Evaluation of Spatial Resolution for Heavy Ion CT System Based on the Measurement of Residual Range Distribution With HIMAC

Muraishi, H.; Nishimura, Katsuyuki; Abe, Shinji; Satoh, Hitoshi; Hara, Satoshi; Hara, Hidetake; Takahashi, Yusuke; Mogaki, Tatsuya; Kawai, R.; Yokoyama, Kota; Yasuda, N.; Tomida, Tetsuya; Ohno, Yumiko; Kanai, Tatsuaki

doi:10.1109/tns.2009.2023520

Cited by 22 publications

(19 citation statements)

References 27 publications

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“…Passive field + pixel detector (Lower left panel in Fig. 1) In a treatment facility with passive double scattering beam delivery, it has been proposed to irradiate the patient with an extended field and capture the protons with a position sensitive single plane detector placed behind the patient (Zygmanski et al 2000, Lu 2008, Muraishi et al 2009, Seco & Depauw 2011, Testa et al 2013. The initial beam energy is modulated, e.g., with a spinning wheel with decreasing material thickness, while each detector pixel records the signal over time.…”

Section: Set-upsmentioning

confidence: 99%

A comprehensive theoretical comparison of proton imaging set-ups in terms of spatial resolution

et al. 2018

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We present a comprehensive analytical comparison of four types of proton imaging set-ups and, to this end, develop a mathematical framework to calculate the width of the uncertainty envelope around the most likely proton path depending on set-up geometry, detector properties, and proton beam parameters. As a figure of merit for the spatial resolution achievable with each set-up, we use the frequency [Formula: see text] at which the modular transfer function of a density step decreases below 10%. We verify the analytical results with Monte Carlo simulations. We find that set-ups which track the angle and position of individual protons in front of and behind the phantom would yield an average spatial resolution of 0.3-0.35 lp mm assuming realistic geometric parameters (i.e. 30-40 cm distance between detector and phantom, 15-20 cm phantom thickness). For set-ups combining pencil beam scanning with either a position sensitive detector, e.g. an x-ray flat panel, or with a position insensitive detector, e.g. a range telescope, we find an average spatial resolution of about 0.1 lp mm for an 8 mm FWHM beam spot size. The pixel information improves the spatial resolution by less than 10%. In both set-up types, performance can be significantly improved by reducing the pencil beam size down to 2 mm FWHM. In this case, the achievable spatial resolution reaches about 0.25 lp mm. Our results show that imaging set-ups combining double scattering with a pixel detector can provide sufficient spatial resolution only under very stringent conditions and are not ideally suited for computed tomography applications. We further propose a region-of-interest method for set-ups with a pixel detector to filter out protons which have undergone nuclear reactions and discuss the impact of tracker detector uncertainties on the most likely path.

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Section: Set-upsmentioning

confidence: 99%

A comprehensive theoretical comparison of proton imaging set-ups in terms of spatial resolution

et al. 2018

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“…It can be seen by the fact that the 2 mm wide steps could be clearly resolved for the images with tracking, while they could not be separately perceived in the images without tracking. The tracking of the ions is of importance, as the MCS of the helium ions — although less pronounced than for protons — plays a not negligible role for helium‐beam radiography . This is in contrast to carbon ion imaging, where many detection systems were developed without tracking capabilities based on the assumption that the image blurring due MCS of carbon ions is sufficiently small …”

Section: Discussion and Outlookmentioning

confidence: 99%

“…The tracking of the ions is of importance, as the MCS of the helium ionsalthough less pronounced than for protonsplays a not negligible role for helium-beam radiography. 18,30 This is in contrast to carbon ion imaging, where many detection systems were developed without tracking capabilities based on the assumption that the image blurring due MCS of carbon ions is sufficiently small. 19,20,58 The presented detection system that allows helium ion tracking behind the object leads to good spatial resolutions (MTF 10% > 1.15 lp mm À1 ) in the case, where the feature of interest is located at the rear of the object.…”

Section: Discussion and Outlookmentioning

confidence: 99%

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Proof of principle of helium‐beam radiography using silicon pixel detectors for energy deposition measurement, identification, and tracking of single ions

et al. 2018

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“…As such, there has been a recent movement toward using only a single detector positioned beyond the patient. A variety of technologies have been explored, including fluorescent screens coupled to CCD cameras, [31][32][33] commercial flat-panel detectors, 34 and complementary metal oxide semiconductor active pixel sensors (CMOS APS). 3,17,35 The measurement of dose offers a simple approach to proton radiography.…”

Section: Introductionmentioning

confidence: 99%

Dose ratio proton radiography using the proximal side of the Bragg peak

et al. 2015

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Purpose: In recent years, there has been a movement toward single-detector proton radiography, due to its potential ease of implementation within the clinical environment. One such single-detector technique is the dose ratio method in which the dose maps from two pristine Bragg peaks are recorded beyond the patient. To date, this has only been investigated on the distal side of the lower energy Bragg peak, due to the sharp falloff. The authors investigate the limits and applicability of the dose ratio method on the proximal side of the lower energy Bragg peak, which has the potential to allow a much wider range of water-equivalent thicknesses (WET) to be imaged. Comparisons are made with the use of the distal side of the Bragg peak. Methods: Using the analytical approximation for the Bragg peak, the authors generated theoretical dose ratio curves for a range of energy pairs, and then determined how an uncertainty in the dose ratio would translate to a spread in the WET estimate. By defining this spread as the accuracy one could achieve in the WET estimate, the authors were able to generate lookup graphs of the range on the proximal side of the Bragg peak that one could reliably use. These were dependent on the energy pair, noise level in the dose ratio image and the required accuracy in the WET. Using these lookup graphs, the authors investigated the applicability of the technique for a range of patient treatment sites. The authors validated the theoretical approach with experimental measurements using a complementary metal oxide semiconductor active pixel sensor (CMOS APS), by imaging a small sapphire sphere in a high energy proton beam. Results: Provided the noise level in the dose ratio image was 1% or less, a larger spread of WETs could be imaged using the proximal side of the Bragg peak (max 5.31 cm) compared to the distal side (max 2.42 cm). In simulation, it was found that, for a pediatric brain, it is possible to use the technique to image a region with a square field equivalent size of 7.6 cm 2 , for a required accuracy in the WET of 3 mm and a 1% noise level in the dose ratio image. The technique showed limited applicability for other patient sites. The CMOS APS demonstrated a good accuracy, with a root-mean-square-error of 1.6 mm WET. The noise in the measured images was found to be σ = 1.2% (standard deviation) and theoretical predictions with a 1.96σ noise level showed good agreement with the measured errors. Conclusions: After validating the theoretical approach with measurements, the authors have shown that the use of the proximal side of the Bragg peak when performing dose ratio imaging is feasible, and allows for a wider dynamic range than when using the distal side. The dynamic range available increases as the demand on the accuracy of the WET decreases. The technique can only be applied to clinical sites with small maximum WETs such as for pediatric brains. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License...

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Evaluation of Spatial Resolution for Heavy Ion CT System Based on the Measurement of Residual Range Distribution With HIMAC

Cited by 22 publications

References 27 publications

A comprehensive theoretical comparison of proton imaging set-ups in terms of spatial resolution

A comprehensive theoretical comparison of proton imaging set-ups in terms of spatial resolution

Proof of principle of helium‐beam radiography using silicon pixel detectors for energy deposition measurement, identification, and tracking of single ions

Dose ratio proton radiography using the proximal side of the Bragg peak

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