Monte Carlo simulations on performance of double-scattering Compton camera

Park, J. H.; Seo, Hee; Kim, Y. S.; Kim, C. H.; Lee, J. H.; Lee, C. S.; Kim, S. M.; Lee, Jae Sung

doi:10.1088/1748-0221/7/01/c01009

Cited by 5 publications

(3 citation statements)

References 13 publications

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“…Different approaches for the detection of these prompt gamma rays are investigated worldwide, relying on the measurement of the spatial (Prompt Gamma Imaging PGI), energy (Prompt Gamma Spectroscopy PGS (Verburg and Seco 2014)), or the temporal distribution (Prompt Gamma Timing PGT (Golnik et al 2014)) of the prompt gammas. For the spatial measurement of the gamma distribution, a Compton Camera can be used, which is based on electronic collimation of the photons reaching the detector (Frandes et al 2010, Kormoll et al 2011, Richard et al 2011, Robertson et al 2011, Park et al 2012, Trovato et al 2013, Hueso-González et al 2014, Krimmer et al 2015, Thirolf et al 2014. Another possibility is the passive collimation of the gamma rays by means of a mechanical collimator made from, e.g.…”

Section: Introductionmentioning

confidence: 99%

Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

Priegnitz¹,

Helmbrecht²,

Janssens³

et al. 2015

Phys. Med. Biol.

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Proton and ion beam therapies become increasingly relevant in radiation therapy. To fully exploit the potential of this irradiation technique and to achieve maximum target volume conformality, the verification of particle ranges is highly desirable. Many research activities focus on the measurement of the spatial distributions of prompt gamma rays emitted during irradiation. A passively collimating knife-edge slit camera is a promising option to perform such measurements. In former publications, the feasibility of accurate detection of proton range shifts in homogeneous targets could be shown with such a camera. We present slit camera measurements of prompt gamma depth profiles in inhomogeneous targets. From real treatment plans and their underlying CTs, representative beam paths are selected and assembled as one-dimensional inhomogeneous targets built from tissue equivalent materials. These phantoms have been irradiated with monoenergetic proton pencil beams. The accuracy of range deviation estimation as well as the detectability of range shifts is investigated in different scenarios. In most cases, range deviations can be detected within less than 2 mm. In close vicinity to low-density regions, range detection is challenging. In particular, a minimum beam penetration depth of 7 mm beyond a cavity is required for reliable detection of a cavity filling with the present setup. Dedicated data post-processing methods may be capable of overcoming this limitation.

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Section: Introductionmentioning

confidence: 99%

Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

Priegnitz¹,

Helmbrecht²,

Janssens³

et al. 2015

Phys. Med. Biol.

View full text Add to dashboard Cite

show abstract

“…Measurement of the spatial prompt γ-ray distribution requires collimation of the photons reaching the detector. This collimation can be realized electronically like in a Compton camera (Frandes et al 2010, Kormoll et al 2011, Richard et al 2011, Park et al 2012, Llosá et al 2013, Hueso-González et al 2014, Thirolf et al 2014, Polf et al 2015. Alternatively, γ-rays can be collimated mechanically for restricting the direction of their impact on the detector.…”

Section: Introductionmentioning

confidence: 99%

Towards clinical application: prompt gamma imaging of passively scattered proton fields with a knife-edge slit camera

et al. 2016

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Prompt γ-ray imaging with a knife-edge shaped slit camera provides the possibility of verifying proton beam range in tumor therapy. Dedicated experiments regarding the characterization of the camera system have been performed previously. Now, we aim at implementing the prototype into clinical application of monitoring patient treatments. Focused on this goal of translation into clinical operation, we systematically addressed remaining challenges and questions. We developed a robust energy calibration routine and corresponding quality assurance protocols. Furthermore, with dedicated experiments, we determined the positioning precision of the system to 1.1 mm (2σ). For the first time, we demonstrated the application of the slit camera, which was intentionally developed for pencil beam scanning, to double scattered proton beams. Systematic experiments with increasing complexity were performed. It was possible to visualize proton range shifts of 2-5 mm with the camera system in phantom experiments in passive scattered fields. Moreover, prompt γ-ray profiles for single iso-energy layers were acquired by synchronizing time resolved measurements to the rotation of the range modulator wheel of the treatment system. Thus, a mapping of the acquired profiles to different anatomical regions along the beam path is feasible and additional information on the source of potential range shifts can be obtained. With the work presented here, we show that an application of the slit camera in clinical treatments is possible and of potential benefit.

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“…Spatial measurement of the prompt gamma rays requires collimation of the photons that reach the detector. This collimation can be electronic as in a Compton Camera (Frandes et al 2010, Kormoll et al 2011, Richard et al 2011, Robertson et al 2011, Park et al 2012, Trovato et al 2013, Hueso-González et al 2014, Thirolf et al 2014. Another possibility is the passive collimation with a mechanical collimator made from e.g.…”

Section: Introductionmentioning

confidence: 99%

Detection of mixed-range proton pencil beams with a prompt gamma slit camera

et al. 2016

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With increasing availability of proton and particle therapy centers for tumor treatment, the need for in vivo range verification methods comes more into the focus. Imaging of prompt gamma rays emitted during the treatment is one of the possibilities currently under investigation. A knife-edge shaped slit camera was recently proposed for this task and measurements proved the feasibility of range deviation detection in homogeneous and inhomogeneous targets. In the present paper, we concentrate on laterally inhomogeneous materials, which lead to range mixing situations when crossed by one pencil beam: different sections of the beam have different ranges. We chose exemplative cases from clinical irradiation and assembled idealized tissue equivalent targets. One-dimensional emission profiles were obtained by measuring the prompt gamma emission with the slit camera. It could be shown that the resulting range deviations can be detected by evaluation of the measured data with a previously developed range deviation detection algorithm. The retrieved value, however, strongly depends on the target composition, and is not necessarily in direct relation to the ranges of both parts of the beam. By combining the range deviation detection with an analysis of the slope of the distal edge of the measured prompt gamma profile, the origin of the detected range deviation, i.e. the mixed range of the beam, is also identified. It could be demonstrated that range mixed prompt gamma profiles exhibit less steep distal slopes than profiles from beams traversing laterally homogeneous material. For future application of the slit camera to patient irradiation with double scattered proton beams, situations similar to the range mixing cases are present and results could possibly apply.

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Monte Carlo simulations on performance of double-scattering Compton camera

Cited by 5 publications

References 13 publications

Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

Measurement of prompt gamma profiles in inhomogeneous targets with a knife-edge slit camera during proton irradiation

Towards clinical application: prompt gamma imaging of passively scattered proton fields with a knife-edge slit camera

Detection of mixed-range proton pencil beams with a prompt gamma slit camera

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