d'apprentissage qui sont associées aux meilleures augmentations des résultats parmi les étudiants qui se spécialisent en biologie et ceux qui poursuivent d'autres spécialisations et nous suggérons la manière dont ces résultats peuvent servir à informer les techniques pédagogiques afin que celles-ci puissent bénéficier à tous les étudiants, quel que soit leur domaine de spécialisation, pour les cours de l'avenir.

In hadrontherapy, particularly carbon ion radiation therapy, a characteristic dose distribution precisely delivers maximum dose at the beam endpoint, or Bragg peak, with relatively low dose to the surrounding tissue. As the position of the Bragg peak is highly dependent on patient anatomy and physiology, precise range verification techniques are needed to ensure that the prescribed dose is properly targeted to tumours while sparing healthy tissue. We simulated treatments of a homogeneous phantom using Geant4, and applied a novel Interaction Vertex Imaging (IVI) reconstruction, combining single-particle reconstruction with a coincidence technique, and using a software filter to reduce uncertainty introduced by straggling and multiple scattering in the target. Interaction vertices generated by the most precise Triangulation IVI method were localized to an average of 3.5 mm from the true position of the reaction, simulating a realistic charged particle detection system. No event-byevent information from a beam tracking detector was used in reconstruction. Filtered longitudinal vertex distributions were fit to logistic functions, characterizing the distal edge closest to the Bragg peak. Comparing the position of this distal edge between simulations allowed us to accurately determine if two treatments correctly targeted the same depth. After performing a linear calibration, the depth difference between two treatments could be determined with sub-millimeter precision under clinical conditions (10 6 -10 7 incident 12 C ions), allowing range verification to be performed for each depth setting in a pencil beam scanned treatment plan.

Heavy-ion therapy, particularly using scanned (active) beam delivery, provides a precise and highly conformal dose distribution, with maximum dose deposition for each pencil beam at its endpoint (Bragg peak), and low entrance and exit dose. To take full advantage of this precision, robust range verification methods are required; these methods ensure that the Bragg peak is positioned correctly in the patient and the dose is delivered as prescribed. Relative range verification allows intra-fraction monitoring of Bragg peak spacing to ensure full coverage with each fraction, as well as inter-fraction monitoring to ensure all fractions are delivered consistently. To validate the proposed filtered Interaction Vertex Imaging method for relative range verification, a 16O beam was used to deliver 12 Bragg peak positions in a 40 mm poly-(methyl methacrylate) phantom. Secondary particles produced in the phantom were monitored using position-sensitive silicon detectors. Events recorded on these detectors, along with a measurement of the treatment beam axis, were used to reconstruct the sites of origin of these secondary particles in the phantom. The distal edge of the depth distribution of these reconstructed points was determined with logistic fits, and the translation in depth required to minimize the χ2 statistic between these fits was used to compute the range shift between any two Bragg peak positions. In all cases, the range shift was determined with sub-millimeter precision, to a standard deviation of the mean of 220(10) μm. This result validates filtered Interaction Vertex Imaging as a reliable relative range verification method, which should be capable of monitoring each energy step in each fraction of a scanned heavy-ion treatment plan.