Review of medical radiography and tomography with proton beams

Johnson, R. P.

doi:10.1088/1361-6633/aa8b1d

Cited by 132 publications

(140 citation statements)

References 109 publications

Supporting

Mentioning

139

Contrasting

Unclassified

Order By: Relevance

“…On the one hand, list-mode proton radiography tracks protons individually. 9 Both their energy loss and their trajectories are measured, which requires complex hardware to be placed before and after the patient. 10 On the other hand, the integrated mode proton radiography integrates the contribution of every proton during the irradiation time of a pencil beam shot.…”

Section: Introductionmentioning

confidence: 99%

Sparse deconvolution of proton radiography data to estimate water equivalent thickness maps

2019

View full text Add to dashboard Cite

Purpose In proton therapy, the conversion of the planning computed tomography (CT) into proton stopping powers is tainted by uncertainties which may jeopardize dose conformity. Proton radiography provides a direct information on the energy reduction of protons in the patient. However, it is currently limited by the degradation (“blurring”) of the one‐dimensional depth‐dose deposition profiles which constitute the pixels. Methods An iterative algorithm is implemented to extract high‐resolution water equivalent thickness (WET) maps from the measurements of depth‐dose profiles acquired with a multilayer ionization chamber. The method relies on the assumption that those curves are a function of the WET, which can benefit from a sparse representation. Results When used without relying on any prior knowledge derived from the planning CT, the method already outperforms the published one in terms of accuracy. We also propose a variant which integrates the planning CT in a robust fashion to further improve the deconvolution result and reach an accuracy of 1.5 mm on the estimated WET. The methods are applied to both synthetic data and actual proton radiography acquisitions on phantoms. Conclusions Besides the increase in accuracy achieved in the estimation of WET maps from proton radiography data, we demonstrate that the proposed deconvolution algorithm is also more robust with respect to confounding factors such as residual setup errors or changes in the anatomy. Therefore, proton radiography using a range probe provides both the required accuracy to assess and reduce range uncertainty in proton therapy and the simplicity of integrated‐mode proton radiography.

show abstract

Section: Introductionmentioning

confidence: 99%

Sparse deconvolution of proton radiography data to estimate water equivalent thickness maps

2019

View full text Add to dashboard Cite

show abstract

“…Because of the

{false(β^{2} (z) p^{2} (z) false)}^{- 1}

dependence in the integral, increasing the initial energy of the ions has the effect of decreasing the lateral displacement of ions in the phantom. Therefore, an increase in SR is expected with increasing beam energies . This effect was experimentally and systematically investigated in this study for the first time.…”

Section: Introductionmentioning

confidence: 81%

A technique for spatial resolution improvement in helium‐beam radiography

2020

View full text Add to dashboard Cite

Purpose: Ion-beam radiography exhibits a significantly lower spatial resolution (SR) compared to xray radiography. This is mostly due the multiple Coulomb scattering (MCS) that the ions undergo in the imaged object. In this work, a novel technique to improve the spatial resolution in helium-beam radiography was developed. Increasing helium-beam energies were exploited in order to decrease the MCS, and therefore increase the SR. Methods: The experimental investigation was carried out with a dedicated ion-tracking imaging system fully composed of thin, pixelated silicon detectors (Timepix). Four helium beams with increasing energies (from 168.8 to 220.5 MeV/u) were used to image a homogeneous 160 mm PMMA phantom with a 2 mm air gap at middle depth. An energy degrader (ED) was placed between the rear tracking system and the energy-deposition detector to compensate for the longer range associated with more energetic ions. The SR was measured for each beam energy. To take into account the overall impact on the image quality, the contrast-to-noise ratio (CNR), the single-ion water equivalent thickness (WET) precision and the absorbed dose in the phantom were also evaluated as a function of the initial beam energy. FLUKA Monte Carlo simulations were used to support the conceptual design of the experimental setup and for dose estimation. Results: In the investigated energy interval, a total SR increase by around 30% was measured with increasing beam energy, reaching a maximum value of 0.69 lp/mm. For radiographs generated with 350 lGy of absorbed dose and 220 lm pixel size, a CNR decrease of 32% was found as the beam energy increases. For 1 mm pixel size, the CNR decreases only by 22%. The CNR of the images was always above 6. The single-ion WET precision was found to be in a range between 1.2% and 1.5%. Conclusions: We have experimentally shown and quantified the possibility of improving SR in helium-beam radiography by using increasing beam energies in combination with an ED. A significant SR increase was measured with an acceptable decrease of CNR. Furthermore, we have shown that an ED can be a valuable tool to exploit increasing beam energies to generate energy-deposition radiographs.

show abstract

“…Proton radiography and proton CT have already been investigated a long time ago (West & Sherwood 1972, Koehler 1968, Steward & Koehler 1973, Takada et al 1988) and more recently been brought up in the context of proton beam therapy (Schneider & Pedroni 1995, Schulte et al 2004. In analogy to X-ray based transmission imaging, protons are shot through the patient and an image is formed based on the residual energy or residual range measured by a suitable detector positioned behind the patient (Parodi 2014, Poludniowski et al 2015, Johnson 2018. A full tomographic scan directly provides a volumetric RSP map of the patient and therefore bypasses any conversion.…”

Section: Methodsmentioning

confidence: 99%

Regularised patient-specific stopping power calibration for proton therapy planning based on proton radiographic images

et al. 2019

View full text Add to dashboard Cite

HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

show abstract

Review of medical radiography and tomography with proton beams

Cited by 132 publications

References 109 publications

Sparse deconvolution of proton radiography data to estimate water equivalent thickness maps

Sparse deconvolution of proton radiography data to estimate water equivalent thickness maps

A technique for spatial resolution improvement in helium‐beam radiography

Regularised patient-specific stopping power calibration for proton therapy planning based on proton radiographic images

Contact Info

Product

Resources

About