Deep learning-based in vivo dose verification from proton-induced secondary-electron-bremsstrahlung images with various count level

Yabe, Takuya; Yamaguchi, Mitsutaka; Liu, Chih-Chieh; Toshito, T.; Kawachi, Naoki; Yamamoto, Seiichi

doi:10.1016/j.ejmp.2022.05.013

Cited by 13 publications

(12 citation statements)

References 34 publications

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“…This was because the images of prompt x-rays did not have a Bragg peak at the end of the beams, and thus the error was slightly larger in estimating the ranges. However, by using deep learning approaches, the distribution will be changed to dose distributions [41,42], possibly improving the accuracy of range estimation as well as estimating the dose distribution from the prompt x-ray images. Improving the accuracy in range estimation from the measured prompt x-ray images using such as deep learning or other methods is our future work to proceed.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, since the measured luminescence images represent the dose distribution, these image pairs of luminescence and prompt x-rays will be used for training in the deep learning of neural networks aimed at predicting dose distributions from prompt x-ray images [41,42], even for clinically used therapy beams. These are also our future work to proceed.…”

Section: Discussionmentioning

confidence: 99%

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Simultaneous imaging of luminescence and prompt x-rays during irradiation with spot-scanning proton beams at clinical dose level

Yamamoto¹,

Yamashita²,

Kobashi³

et al. 2023

Biomed. Phys. Eng. Express

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Prompt x-ray imaging is a promising method for observing the beam shape from outside a subject. However, its distribution is different from dose distribution, and thus a comparison with the dose is required. Meanwhile, luminescence imaging of water is a possible method for imaging the dose distribution. Consequently, we performed simultaneous imaging of luminescence and prompt x-rays during irradiation by proton beams to compare the distributions between these two different imaging methods. Optical imaging of water was conducted with spot-scanning proton beams at clinical dose level during irradiation to a fluorescein (FS) water phantom set in a black box. Prompt x-ray imaging was also conducted simultaneously from outside the black box using a developed x-ray camera during proton beam irradiation to the phantom. We measured images of the luminescence of FS water and prompt x-rays for various types of proton beams, including pencil beams, spread-out Bragg peak (SOBP) beams, and clinically used therapy beams. After the imaging, ranges were estimated from FS water and prompt x-rays and compared with those calculated with a treatment planning system (TPS). We could measure the prompt x-ray and FS water images simultaneously for all types of proton beams. The ranges estimated from the FS water and those calculated with the TPS closely matched, within a difference of several mm. Similar range difference was found between the results estimated from prompt x-ray images and those calculated with the TPS. We confirmed that the simultaneous imaging of luminescence and prompt x-rays were possible during irradiation with spot-scanning proton beams at a clinical dose level. This method can be applied to range estimation as well as comparison with the dose for prompt x-ray imaging or other imaging methods used in therapy with various types of proton beams at a clinical dose level.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Simultaneous imaging of luminescence and prompt x-rays during irradiation with spot-scanning proton beams at clinical dose level

Yamamoto¹,

Yamashita²,

Kobashi³

et al. 2023

Biomed. Phys. Eng. Express

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“…The difference between measured distribution and dose distribution was large for the images measured with the 4-mm-diameter collimator due to the lower spatial resolution. However, as shown previously, the distributions could be corrected to the dose distribution by using a neural network employing deep learning approaches [40,41].…”

Section: Discussionmentioning

confidence: 99%

Advantages of using larger-diameter pinhole collimator for prompt X-ray imaging during irradiation with carbon ions

