Range and density variations monitoring during proton therapy based on time-of-flight detection of prompt gamma radiation

Biegun, A.; Seravalli, Enrica; Lopes, P. Cambraia; Rinaldi, I.; Pinto, M.; Oxley, D.C.; Dendooven, P.; Verhaegen, Frank; Parodi, Katia; Schaart, Dennis R.; Crespo, Paulo

doi:10.1109/nssmic.2011.6152641

Cited by 3 publications

(8 citation statements)

References 4 publications

(4 reference statements)

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“…Finally, the post-processing of simulation data included TOF selection, by means of a shifting TOF window, previously described in [1 ]- [2], i.e. accepting only events incoming within a TOF window centered on the most probable TOF value ("prompt peak arrival time"), dependent on the Z coordinate.…”

Section: A Simulation Specifics and Data Analysismentioning

confidence: 99%

“…2 mm· 1 -to derive the multi-slat effective length, lei!' as in (2), and the knife-edge-slit effective (inner) diameter, deffi as in (3).…”

Section: B Analytical Performance Evaluationmentioning

confidence: 99%

“…Although first results are encouraging, prompt-gamma detection is challenging to implement in practice, mainly due to (1) the amount of statistics of the prompt signal being limited by the number of particles delivered, as determined by the treatment plan, (2) interference of background radiation from other secondary products of the irradiation -especially for higher energy proton beams [5], [7] -, and (3) the characteristic high energy of the emitted prompt photons (up to a few tens of MeV). Neutrons play a major role in the creation of the background signal, as they are difficult to stop and may give rise to secondary gamma rays when interacting in the patient, collimator, and other materials.…”

Section: Introductionmentioning

confidence: 99%

“…On the other side, the multi-slat design would possibly provide more compact devices, with a performance that is less dependent on the (varying) distance to the beam axis, as will be shown in this work. Furthermore, time-of-flight (TOF) selection has been shown to efficiently reject the background in this approach [1], [2], [4].…”

Section: Introductionmentioning

confidence: 99%

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Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Lopes

Pinto

Simoes

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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Precise monitoring of the particle range inside the body, preferably in real-time, is a primary interest in quality assurance of particle therapy. Prompt-gamma (PG) detection aims at this task, but such a system is technically challenging to implement. For mechanically collimated PG detection, neutron-induced background radiation originating in the collimator material is a major issue. We study by Monte-Carlo simulations (Geant4), the influence of different collimator designs and their geometric parameters -such as distance to source, size and septa thickness -on the correlation between transmitted PG profiles and the longitudinal depth-dose profile. The impact of background rejection by time-of-flight (TOF) is also addressed. A single-parallel-slit collimator scanned along the beam axis was primarily studied and results show that the background can be efficiently reduced by TOF discrimination. Due to reduced statistics, signal integration from neighbouring pencil-beams was further considered, accounting for typical clinical proton fluences. Furthermore, first direct-comparison results between multi-slat collimation and a knife-edge-slit collimator are presented, obtained both by simulation and analytical calculations of their geometric performances. Advantages and disadvantages of both approaches are highlighted and some design improvements are proposed. Energy thresholding was also addressed, showing that a low-energy threshold of 4 MeV increases the signal-to-background ratio in all simulation results, a factor mostly important if TOF rejection cannot be applied.

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Section: A Simulation Specifics and Data Analysismentioning

confidence: 99%

“…2 mm· 1 -to derive the multi-slat effective length, lei!' as in (2), and the knife-edge-slit effective (inner) diameter, deffi as in (3).…”

Section: B Analytical Performance Evaluationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Lopes

Pinto

Simoes

et al. 2012

2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)

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“…Dance DR (1990), Monte Carlo calculation of conversion factors for the estimation of mean glandular breast dose, Phys.Med.Biol., vol. 35…”

Section: Literatuurmentioning

confidence: 99%

Proceedings Sixth NCS Lustrum Symposium

2012

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In-beamquality assurance using induced β⁺activity in hadrontherapy: a preliminary physical requirements study using Geant4

Lestand

Montarou²,

Force³

et al. 2012

Phys. Med. Biol.

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Light and heavy ions particle therapy, mainly by means of protons and carbon ions, represents an advantageous treatment modality for deep-seated and/or radioresistant tumours. An in-beam quality assurance principle is based on the detection of secondary particles induced by nuclear fragmentations between projectile and target nuclei. Three different strategies are currently under investigation: prompt γ rays imaging, proton interaction vertex imaging and in-beam positron emission tomography. Geant4 simulations have been performed first in order to assess the accuracy of some hadronic models to reproduce experimental data. Two different kinds of data have been considered: β(+)-emitting isotopes and prompt γ-ray production rates. On the one hand simulations reproduce experimental β(+) emitting isotopes production rates to an accuracy of 24%. Moreover simulated β(+) emitting nuclei production rate as a function of depth reproduce well the peak-to-plateau ratio of experimental data. On the other hand by tuning the tolerance factor of the photon evaporation model available in Geant4, we reduce significantly prompt γ-ray production rates until a very good agreement is reached with experimental data. Then we have estimated the total amount of induced annihilation photons and prompt γ rays for a simple treatment plan of ∼1 physical Gy in a homogenous equivalent soft tissue tumour (6 cm depth, 4 cm radius and 2 cm wide). The average annihilation photons emitted during a 45 s irradiation in a 4 π solid angle are ∼2 × 10(6) annihilation photon pairs and 10(8) single prompt γ whose energy ranges from a few keV to 10 MeV.

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Range and density variations monitoring during proton therapy based on time-of-flight detection of prompt gamma radiation

Cited by 3 publications

References 4 publications

Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Proceedings Sixth NCS Lustrum Symposium

In-beamquality assurance using induced β⁺activity in hadrontherapy: a preliminary physical requirements study using Geant4

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Range and density variations monitoring during proton therapy based on time-of-flight detection of prompt gamma radiation

Cited by 3 publications

References 4 publications

Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Optimization of collimator designs for real-time proton range verification by measuring prompt gamma rays

Proceedings Sixth NCS Lustrum Symposium

In-beamquality assurance using induced β+activity in hadrontherapy: a preliminary physical requirements study using Geant4

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In-beamquality assurance using induced β⁺activity in hadrontherapy: a preliminary physical requirements study using Geant4