Particle therapy planning exploits MR imaging
ViewRay has published details of particle therapy planning and treatment utilizing MRI data (WO/2017/151662). The process involves receiving radiation therapy prescription information and the patient's MRI data, and using these to determine a treatment plan for use with a particle beam. This plan can utilize the prescription and MRI data to account for interaction properties of soft tissues in the patient through which the particle beam passes. The MRI data may be provided by an MRI system integrated with the particle therapy system. In such cases, MRI data acquired during treatment may also be utilized to modify or optimize the particle therapy.

Probing technique promises accurate range determination
A University of Texas research team has devised a way to directly determine in vivo beam range during particle therapy using the therapeutic beam (WO/2017/132341). First, a configuration is determined for one or more probing spots. Each probing spot, which can be provided by an at least partially therapeutic beam (of 2-20 Gy or greater), corresponds to a planned radiation dose target within the tumour. At least one therapeutic beam is delivered to the tumour volume, during which, one or more images are captured to provide an indication of the range of the probing spots. As the spots are generated using a higher dose than used for conventional imaging, they can be more easily observed from the images, allowing for accurate range determination. Additionally, targeting the probing spots within the tumour interior reduces the risk of delivering dose to sensitive tissue - because even if the dose is delivered to a location other than that location, it is likely to remain contained within the tumour volume.

Imaging system tackles motion during radiotherapy
Elekta has disclosed systems and methods for managing patient motion during image-guided radiotherapy (WO/2017/134482). Such a system may include an image acquisition device, a radiotherapy device and a processor. The processor controls the image acquisition device to acquire at least one 2D image that includes a cross-sectional image of an anatomical region-of-interest in the patient. The processor may also be configured to perform automatic contouring in each 2D image, to extract a set of contour elements segmenting the cross-sectional image of the region-of-interest. The processor may be further configured to match this set of contour elements to a 3D surface image of the region-of-interest, to determine its motion and control radiation delivery based on this determined motion.

Toroidal bending magnets create lighter, simpler gantries
Existing gantry designs for proton and carbon ion therapy are based upon dipole-type bending magnets, necessitating either a large amount of external ferromagnetic shielding or a second set of coils with reversed field to reduce or eliminate the fringe magnetic field from the dipole. Now, MIT researchers have published details of toroidal superconducting magnets that can be used as lightweight rotating bending magnets in hadron therapy gantries (WO/2016/138083). The toroidal bending magnets are self-shielded and do not require ferromagnetic material for field modification or shielding, decreasing both the magnet system weight, as well as overall gantry weight. Achromatic magnets (which can compensate for varying beam energy) can be made by combining two of these bending magnets. The simple geometry may allow the use of higher fields, making it suitable for carbon, as well as proton therapy.

Particle therapy apparatus offers reduced site area
Mitsubishi Electric has developed a heavy particle radiotherapy apparatus with reduced site area, by combining a superconducting synchrotron accelerator with a circular accelerator that uses the phase stability principle (WO/2017/145259). The apparatus includes: an ion source that generates pre-conversion charged particles; an injector (the circular accelerator) that initially accelerates these particles to low energies; and a superconducting synchrotron that accelerates converted charged particles, which have a different number of valence electrons, to high energies. A positive ion charge-conversion device converts the pre-conversion particles into the converted charged particles. The synchrotron uses a superconducting magnet that has a superconducting coil as a bending magnet. The ion source and circular accelerator are arranged on an inner peripheral side of the synchrotron.

Pre-optimization scheme predicts clinical achievability
In patent application WO/2017/153211, Philips describes a pre-optimization method for rapid prediction of the achievability of clinical goals in intensity-modulated radiation therapy (IMRT). An achievability estimate is computed for an IMRT geometry including a target volume, an organ-at-risk (OAR) and at least one radiation beam. Namely, a geometric complexity (GC) metric is computed that compares the number of radiation beamlets available in the IMRT geometry for irradiating the target volume and the number of these beamlets that also pass through the OAR. The ratio of the GC metric for this IMRT geometry and for a reference IMRT geometry (for which an IMRT plan is achievable) is then computed. If the clinician is satisfied with this estimate then optimization of an IMRT plan for the IMRT geometry is performed. Alternatively, a reference IMRT geometry is selected by comparing the GC metric with GC metrics of past IMRT plans.