et al. 2022

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Prompt secondary electron bremsstrahlung X-ray (prompt X-ray) imaging using a low-energy X-ray camera is a promising method for observing a beam shape from outside the subject. However, the images measured within short times suffer from statistical noise. Consequently, we performed prompt X-ray imaging with higher sensitivity using a larger-diameter pinhole collimator and compared the results with those of a conventional collimator. Prompt X-ray imaging was conducted during irradiation with pencil beams of 241.5-MeV/n carbon ions to a water phantom. A newly developed X-ray camera with a 4-mm diameter as well as conventional 1.5-mm-diameter pinhole collimators was used for the imaging in list mode, and we compared the prompt X-ray images, energy spectra, and time count rate curves between 1.5-mm-diameter and 4-mm-diameter pinhole collimators. The prompt X-ray images taken with the 4-mm-diameter pinhole collimators had ∼7 times higher sensitivity with 70 % lower offset fractions originating from the prompt gamma photons. Furthermore, the ranges were more precisely estimated with the 4-mm collimator than with the 1.5-mm collimator. The energy spectra showed less contamination by tungsten-characteristic X-rays for the 4-mm pinhole collimator. Even for images measured with 0.1-s intervals, the beam shapes and time count rate curves could be obtained with less statistical noise using the 4-mm-diameter pinhole collimators. The use of the 4-mm-diameter pinhole collimator attached to the X-ray camera had advantages for prompt X-ray imaging with high sensitivity and low background, enabling us to image the beams even with short-time measurements.

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“…Prompt X-ray imaging during irradiation of proton beam with an X-ray camera was easier to perform compared with prompt gamma photons because the energy of the prompt X-rays detected by the imaging method was low (20-60 keV). The disadvantages of prompt X-ray images are the absence of a Bragg peak in the images due to the low energy of the prompt X-rays produced from the secondary electrons of protons at the Bragg peak and higher attenuation of the X-rays in the subjects [27][28][29][30][31][32][33][34][35][36][37]. However, high contrast imaging of the beams has been achieved using an X-ray camera that employs an adequate scintillator and a pinhole with shield [27][28][29][30][31][32][33][34][35][36][37]39].…”

Section: Jinst 18 P07046mentioning

confidence: 99%

“…Other methods involve imaging of the positrons produced in a subject using a positron emission tomography (PET) system, a high-energy gamma camera, or a Compton camera [13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Imaging using prompt secondary electron bremsstrahlung X-rays (hereinafter, simply prompt X-rays) emitted from a subject during proton beam irradiation is also a promising method for beam-range and beam-shape estimation [27][28][29][30][31][32][33][34][35][36][37].…”

Section: Introductionmentioning

confidence: 99%

Simultaneous imaging of prompt gamma photons and prompt X-rays during irradiation of proton beams to human torso phantom at clinical dose level

Yamamoto

Yamashita²,

Kobashi³

et al. 2023

J. Inst.

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Although both prompt gamma photon and prompt X-ray imaging are promising methods for observing a beam shape and estimating the range of the beam from outside a subject, the images using these two methods have not been compared under realistic conditions such as in a human torso phantom. To clarify the imaging capability of prompt gamma photon and prompt X-ray imaging, simultaneous imaging with these methods was conducted during irradiation by proton beams to a human torso phantom at clinical dose level. After a human torso phantom was set on the bed of a proton therapy system, proton pencil beams of three different energies at clinical dose level and a patient planning beam for prostate cancer were used to irradiate the phantom. Prompt gamma photons and prompt X-rays emitted from the phantom were simultaneously imaged by a developed gamma camera and an X-ray camera during irradiation with proton beams to the human torso phantom. For all of the tested beams, we could obtain the beam shapes of prompt gamma photons and prompt X-rays images. The ranges could be estimated within a difference of 11 mm and 14 mm from the calculated dose for prompt gamma photon and prompt X-ray images, respectively. For both types of images, time sequential images and time count rate curves could be derived. We could clarify the imaging capabilities of prompt gamma photons and prompt X-rays were different by the simultaneous imaging during proton irradiation to a human torso phantom. Although both methods had advantages and disadvantages, we confirmed that both methods are promising for beam imaging in a torso phantom and also for future clinical use in proton therapy.

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Deep learning-based in vivo dose verification from proton-induced secondary-electron-bremsstrahlung images with various count level

Cited by 13 publications

References 34 publications

Simultaneous imaging of luminescence and prompt x-rays during irradiation with spot-scanning proton beams at clinical dose level

Simultaneous imaging of luminescence and prompt x-rays during irradiation with spot-scanning proton beams at clinical dose level

Advantages of using larger-diameter pinhole collimator for prompt X-ray imaging during irradiation with carbon ions

Simultaneous imaging of prompt gamma photons and prompt X-rays during irradiation of proton beams to human torso phantom at clinical dose level

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