Toward a new treatment planning approach accounting for <i>in vivo</i> proton range verification

Tian, Liheng; Landry, Guillaume; Dedes, Georgios; Kamp, Florian; Pinto, M.; Niepel, Katharina; Belka, Claus; Parodi, Katia

doi:10.1088/1361-6560/aae749

Cited by 19 publications

(36 citation statements)

References 31 publications

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“…To make maximum use of these spots and increase the SPIRE amplitude, the intensity modulated proton therapy (IMPT) technique 39 may be suitable in which a high dose is delivered to the key spots that are used for the SPIRE measurement. Note that this idea of "key spot" was already proposed in Tian et al by the name of "SubPencilBeam" in the context of prompt gamma imaging 40 . The dose homogeneity is then recovered by suppressing the beam intensity delivered to the surrounding spots.…”

Section: Discussionmentioning

confidence: 96%

On-line range verification for proton beam therapy using spherical ionoacoustic waves with resonant frequency

Takayanagi

Uesaka

Nakamura

et al. 2020

Sci Rep

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In contrast to conventional X-ray therapy, proton beam therapy (PBT) can confine radiation doses to tumours because of the presence of the Bragg peak. However, the precision of the treatment is currently limited by the uncertainty in the beam range. Recently, a unique range verification methodology has been proposed based on simulation studies that exploit spherical ionoacoustic waves with resonant frequency (SPIREs). SPIREs are emitted from spherical gold markers in tumours initially introduced for accurate patient positioning when the proton beam is injected. These waves have a remarkable property: their amplitude is linearly correlated with the residual beam range at the marker position. Here, we present proof-of-principle experiments using short-pulsed proton beams at the clinical dose to demonstrate the feasibility of using SPIREs for beam-range verification with submillimetre accuracy. These results should substantially contribute to reducing the range uncertainty in future PBT applications.

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Section: Discussionmentioning

confidence: 96%

On-line range verification for proton beam therapy using spherical ionoacoustic waves with resonant frequency

Takayanagi

Uesaka

Nakamura

et al. 2020

Sci Rep

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“…Finally, assuming pencil beam scanning, the number of sensors needs to be large enough to allow for optimal field-of-view in at least a few favorable pencil beam positions of the treatment plan, ideally corresponding to those of highest weights. Alternatively, the treatment plan could be optimized in order to deliver higher dose to favorable spots, allowing for optimal acquisition conditions, as previously proposed by Tian et al for prompt gamma imaging (Tian et al 2018).…”

Section: Ideal Sensor Arrangement For Accurate Ionoacoustics-based Ra...mentioning

confidence: 99%

Investigating the accuracy of co-registered ionoacoustic and ultrasound images in pulsed proton beams

et al. 2021

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The sharp spatial and temporal dose gradients of pulsed ion beams result in an acoustic emission (ionoacoustics), which can be used to reconstruct the dose distribution from measurements at different positions. The accuracy of range verification from ionoacoustic images measured with an ultrasound linear array configuration is investigated both theoretically and experimentally for monoenergetic proton beams at energies relevant for pre-clinical studies (20 and 22 MeV). The influence of the linear sensor array arrangement (length up to 4 cm and number of elements from 5 to 200) and medium properties on the range estimation accuracy are assessed using time-reversal reconstruction. We show that for an ideal homogeneous case, the ionoacoustic images enable a range verification with a relative error lower than 0.1%, however, with limited lateral dose accuracy. Similar results were obtained experimentally by irradiating a water phantom and taking into account the spatial impulse response (geometry) of the acoustic detector during the reconstruction of pressures obtained by moving laterally a single-element transducer to mimic a linear array configuration. Finally, co-registered ionoacoustic and ultrasound images were investigated using silicone inserts immersed in the water phantom across the proton beam axis. By accounting for the sensor response and speed of sound variations (deduced from co-registration with ultrasound images) the accuracy is improved to a few tens of micrometers (relative error less than to 0.5%), confirming the promise of ongoing developments for ionoacoustic range verification in pre-clinical and clinical proton therapy applications.

