Spread-out Bragg peak measurements using a compact quality assurance range calorimeter at the Clatterbridge cancer centre

Objective. The superior dose conformity provided by proton therapy relative to conventional x-ray radiotherapy necessitates more rigorous quality assurance (QA) procedures to ensure optimal patient safety. Practically however, time-constraints prevent comprehensive measurements to be made of the proton range in water: a key parameter in ensuring accurate treatment delivery. / Approach. A novel scintillator-based device for fast, accurate water-equivalent proton range QA measurements for ocular proton therapy is presented. Experiments were conducted using a compact detector prototype, the quality assurance range calorimeter (QuARC), at the Clatterbridge cancer centre (CCC) in Wirral, UK for the measurement of pristine and spread-out Bragg peaks (SOBPs). The QuARC uses a series of 14 optically-isolated 100 × 100 × 2.85 mm polystyrene scintillator sheets, read out by a series of photodiodes. The detector system is housed in a custom 3D-printed enclosure mounted directly to the nozzle and a numerical model was used to fit measured depth-light curves and correct for scintillator light quenching. / Main results. Measurements of the pristine 60 MeV proton Bragg curve found the QuARC able to measure proton ranges accurate to 0.2 mm and reduced QA measurement times from several minutes down to a few seconds. A new framework of the quenching model was deployed to successfully fit depth-light curves of SOBPs with similar range accuracy. / Significance. The speed, range accuracy and simplicity of the QuARC make the device a promising candidate for ocular proton range QA. Further work to investigate the performance of SOBP fitting at higher energies/greater depths is warranted

Coulomb dissociation of O-16 into He-4 and C-12

We measured the Coulomb dissociation of O-16 into He-4 and C-12 within the FAIR Phase-0 program at GSI Helmholtzzentrum fur Schwerionenforschung Darmstadt, Germany. From this we will extract the photon dissociation cross section O-16(alpha,gamma)C-12, which is the time reversed reaction to C-12(alpha,gamma)O-16. With this indirect method, we aim to improve on the accuracy of the experimental data at lower energies than measured so far. The expected low cross section for the Coulomb dissociation reaction and close magnetic rigidity of beam and fragments demand a high precision measurement. Hence, new detector systems were built and radical changes to the (RB)-B-3 setup were necessary to cope with the high-intensity O-16 beam. All tracking detectors were designed to let the unreacted O-16 ions pass, while detecting the C-12 and He-4

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Prompt gamma-ray imaging of nanoparticles for in vivo range verification in proton therapy

Proton therapy is an emerging modality for cancer treatment that induces a better dose con- formation, compared to traditional photon radiotherapy. In vivo range verification techniques are required to fully exploit the advantages of proton therapy. In the past few years, the use of nanoparticles as dose enhancers has increased due to their potential amplifying the ra- diation induced damage. This thesis studies the combination of both techniques, as it will generate a dose enhancement, while verifying the range of the protons with the detection of the characteristic prompt gamma-rays emitted by the nanoparticles. To investigate the feasibility of performing prompt gamma-ray imaging using characteristic gamma rays from nanoparticles, a magnetite (Fe3O4) target was developed in house, consisting of a solution of nanoparticles diluted in water. The detection system consists of two different types of detectors: a CLLB scintillator and a hyper-pure germanium semiconductor. In-beam measurements were performed at the University of Birmingham (UK) and KVI- CART (Netherlands) at three different beam energies. In the current work, it is found that the CLLB detector allows for the distinction of different target compositions using the coarse energy regions in the prompt gamma-ray spectrum. The HPGe detector allows to resolve many more characteristic prompt gamma-rays with a much higher peak-to-background ratio, compared to the scintillator detector, and obtain their intensity profile. The results presented suggest that the combination of both methods provides a viable way to determine the range of the protons and confirm the location of the tumour area. The present work also indicates that measuring gamma-ray yields, using a treatment dose and nanoparticle concentration similar to the ones applied in clinic, are sufficient for localising the intensity profile of the characteristic gamma rays from the nanoparticles with a precision of a few mm, hence providing an additional tool for in-vivo range verification

Coulomb dissociation of 16O into 4He and 12C

We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(a,?)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-To-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors' active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Coulomb dissociation of ¹⁶O into ⁴He and ¹²C

We measured the Coulomb dissociation of ¹⁶O into ⁴He and ¹²C at the R³B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the ¹²C(α,γ)¹⁶O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 10⁹ ¹⁶O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into ¹²C and ⁴He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-to-charge-number ratio A/Z = 2 for ¹⁶O, ¹²C and ⁴He. Hence, radical changes of the R³B setup were necessary. All detectors had slits to allow the passage of the unreacted ¹⁶O ions, while ⁴He and ¹²C would hit the detectors’ active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision

Coulomb dissociation of ¹⁶O into ⁴He and ¹²C

Abstract We measured the Coulomb dissociation of 16O into 4He and 12C at the R3B setup in a first campaign within FAIR Phase 0 at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The goal was to improve the accuracy of the experimental data for the 12C(α,γ)16O fusion reaction and to reach lower center-ofmass energies than measured so far. The experiment required beam intensities of 109 16O ions per second at an energy of 500 MeV/nucleon. The rare case of Coulomb breakup into 12C and 4He posed another challenge: The magnetic rigidities of the particles are so close because of the same mass-to-charge-number ratio A/Z = 2 for 16O, 12C and 4He. Hence, radical changes of the R3B setup were necessary. All detectors had slits to allow the passage of the unreacted 16O ions, while 4He and 12C would hit the detectors’ active areas depending on the scattering angle and their relative energies. We developed and built detectors based on organic scintillators to track and identify the reaction products with sufficient precision.</jats:p