Experimental verification of a non-invasive method to monitor the lateral pencil beam position in an anthropomorphic phantom for carbon-ion radiotherapy

Félix-Bautista, Renato; Gehrke, Tim; Ghesquière‐Diérickx, Laura; Reimold, Marvin; Amato, Carlo; Tureček, D.; Jakůbek, J.; Ellerbrock, M.; Martišíková, M.

doi:10.1088/1361-6560/ab2ca3

Cited by 13 publications

(46 citation statements)

References 25 publications

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“…To minimize the geometrical and statistical uncertainties, we positioned the mini‐tracker on the beam axis, in contrast to our previous work (detector position at 30° with respect to the beam axis) 26 . However, the repositioning of the mini‐tracker increased the secondary‐ion fluence rate by a factor of 30, causing signal pile‐up.…”

Section: Methodsmentioning

confidence: 99%

Quality assurance method for monitoring of lateral pencil beam positions in scanned carbon‐ion radiotherapy using tracking of secondary ions

et al. 2021

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Purpose Ion beam radiotherapy offers enhances dose conformity to the tumor volume while better sparing healthy tissue compared to conventional photon radiotherapy. However, the increased dose gradient also makes it more sensitive to uncertainties. While the most important uncertainty source is the patient itself, the beam delivery is also subject to uncertainties. Most of the proton therapy centers used cyclotrons, which deliver typically a stable beam over time, allowing a continuous extraction of the beam. Carbon‐ion beam radiotherapy (CIRT) in contrast uses synchrotrons and requires a larger and energy‐dependent extrapolation of the nozzle‐measured positions to obtain the lateral beam positions in the isocenter, since the nozzle‐to‐isocenter distance is larger than for cyclotrons. Hence, the control of lateral pencil beam positions at isocenter in CIRT is more sensitive to uncertainties than in proton radiotherapy. Therefore, an independent monitoring of the actual lateral positions close to the isocenter would be very valuable and provide additional information. However, techniques capable to do so are scarce, and they are limited in precision, accuracy and effectivity. Methods The detection of secondary ions (charged nuclear fragments) has previously been exploited for the Bragg peak position of C‐ion beams. In our previous work, we investigated for the first time the feasibility of lateral position monitoring of pencil beams in CIRT. However, the reported precision and accuracy were not sufficient for a potential implementation into clinical practice. In this work, it is shown how the performance of the method is improved to the point of clinical relevance. To minimize the observed uncertainties, a mini‐tracker based on hybrid silicon pixel detectors was repositioned downstream of an anthropomorphic head phantom. However, the secondary‐ion fluence rate in the mini‐tracker rises up to 1.5 × 105 ions/s/cm2, causing strong pile‐up of secondary‐ion signals. To solve this problem, we performed hardware changes, optimized the detector settings, adjusted the setup geometry and developed new algorithms to resolve ambiguities in the track reconstruction. The performance of the method was studied on two treatment plans delivered with a realistic dose of 3 Gy (RBE) and averaged dose rate of 0.27 Gy/s at the Heidelberg Ion‐Beam Therapy Center (HIT) in Germany. The measured lateral positions were compared to reference beam positions obtained either from the beam nozzle or from a multi‐wire proportional chamber positioned at the room isocenter. Results The presented method is capable to simultaneously monitor both lateral pencil beam coordinates over the entire tumor volume during the treatment delivery, using only a 2‐cm2 mini‐tracker. The effectivity (defined as the fraction of analyzed pencil beams) was 100%. The reached precision of (0.6 to 1.5) mm and accuracy of (0.5 to 1.2) mm are in line with the clinically accepted uncertainty for QA measurements of the lateral pencil beam positions. Conclusions It was demonstra...

