Leksell Gamma Knife® IconTM with integrated Cone Beam CT (CBCT) system provides increased workflow flexibility with e.g. planning on frameless images and subsequent frameless dose delivery. The stereotactic reference is given by the CBCT images taken prior to treatment. Co-registration of the planning image volume with the CBCT volume gives the transformation mapping of the planned isocenter po...

BACKGROUND The standard clinical protocol of image-guided IMRT for prostate carcinoma introduces isocenter relocation to restore the conformity of the multi-leaf collimator (MLC) segments to the target as seen in the cone-beam CT on the day of treatment. The large interfractional deformations of the clinical target volume (CTV) still require introduction of safety margins which leads to undesir...

The purpose of this study was to describe our experience with 1.0T MR-SIM including characterization, quality assurance (QA) program, and features necessary for treatment planning. Staffing, safety, and patient screening procedures were developed. Utilization of an external laser positioning system (ELPS) and MR-compatible couchtop were illustrated. Spatial and volumetric analyses were conducte...

In this study, we present an algorithm for three-dimensional (3-D) dose reconstruction using portal images obtained with an electronic portal imaging device (EPID). For this purpose an algorithm for 2-D dose reconstruction, which was previously developed in our institution, was adapted. The external contour of the patient was used to correct for absorption of primary photons, but the presence o...

The Delta(4DVH) Anatomy 3D quality assurance (QA) system (ScandiDos), which converts the measured detector dose into the dose distribution in the patient geometry was evaluated. It allows a direct comparison of the calculated 3D dose with the measured back-projected dose. In total, 16 static and 16 volumetric-modulated arc therapy (VMAT) fields were planned using four different energies. Isocen...

BACKGROUND Intensity-modulated radiation therapy (IMRT) is a widely accepted method for radiation treatment to provide a prescribed and uniform dose to the target volume and a minimum dose to normal tissues that is dependent on the IMRT software and the treatment machine. We examined the variation in IMRT dose prescription, treatment planning, dose recording, and dose delivery among cancer pati...

We describe the displacement of the beam-axis from the planning isocenter in clinical situations during three-dimensional conformal radiosurgery using an Acculeaf bi-directional micro-multileaf collimator. The displacements were recorded for 64 ports using a video imaging system and a stereotactic arc. The mean displacement was 0.41+/-0.25 mm.

Medical linear accelerators are one of the most widespread methods for cancer treatment. Despite their advantages, unwanted photoneutrons are produced by high energy linacs. This photoneutrons are as undesired doses to patients and a significant problem for radiation protection of the staffs and patients. Photoneutrons radiological risk must be evaluated because of their high LET and range.in o...