The influence of daily imaging and target margin reduction on secondary cancer risk in image-guided and adaptive proton therapy.

. Image-guided and adaptive proton therapy rely on daily CBCT or CT imaging, which increases radiation dose and radiation-induced cancer risk. Online adaptation however also reduces setup uncertainty, and the additional risk might be compensated by reducing the setup robustness margin.

Feasibility of interleaved multislice averaged magnetization inversion-recovery acquisitions of the spinal cord.

Purpose: To establish an interleaved multislice variant of the averaged magnetization inversion-recovery acquisitions (AMIRA) approach for 2D spinal cord imaging with increased acquisition efficiency compared with the conventional 2D single-slice approach(es), and to determine essential prerequisites for a working interleaved multislice AMIRA approach in practice.

Methods: The general AMIRA concept is based on an inversion recovery-prepared, segmented, and time-limited cine balanced SSFP sequence, generating images of different contrast. For AMIRA imaging of multiple, independent slices in a 2D interleaved fashion, a slice loop within the acquisition loops was programmed.

Impact of internal target volume definition for pencil beam scanned proton treatment planning in the presence of respiratory motion variability for lung cancer: A proof of concept.

Purpose: Motion management is crucial in scanned proton therapy for mobile tumours. Current motion mitigation approaches rely on single 4DCTs before treatment, ignoring respiratory variability. We investigate the consequences of respiratory variations on internal target volumes (ITV) definition and motion mitigation efficacy, and propose a probabilistic ITV based on 4DMRI.

Micron-sized PFOB liquid core droplets stabilized with tailored-made perfluorinated surfactants as a new class of endovascular sono-sensitizers for focused ultrasound thermotherapy.

The purpose of this study was to develop micron-sized droplet emulsions able to increase the heat deposition of high intensity focused ultrasound (HIFU), aiming to accelerate the tumour ablation in highly perfused organs with reduced side effects. The investigated droplets consisted of a perfluorooctyl bromide (PFOB) core coated with a biocompatible fluorinated surfactant called F-TAC. The novelty of this work relies on the use, for this application, of a high boiling point perfluorocarbon core (142 °C), combined with an in-house fluorinated surfactant to formulate the emulsion, yielding quasi-reversible strong interactions between the HIFU beam and the droplets.

Molecular oxygen loading in candidate theranostic droplets stabilized with biocompatible fluorinated surfactants: Particle size effect and application to in situF MRI mapping of oxygen partial pressure.

Objective: Perfluorocarbon nano- and micron-sized emulsions are a new field of investigation in cancer treatment due to their ability to be used as imaging contrast agents, or as delivery vectors for pharmaceuticals. They also demonstrated capability to enhance the efficiency of high intensity focused ultrasound thermo-therapy. In the context of new biomedical applications we investigated perfluorooctyl bromide (PFOB) theranostic droplets using F NMR.

Ultrasound-driven 4D MRI.

We present an ultrasound-driven 4D magnetic resonance imaging (US-4DMRI) method for respiratory motion imaging in the thorax and abdomen. The proposed US-4DMRI comes along with a high temporal resolution, and allows for organ motion imaging beyond a single respiratory cycle. With the availability of the US surrogate both inside and outside the MR bore, 4D MR images can be reconstructed for 4D treatment planning and online respiratory motion prediction during radiotherapy.

Hybrid ultrasound-MR guided HIFU treatment method with 3D motion compensation.

Purpose: Treatments using high-intensity focused ultrasound (HIFU) in the abdominal region remain challenging as a result of respiratory organ motion. A novel method is described here to achieve 3D motion-compensated ultrasound (US) MR-guided HIFU therapy using simultaneous ultrasound and MRI.

Methods: A truly hybrid US-MR-guided HIFU method was used to plan and control the treatment.

Model-guided respiratory organ motion prediction of the liver from 2D ultrasound.

With the availability of new and more accurate tumour treatment modalities such as high-intensity focused ultrasound or proton therapy, accurate target location prediction has become a key issue. Various approaches for diverse application scenarios have been proposed over the last decade. Whereas external surrogate markers such as a breathing belt work to some extent, knowledge about the internal motion of the organs inherently provides more accurate results.

Simultaneous acquisition of image and navigator slices using CAIPIRINHA for 4D MRI.

Purpose: Respiratory organ motion is still the major challenge of various image-guided treatments in the abdomen. Dynamic organ motion tracking, necessary for the treatment control, can be performed with volumetric time-resolved MRI that sequentially acquires one image and one navigator slice. Here, a novel imaging method is proposed for truly simultaneous high temporal resolution acquisition.

Real-time method for motion-compensated MR thermometry and MRgHIFU treatment in abdominal organs.

Purpose: Magnetic resonance-guided high-intensity focused ultrasound is considered to be a promising treatment for localized cancer in abdominal organs such as liver, pancreas, or kidney. Abdominal motion, anatomical arrangement, and required sustained sonication are the main challenges.

Methods: MR acquisition consisted of thermometry performed with segmented gradient-recalled echo echo-planar imaging, and a segment-based one-dimensional MR navigator parallel to the main axis of motion to track the organ motion.

Hybrid ultrasound/magnetic resonance simultaneous acquisition and image fusion for motion monitoring in the upper abdomen.

Objectives: The combination of ultrasound (US) and magnetic resonance imaging (MRI) may provide a complementary description of the investigated anatomy, together with improved guidance and assessment of image-guided therapies. The aim of the present study was to integrate a clinical setup for simultaneous US and magnetic resonance (MR) acquisition to obtain synchronized monitoring of liver motion. The feasibility of this hybrid imaging and the precision of image fusion were evaluated.