May 3, 2012
Innovation: patent applications review
A round-up of the latest international patent applications in radiation therapy.
Automated cyclotron adjustment boosts therapy efficiency
Varian Medical Systems has developed a method to perform efficient, automatic adjustment of cyclotron beam currents across a wide range, enabling proton therapy at multiple depths in the patient in a single treatment session (WO/2012/031299). In one embodiment, efficient adjustment is achieved by attenuating beam current using an electrostatic vertical deflector installed in the inner centre of the cyclotron. The beam current may, for example, be adjusted by applying a high voltage to the electrostatic vertical deflector. Before each treatment, the attenuation curve of the vertical deflector is recorded and used to determine the vertical deflector voltage for the required beam current of each irradiation layer. In another embodiment, a process is provided that allows automated initialization of a cyclotron after overnight or maintenance shutdown.
Luminescent cells provide in situ PDT light source
Researchers at Kansas State University (Manhattan, KS) have come up with a novel means of activating photodynamic therapy (PDT) for treating cancerous cells and tissue (WO/2012/040105). The method involves administering tumour-trophic cells that express a luminescent protein to the patient. A photosensitizing agent is then administered separately, followed by an optional iron chelator. On the day of treatment, a luminogenic substrate corresponding to the luminescent protein is administered to the subject. The substrate reacts with the protein in the vicinity of cancerous tissue to produce light. This light activates the photosensitizing agent, resulting in selective destruction of the cancerous tissue.
Contouring module focuses on radiotherapy planning
Philips Electronics of the Netherlands has invented a contouring module that iteratively adjusts the contours that delineate target and risk regions in a radiotherapy planning image (WO/2012/035463). An intensity-modulation optimization module generates a treatment plan conforming to dose constraints for the target and risk regions delineated by the contours. After each iterative contour adjustment, the contouring module invokes a differential analysis module, which estimates the partial derivatives of an output of the intensity-modulation optimization module with respect to the contour segments, and renders the segments on a display of the planning image. The contour segments are coded based on the estimated partial derivatives, to indicate their impact on the intensity-modulation optimization.
Adaptive active cooling ensures focused ultrasound safety
InSightec of Israel has published details of a thermal treatment method that can be optimized to ensure sufficient thermal dose delivery to tumours while avoiding heat build-up in healthy surrounding tissues (WO/2012/052847). The method involves heating a target tissue, using focused ultrasound, for example, and monitoring a temperature field in a region encompassing both target and non-target tissues. Based on this field, which can be monitored using MRI thermometry or other thermal imaging technique, the temperature of the non-target tissue is actively adjusted, for example by flowing fluid through a heat exchanger in contact with this tissue. The ultrasound focusing parameters can also be adjusted based on the monitored temperature field. The filing also describes a method in which the location of the ultrasound focus is cycled between different targets at different distances from non-target tissue.
Device delivers electron beam shaping for IORT
A tubular applicator for shaping the electron beam of an intraoperative radiation therapy (IORT) system is described by Sordina of Italy (WO/2012/049700). The device comprises a slab with a hole corresponding to the duct of the tubular applicator, through which the electron beam is transmitted, and at least one planar element comprising an upper and a lower plate. At least one of the planar elements is attachable to the slab via a second mechanical coupling, such that the arrangement of the element with respect to the slab can be adjusted to define an aperture of smaller area than that of the applicator's duct. The upper plate of each planar element is made from a sterilizable biocompatible material and the lower plate from a different biocompatible material with a larger atomic number than that of the upper plate. The lower plate thus attenuates X-rays produced by the upper plate. The filing also provides an automatic method for computing the dose distribution emitted from an IORT system through the beam-shaping device.
About the author
Tami Freeman is editor of medicalphysicsweb.