Publications by authors named "B Clasie"

Beam position uncertainties along the beam trajectory arise from the accelerator, beamline, and scanning magnets (SMs). They can be monitored in real time, e.g.

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Article Synopsis
  • A first experimental verification of dose-averaged linear energy transfer (LET) optimized treatment plans for proton therapy was conducted at Massachusetts General Hospital using a microdosimeter.
  • Three treatment plans for ependymoma were designed and optimized to reduce LET-weighted doses in the brain stem while still effectively targeting the tumor.
  • The results showed an average reduction in LET in the brain stem by 12%, 19%, and 4%, respectively, for different plan types, confirming that the optimized doses aligned with both simulations and treatment planning system calculations.
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Purpose: This work aims at reviewing challenges and pitfalls in proton facility design related to equipment upgrade or replacement. Proton therapy was initially developed at research institutions in the 1950s which ushered in the use of hospital-based machines in 1990s. We are approaching an era where older commercial machines are reaching the end of their life and require replacement.

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Introduction: Unscheduled machine downtime can cause treatment interruptions and adversely impact patient treatment outcomes. Conventional Quality Assurance (QA) programs of a proton Pencil Beam Scanning (PBS) system ensure its operational performance by keeping the beam parameters within clinical tolerances but often do not reveal the underlying issues of the device prior to a machine malfunction event. In this study, we propose a Predictive Maintenance (PdM) approach that leverages an advanced analytical tool built on a deep neural network to detect treatment delivery machine issues early.

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Background: Pencil beam scanning (PBS) monitoring chambers use an ionization control signal, monitor units (MUs), or gigaprotons (Gp) to irradiate a pencil beam and normalize dose calculations. The nozzle deflects the beam from the nozzle axis by an angle subtended at the source-to-axis distance (τ) from the isocenter. If the angle is not correctly considered in calibrations or calculations, it can lead to systematic errors.

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