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This work details a Compton-scattering-based methodology, referred to as Backscatter Gating (BSG), for characterizing the time, energy, and position resolutions of long form factor organic scintillators using a single, fairly minimal measurement setup. Such a method can ease the experimental burden in scenarios where many such scintillator elements may need to be individually characterized before assembly into a larger detector system. A thorough theoretical exploration of the systematic parameters is provided, and the BSG method is then demonstrated by a series of experimental measurements. This “complete” characterization via the BSG method is novel, having previously been used primarily for energy resolution characterization. The method also allows for determination of the assembled scintillator’s technical attenuation length and provides a means of verifying the presence or absence of flaws within the scintillator or its optical coupling.

Prompt Gamma-ray Spectroscopy (PGS) in conjunction with the Monte Carlo Library Least Squares (MCLLS) approach was investigated for the purposes of range monitoring in proton therapy through Monte Carlo simulations. Prompt gamma-rays are produced during treatment and can be correlated to the range of the proton beam in the tissue. In contrast to established approaches, MCLLS does not rely on the identification of specific photopeaks. Instead it treats each individual constituent as a library spectrum and calculates coefficients for each spectrum, and therefore takes both the photopeaks and the Compton continuum into account. It can thus be applied to organic scintillators traditionally not used for energy spectroscopy due to their low Z number and density. Preliminary results demonstrate that the proposed approach returns a strong linear correlation between the range of the primary proton beam and the calculated library coefficients, depending on the composition of libraries. This can be exploited for range monitoring.

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models. The results indicate that range shifts of 1 mm can be detected at relatively low proton intensities (6 million/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context range verification in PT.

Prompt Gamma-ray Spectroscopy (PGS) in conjunction with the Monte Carlo Library Least Squares (MCLLS) approach was investigated for the purposes of range monitoring in proton therapy through Monte Carlo simulations. Prompt gamma-rays are produced during treatment and can be correlated to the range of the proton beam in the tissue. In contrast to established approaches, MCLLS does not rely on the identification of specific photopeaks. Instead it treats each individual constituent as a library spectrum and calculates coefficients for each spectrum, and therefore takes both the photopeaks and the Compton continuum into account. It can thus be applied to organic scintillators traditionally not used for energy spectroscopy due to their low Z number and density. Preliminary results demonstrate that the proposed approach returns a strong linear correlation between the range of the primary proton beam and the calculated library coefficients, depending on the composition of libraries. This can be exploited for range monitoring.

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models. The results indicate that range shifts of 1 mm can be detected at relatively low proton intensities (6 million/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context range verification in PT.

Due to its high sensitivity to anatomical changes, particle therapy will only unfold its full potential together with a functioning online range verification. We present a detector concept making use of a large fraction of the secondary particles available by hybrid prompt gamma-ray and fast neutron imaging. The system is expected to exhibit a high detection sensitivity to these particles, a high time, energy and position resolution, excellent pulse shape discrimination, and a small footprint. It comprises a quasi-monolithic organic detector array consisting of novel organic scintillators with dual-ended silicon photomultiplier light read-out and fast digitizers. The reconstruction of the proton range from the events registered by the detector is based on gamma/neutron scatter kinematics, cone back-projection and maximum likelihood expectation maximization. Multiple studies are currently ongoing investigating the feasibility of this concept on an experimental and simulation level. A first Monte Carlo simulation study involving realistic patient data and an idealized detector has revealed that a range-shift sensitivity of 1 mm per spot is attainable for clinical spot weights. These results demonstrate the potential of particle treatment verification by fast neutrons and prompt gamma-rays and strengthen the potential of this hybrid system for clinical application.

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models. The results indicate that range shifts of 1 mm can be detected at relatively low proton intensities (6 million/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context range verification in PT.

Due to its high sensitivity to anatomical changes, particle therapy will only unfold its full potential together with a functioning online range verification. We present a detector concept making use of a large fraction of the secondary particles available by hybrid prompt gamma-ray and fast neutron imaging. The system is expected to exhibit a high detection sensitivity to these particles, a high time, energy and position resolution, excellent pulse shape discrimination, and a small footprint. It comprises a quasi-monolithic organic detector array consisting of novel organic scintillators with dual-ended silicon photomultiplier light read-out and fast digitizers. The reconstruction of the proton range from the events registered by the detector is based on gamma/neutron scatter kinematics, cone back-projection and maximum likelihood expectation maximization. Multiple studies are currently ongoing investigating the feasibility of this concept on an experimental and simulation level. A first Monte Carlo simulation study involving realistic patient data and an idealized detector has revealed that a range-shift sensitivity of 1 mm per spot is attainable for clinical spot weights. These results demonstrate the potential of particle treatment verification by fast neutrons and prompt gamma-rays and strengthen the potential of this hybrid system for clinical application.