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“…Therefore, we will have to investigate whether the SNR could be kept high in the conventional regimen. Nevertheless, the beam intensity of this study could still be used in clinical settings if we use the intensity‐modulated proton therapy and give high doses to the subset of spots specially selected for the range verification 30,45 . Despite the large SNR in the low‐frequency regime, the detector sensitivity was insufficient to detect the beam range with a single pulse in the SPIRE measurement, and the simultaneous measurement of the γ‐wave and SPIRE was not achieved.…”

Section: Discussionmentioning

confidence: 98%

“…Nevertheless, the beam intensity of this study could still be used in clinical settings if we use the intensity-modulated proton therapy and give high doses to the subset of spots specially selected for the range verification. 30,45 Despite the large SNR in the low-frequency regime, the detector sensitivity was insufficient to detect the beam range with a single pulse in the SPIRE measurement, and the simultaneous measurement of the γ-wave and SPIRE was not achieved. If this was achieved in a clinical setting, even if the propagation of either one of the IA waves was obstructed by the shadowed area (such as bony structures), the other one could be used for range detection.…”

Section: Discussionmentioning

confidence: 99%

Ionoacoustic application of an optical hydrophone to detect proton beam range in water

et al. 2023

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Background Proton range uncertainty has been the main factor limiting the ability of proton therapy to concentrate doses to tumors to their full potential. Ionoacoustic (IA) range verification is an approach to reducing this uncertainty by detecting thermoacoustic waves emitted from an irradiated volume immediately following a pulsed proton beam delivery; however, the signal weakness has been an obstacle to its clinical application. To increase the signal‐to‐noise ratio (SNR) with the conventional piezoelectric hydrophone (PH), the detector‐sensitive volume needs to be large, but it could narrow the range of available beam angles and disturb real‐time images obtained during beam delivery. Purpose To prevent this issue, we investigated a millimeter‐sized optical hydrophone (OH) that exploits the laser interferometric principle. For two types of IA waves [γ‐wave emitted from the Bragg peak (BP) and a spherical IA wave with resonant frequency (SPIRE) emitted from the gold fiducial marker (GM)], comparisons were made with PH in terms of waveforms, SNR, range detection accuracy, and signal intensity robustness against the small detector misalignment, particularly for SPIRE. Methods A 100‐MeV proton beam with a 27 ns pulse width and 4 mm beam size was produced using a fixed‐field alternating gradient accelerator and was irradiated to the water phantom. The GM was set on the beam's central axis. Acrylic plates of various thicknesses, up to 12 mm, were set in front of the phantoms to shift the proton range. OH was set distal and lateral to the beam, and the range was estimated using the time‐of‐flight method for γ‐wave and by comparing with the calibration data (SPIRE intensity versus the distance between the GM and BP) derived from an IA wave transport simulation for SPIRE. The BP dose per pulse was 0.5–0.6 Gy. To measure the variation in SPIRE amplitude against the hydrophone misalignment, the hydrophone was shifted by ± 2 mm at a maximum in lateral directions. Results Despite its small size, OH could detect γ‐wave with a higher SNR than the conventional PH (diameter, 29 mm), and a single measurement was sufficient to detect the beam range with a submillimeter accuracy in water. In the SPIRE measurement, OH was far more robust against the detector misalignment than the focused PH (FPH) used in our previous study [5%/mm (OH) versus 80%/mm (FPH)], and the correlation between the measured SPIRE intensity and the distance between the GM and BP agreed well with the simulation results. However, the OH sensitivity was lower than the FPH sensitivity, and about 5.6‐Gy dose was required to decrease the intensity variation among measurements to less than 10%. Conclusion The miniature OH was found to detect weak IA signals produced by proton beams with a BP dose used in hypofractionated regimens. The OH sensitivity improvement at the MHz regime is worth exploring as the next step.

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Toward a new treatment planning approach accounting for in vivo proton range verification

Cited by 19 publications

References 31 publications

On-line range verification for proton beam therapy using spherical ionoacoustic waves with resonant frequency

On-line range verification for proton beam therapy using spherical ionoacoustic waves with resonant frequency

Investigating the accuracy of co-registered ionoacoustic and ultrasound images in pulsed proton beams

Ionoacoustic application of an optical hydrophone to detect proton beam range in water

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