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Section: Methodsmentioning

confidence: 99%

Quality assurance method for monitoring of lateral pencil beam positions in scanned carbon‐ion radiotherapy using tracking of secondary ions

et al. 2021

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“…Several other methods have been proposed, such as ionoacoustic measurements [26] or mixed beams [27]. For C-ions, it is also possible to measure secondary charged particles, such as protons emitted at large angles [28,29]. A combination of different methods is under study for animal irradiators [30] and in clinical settings [31,32].…”

Section: Range Verification In Particle Therapymentioning

confidence: 99%

Radioactive Beams in Particle Therapy: Past, Present, and Future

Durante

Parodi

2020

Front. Phys.

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Heavy ion therapy can deliver high doses with high precision. However, image guidance is needed to reduce range uncertainty. Radioactive ions are potentially ideal projectiles for radiotherapy because their decay can be used to visualize the beam. Positron-emitting ions that can be visualized with PET imaging were already studied for therapy application during the pilot therapy project at the Lawrence Berkeley Laboratory, and later within the EULIMA EU project, the GSI therapy trial in Germany, MEDICIS at CERN, and at HIMAC in Japan. The results show that radioactive ion beams provide a large improvement in image quality and signal-to-noise ratio compared to stable ions. The main hindrance toward a clinical use of radioactive ions is their challenging production and the low intensities of the beams. New research projects are ongoing in Europe and Japan to assess the advantages of radioactive ion beams for therapy, to develop new detectors, and to build sources of radioactive ions for medical synchrotrons.

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“…Finally, charged fast hadrons were considered more recently for range monitoring purposes [148][149][150] in the context of ion therapy. Table 3 summarizes various measurements that are useful for MC benchmarking.…”

Section: Measurements That Were Performed In the Context Of Range Monmentioning

confidence: 99%

Challenges in Monte Carlo Simulations as Clinical and Research Tool in Particle Therapy: A Review

2020

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The use and interest in Monte Carlo (MC) techniques in the field of medical physics have been rapidly increasing in the past years. This is the case especially in particle therapy, where accurate simulations of different physics processes in complex patient geometries are crucial for a successful patient treatment and for many related research and development activities. Thanks to the detailed implementation of physics processes in any type of material, to the capability of tracking particles in 3D, and to the possibility of including the most important radiobiological effects, MC simulations have become an essential calculation tool not only for dose calculations but also for many other purposes, like the design and commissioning of novel clinical facilities, shielding and radiation protection, the commissioning of treatment planning systems, and prediction and interpretation of data for range monitoring strategies. MC simulations are starting to be more frequently used in clinical practice, especially in the form of specialized codes oriented to dose calculations that can be performed in short time. The use of general purpose MC codes is instead more devoted to research. Despite the increased use of MC simulations for patient treatments, the existing literature suggests that there are still a number of challenges to be faced in order to increase the accuracy of MC calculations for patient treatments. The goal of this review is to discuss some of these remaining challenges. Undoubtedly, it is a work for which a multidisciplinary approach is required. Here, we try to identify some of the aspects where the community involved in applied nuclear physics, radiation biophysics, and computing development can contribute to find solutions. We have selected four specific challenges: i) the development of models in MC to describe nuclear physics interactions, ii) modeling of radiobiological processes in MC simulations, iii) developments of MC-based treatment planning tools, and iv) developments of fast MC codes. For each of them, we describe the underlying problems, present selected examples of proposed solutions, and try to give recommendations for future research.

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Experimental verification of a non-invasive method to monitor the lateral pencil beam position in an anthropomorphic phantom for carbon-ion radiotherapy

Cited by 13 publications

References 25 publications

Quality assurance method for monitoring of lateral pencil beam positions in scanned carbon‐ion radiotherapy using tracking of secondary ions

Quality assurance method for monitoring of lateral pencil beam positions in scanned carbon‐ion radiotherapy using tracking of secondary ions

Radioactive Beams in Particle Therapy: Past, Present, and Future

Challenges in Monte Carlo Simulations as Clinical and Research Tool in Particle Therapy: A Review

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