At the National Institute of Radiological Sciences (NIRS), we have been developing the rotating-gantry system for the carbon-ion radiotherapy. This system is equipped with a three-dimensional pencil beam scanning irradiation system. To ensure the treatment quality, calibration of the primary dose monitor, range check, dose rate check, machine safety check, and some mechanical tests should be pe...

BACKGROUND Radiographically guided investigations may be associated with excessive radiation exposure, which may cause skin injuries. The purpose of this study was to develop and test a system that measures in real time the dose applied to each 1-cm(2) area of skin, taking into account the movement of the x-ray source and changes in the beam characteristics. The goal of such a system is to help...

We have proposed four dimensional (4D) digitally reconstructed radiography (DRR) for verifying a lung tumor position during volumetric modulated arc therapy (VMAT). An internal target volume (ITV) was defined based on two clinical target volumes (CTVs) delineated on maximum exhalation and maximum inhalation images acquired by 4D planning computed tomography (CT). A planning target volume (PTV) ...

Background and purposeWe present the first implementation of Adaptive 4D cone beam CT (4DCBCT) that adapts image hardware (gantry rotation speed kV projections) in response to patient’s real-time respiratory signal. 4DCBCT was applied on lung cancer patients reduce scan time imaging dose ADaptive Acquisition for Personalised Thoracic (ADAPT) trial.Materials methodsThe ADAPT technology measures ...

When optimizing variable dose rate VMAT (VDR) beams, the leaf positions and the MU of each control point are optimized simultaneously (Figure 1). Since the MU is not allowed to be individually optimized for each control point for a constant dose rate VMAT (CDR) beam (Figure 2), it is likely that the plan quality is reduced compared to a VDR beam with the same angle settings. To obtain a good qu...

Treatment planning in radiosurgery and radiation therapy involves a large number of medical and technical constraints. The main technical constraints stem from the gantry kinematics and the type of collimator available. The gantry kinematics (i.e. number and spatial arrangement of movable joint axes) determines the type of motion which can be performed by the therapeutic beam. The collimator de...

Machine performance check (MPC) is an automated and integrated image-based tool for verification of beam and geometric performance of the TrueBeam linac. The aims of the study were to evaluate the performance of the MPC geometric tests relevant to beam collimation (MLC and jaws) and mechanical systems (gantry and collimator). Evaluation was performed by comparing MPC to QA tests performed routi...

An algorithm for optimizing beam orientations and beam weights for conformal radiotherapy has been developed. The algorithm models the optimization of beam orientations and beam weights as a problem of mixed integer linear programming (MILP), and optimizes the beam orientations and beam weights simultaneously. The application process of the algorithm has four steps: (a) prepare a pool of beam o...

A multiple-slit collimator (MSC) design was introduced for scatter reduction in cone-beam computed tomography (CBCT). Unlike most other collimators, the open and closed septa of the proposed MSC are placed in an equi-angular interval on a circular track of the central sagittal plane. Therefore, one gantry rotation provides only the half of necessary dataset and two gantry rotations are needed t...

PURPOSE To investigate various issues for clinical implementation of aSi EPID panels for IMRT/VMAT QA. METHODS Six linacs are used in our clinic for EPID-based plan QA; two Varian Truebeams, two Varian 2100 series, two Elekta Infiniti series. Multiple corrections must be accounted for in the calibration of each panel for dosimetric use. Varian aSi panels are calibrated with standard dark fiel...