Energy resolved dosimetry offers a potential path to single detector based proton imaging using scanned proton beams. This is because energy resolved dose functions encrypt the radiological depth at which the measurements are made. When a set of predetermined proton beams 'proton imaging field' are used to deliver a well determined dose distribution in a specific volume, then, at any given depth x of this volume, the behavior of the dose against the energies of the proton imaging field is unique and characterizes the depth x. This concept applies directly to proton therapy scanning delivery methods (pencil beam scanning and uniform scanning) and it can be extended to the proton therapy passive delivery methods (single and double scattering) if the delivery of the irradiation is time-controlled with a known time-energy relationship. To derive the water equivalent path length (WEPL) from the energy resolved dose measurement, one may proceed in two different ways. A first method is by matching the measured energy resolved dose function to a pre-established calibration database of the behavior of the energy resolved dose in water, measured over the entire range of radiological depths with at least 1 mm spatial resolution. This calibration database can also be made specific to the patient if computed using the patient x-CT data. A second method to determine the WEPL is by using the empirical relationships between the WEPL and the integral dose or the depth at 80% of the proximal fall off of the energy resolved dose functions in water. In this note, we establish the evidence of the fundamental relationship between the energy resolved dose and the WEPL at the depth of the measurement. Then, we illustrate this relationship with experimental data and discuss its imaging dynamic range for 230 MeV protons.

measurements. We provide an overview of the magnetic components, beam transport, cyclotron, beam and treatment related parameters necessary for the development of a present day optical model of the facility. This work represents the first comprehensive study of the CCC facility to date, as a basis to determine input beam parameters to accurately simulate and completely characterise the beamline.

Knowledge of the beam properties in proton therapy through beam monitoring is essential, ensuring an effective dose delivery to the patient. In clinical practice, currently used interceptive ionisation chambers require daily calibration and suffer from a slow response time.A new non-invasive method for dose online monitoring is under development based on the silicon multi-strip sensor LHCb VELO (VErtex LOcator), originally used for the LHCb experiment at CERN. The proposed method relies on proton beam halo measurements. Several changes in the system setup were necessary to operate the VELO module as a standalone system outside of the LHC environment and are described in this paper. A new cooling, venting and positioning system was designed. Several hardware and software changes realised a synchronised readout with a locally constructed Faraday Cup and the RF frequency of a medical cyclotron with quasi-online monitoring. The adapted VELO module will be integrated at the 60 MeV proton therapy beamline at the Clatterbridge Cancer Centre (CCC), UK and the capability as a beam monitor will be assessed by measuring the beam current and by monitoring the beam profile along the beamline in spring 2019.