Particle therapy (PT) used for cancer treatment can spare healthy tissue and reduce treatment toxicity. However, full exploitation of the dosimetric advantages of PT is not yet possible due to range uncertainties, warranting development of range-monitoring techniques. This study proposes a novel range-monitoring technique introducing the yet unexplored concept of simultaneous detection and imaging of fast neutrons and prompt-gamma rays produced in beam-tissue interactions. A quasi-monolithic organic detector array is proposed, and its feasibility for detecting range shifts in the context of proton therapy is explored through Monte Carlo simulations of realistic patient models. The results indicate that range shifts of 1 mm can be detected at relatively low proton intensities (6 million/spot) when spatial information obtained through imaging of both particle species are used simultaneously. This study lays the foundation for multi-particle detection and imaging systems in the context range verification in PT.

Particle therapy is a modality for treating cancer using ionizing radiation from, e.g., protons or carbon ions. A growing number of patients worldwide receive particle therapy as a part of their cancer treatment due to its dosimetric advantages over the more conventional external beam radiotherapy using photons. The finite range of particles in tissue results in sparing of healthy tissue surrounding the tumour and thereby a reduced risk of adverse effects compared to conventional treatment. This opens possibilities for a more intensified treatment by dose escalation to the tumour and thereby an increased probability for controlling the disease. However, charged particles, when used for external beam radiotherapy, are much less forgiving than photons in case of treatment deviations. Treatment deviations may be caused by (1) sensitivity of charged particles to anatomical or density changes along their radiological path in the patient, e.g., due to organ motion or tumour shrinkage and (2) uncertainties associated with the estimation of the exact position of the Bragg-peak (maximum dose deposition) in tissue, e.g., due to uncertainties in the estimation of stopping power ratios. Collectively, these are referred to as “range uncertainties”. The most important consequence of range uncertainties is that the tissue sparing potential of charged particles cannot be fully exploited. Therefore, there is an urgent need for reliable and robust treatment verification systems that can identify potential treatment deviations in real-time. Despite recent advances in state-of-the-art prompt gamma-ray imaging, spectroscopy and timing systems as well as in-beam and offline PET imaging systems, the development of treatment verification systems still lags and as such, there is no system yet in wide routine clinical use. Common to all existing solutions is the fact that they rely on a single feature of a single particle species and will therefore suffer from limited counting statistics. Th

Particle therapy is a modality for treating cancer using ionizing radiation from, e.g., protons or carbon ions. A growing number of patients worldwide receive particle therapy as a part of their cancer treatment due to its dosimetric advantages over the more conventional external beam radiotherapy using photons. The finite range of particles in tissue results in sparing of healthy tissue surrounding the tumour and thereby a reduced risk of adverse effects compared to conventional treatment. This opens possibilities for a more intensified treatment by dose escalation to the tumour and thereby an increased probability for controlling the disease. However, charged particles, when used for external beam radiotherapy, are much less forgiving than photons in case of treatment deviations. Treatment deviations may be caused by (1) sensitivity of charged particles to anatomical or density changes along their radiological path in the patient, e.g., due to organ motion or tumour shrinkage and (2) uncertainties associated with the estimation of the exact position of the Bragg-peak (maximum dose deposition) in tissue, e.g., due to uncertainties in the estimation of stopping power ratios. Collectively, these are referred to as “range uncertainties”. The most important consequence of range uncertainties is that the tissue sparing potential of charged particles cannot be fully exploited. Therefore, there is an urgent need for reliable and robust treatment verification systems that can identify potential treatment deviations in real-time. Despite recent advances in state-of-the-art prompt gamma-ray imaging, spectroscopy and timing systems as well as in-beam and offline PET imaging systems, the development of treatment verification systems still lags and as such, there is no system yet in wide routine clinical use. Common to all existing solutions is the fact that they rely on a single feature of a single particle species and will therefore suffer from limited counting statistics. Th