Ultra-fast pencil beam scanning proton therapy for locally advanced non-small-cell lung cancers: Field delivery within a single breath-hold

Maradia, Vivek; Water, Steven van de; Meer, D.; Weber, Damien Charles; Lomax, Anthony; Psoroulas, S.

doi:10.1016/j.radonc.2022.06.018

Cited by 15 publications

(17 citation statements)

References 30 publications

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“…As this approach allows for transport of maximum acceptable emittance in both planes, this method substantially increases the low energy beam transmission through the beamline, while achieving gantry angle independent beam sizes at the isocenter. The obtained higher intensities (dose rates) could reduce treatment delivery times to aid motion mitigation techniques such as breath-hold, gating, and rescanning [15]. In addition, shorter treatment delivery times may increase patient throughput, lowering the cost of proton therapy treatment.…”

Section: Discussionmentioning

confidence: 99%

A novel method of emittance matching to increase beam transmission for cyclotron-based proton therapy facilities: simulation study

Maradia

Meer

Weber

et al. 2023

J. Phys.: Conf. Ser.

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In proton therapy, high dose rates can reduce treatment delivery times, allowing for efficient mitigation of tumor motion and increased patient throughput. With cyclotrons however, high dose rates are difficult to achieve for low-energies as, typically, the emittance after the degrader is matched in both transversal planes using circular collimators, which does not provide an optimal matching to the acceptance of the following beamline. Transmission can however be substantially improved by transporting maximum acceptable emittances in both orthogonal planes, but at the cost of gantry angle-dependent beam shapes at isocenter. Here we demonstrate that equal emittances in both planes can be recovered at the gantry entrance using a thin scattering foil, thus ensuring gantry angle-independent beam shapes at the isocenter. We demonstrate in simulation that low-energy beam transmission can be increased by a factor of 3 using this approach compared to the currently used beam optics, whilst gantry angle-independent beam shapes are preserved. We expect that this universal approach could also bring a similar transmission improvement in other cyclotron-based proton therapy facilities.

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Section: Discussionmentioning

confidence: 99%

A novel method of emittance matching to increase beam transmission for cyclotron-based proton therapy facilities: simulation study

Maradia

Meer

Weber

et al. 2023

J. Phys.: Conf. Ser.

Self Cite

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show abstract

“…The obtained higher intensities (dose rates) could reduce treatment delivery times to aid motion mitigation techniques such as breathhold, gating and rescanning. In particular, our work could contribute to reducing delivery times such as to enable single fields to be delivered within a single breath-hold [9]. In addition to improvement in patient comfort, the resulting shorter treatment delivery times could also be of help to increase patient throughput.…”

Section: Discussionmentioning

confidence: 99%

“…For all these techniques, it is also desirable to have shorter treatment delivery times. Whilst shorter treatment delivery times would anyway be welcome in PBS proton therapy from a cost-effectiveness point of view, they could also substantially ease motion mitigation if a single PBS field could be delivered within a single breath-hold [9]. In PBS proton therapy, treatment delivery time depends on beam-on time and on the dead time (time required to change energy layers and/or lateral position).…”

Section: Introductionmentioning

confidence: 99%

Application of a scattering foil to increase beam transmission for cyclotron based proton therapy facilities

et al. 2022

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In proton therapy, high dose rates can reduce treatment delivery times, allowing for efficient mitigation of tumor motion, as well as increased treatment efficiency and patient throughput. In cyclotron-based facilities, however, high dose rates are difficult to achieve at low-energies. In current facilities, the emittance after the degrader is matched in both transversal planes using circular collimators; this does not provide an optimal matching to the acceptance of the following beamline. However, transmission can be substantially improved by transporting maximum acceptable emittances in the X and Y planes, but at the cost of an elliptical beam shape at the gantry entrance, leading to gantry angle-dependent beam shapes at the isocenter. Here we demonstrate that equal emittances in both planes can be recovered at the gantry entrance using a thin scattering foil, thus ensuring gantry angle-independent beam shape at the isocenter. Using modified beam optics and thin scattering foil placed in the beamline, we demonstrate experimentally that low-energy beam transmission can be increased by a factor of three compared to the currently used beam optics, whilst preserving gantry angle-independent beam shapes, at the cost of a large beam size. We expect that this approach could also bring a similar transmission improvement in other cyclotron-based proton therapy facilities.

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“…It could reduce the difficulties to treat moving tumors and could enable the treatment with certain motion mitigation techniques efficiently and effectively. High intensity could allow to deliver a field within a single breath‐hold 19,20 . It could also help to reach the dose rates required for FLASH irradiations.…”

Section: Discussionmentioning

confidence: 99%

Increase of the transmission and emittance acceptance through a cyclotron‐based proton therapy gantry

et al. 2022

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Purpose In proton therapy, the gantry, as the final part of the beamline, has a major effect on beam intensity and beam size at the isocenter. Most of the conventional beam optics of cyclotron‐based proton gantries have been designed with an imaging factor between 1 and 2 from the coupling point (CP) at the gantry entrance to the isocenter (patient location) meaning that to achieve a clinically desirable (small) beam size at isocenter, a small beam size is also required at the CP. Here we will show that such imaging factors are limiting the emittance which can be transported through the gantry. We, therefore, propose the use of large beam size and low divergence beam at the CP along with an imaging factor of 0.5 (2:1) in a new design of gantry beam optics to achieve substantial improvements in transmission and thus increase beam intensity at the isocenter. Methods The beam optics of our gantry have been re‐designed to transport higher emittance without the need of any mechanical modifications to the gantry beamline. The beam optics has been designed using TRANSPORT, with the resulting transmissions being calculated using Monte Carlo simulations (BDSIM code). Finally, the new beam optics have been tested with measurements performed on our Gantry 2 at PSI. Results With the new beam optics, we could maximize transmission through the gantry for a fixed emittance value. Additionally, we could transport almost four times higher emittance through the gantry compared to conventional optics, whilst achieving good transmissions through the gantry (>50%) with no increased losses in the gantry. As such, the overall transmission (cyclotron to isocenter) can be increased by almost a factor of 6 for low energies. Additionally, the point‐to‐point imaging inherent to the optics allows adjustment of the beam size at the isocenter by simply changing the beam size at the CP. Conclusion We have developed a new gantry beam optics which, by selecting a large beam size and low divergence at the gantry entrance and using an imaging factor of 0.5 (2:1), increases the emittance acceptance of the gantry, leading to a substantial increase in beam intensity at low energies. We expect that this approach could easily be adapted for most types of existing gantries.

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Ultra-fast pencil beam scanning proton therapy for locally advanced non-small-cell lung cancers: Field delivery within a single breath-hold

Cited by 15 publications

References 30 publications

A novel method of emittance matching to increase beam transmission for cyclotron-based proton therapy facilities: simulation study

A novel method of emittance matching to increase beam transmission for cyclotron-based proton therapy facilities: simulation study

Application of a scattering foil to increase beam transmission for cyclotron based proton therapy facilities

Increase of the transmission and emittance acceptance through a cyclotron‐based proton therapy gantry

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