiotherapy and gemcitabine. Evaluation of clinical data based on experimental knowledge].

Background: In experimental studies the nucleoside analog Gemcitabine (2',2' difluorodesoxycytidine) clearly demonstrates radiation enhancing properties. After describing the pharmacological Gemcitabine-related data and the clinical studies regarding combined radiochemotherapy and taking under consideration the in-vitro data and the results provided by animal models, this overview is aimed to draw clinically relevant conclusions, resulting in the improvement of treatment approaches.

Materials And Methods: The available literature data regarding the metabolism and the mechanism of action, the evaluation of possible schedules of administration, and combined radiochemotherapy including Gemcitabine has been reviewed.