Uncertainty analysis of a Compton camera imaging system for radiation therapy dose reconstruction

Mundy, Daniel W.; Herman, Michael

doi:10.1118/1.3399777

Cited by 12 publications

(6 citation statements)

References 22 publications

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“…Quantification of deposited dose based on scatter image intensity has not been tested, possibly because it is also complicated by the multiple-scattering blurring. Energy-discriminating Compton cameras may be able to perform a statistical determination, although processing may take days of computation (Mundy and Herman 2010). The analytical simulation method described here may provide a faster iterative route through which agreement of experimental and simulated images would allow for 3D quantification of deposited dose, even when multiple scattering is present.…”

Section: Discussionmentioning

confidence: 99%

“…And, tracking of breathing motion is particularly important during high-dose rate deliveries (>2 times higher than conventional 400–600 MU min −1 dose rates), where high signal-to-noise scatter images may possibly be acquired fast enough for tracking. Aside from previously-proposed, potential 3D dose tracking uses (Mundy and Herman 2010), which may be challenged by computational time and attenuation, there are other possible applications of scatter imaging. For example, beam alignment during cranial, head and neck, or tangential breast treatment might be verified based on air in sinuses, trachea, or lung, respectively.…”

Section: Discussionmentioning

confidence: 99%

“…The scatter probability and scattered photon energy can be analytically calculated based on the incident photon energy, the scattering angle, and the electron density of the material. An image may be formed by identifying the origin of the scattered photons through proper collimation (Lale 1959, Farmer and Collins 1971, Clarke et al 1976, Harding and Tischler 1986), by mapping energies to spatial coordinates (Norton 1994; Lenti 2008), with a Compton camera (Mundy and Herman 2010), or through coded-aperture techniques (MacCabe et al 2013). Of these, pinhole collimation (Redler et al 2015) is a conceptually simple technique that is amenable to experiment and simulation.…”

Section: Introductionmentioning

confidence: 99%

“…The high fluence (and resulting dose) required for these measurements and the development of kilovoltage computed tomography (CT) made scatter electron density mapping obsolete (Battista and Bronskill 1981). Because the intensity is dependent on the number of incident photons, scatter imaging may also provide a method for quantitatively measuring the delivered 3D dose (Mundy and Herman 2010). …”

Section: Introductionmentioning

confidence: 99%

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Characterization of Compton-scatter imaging with an analytical simulation method

et al. 2018

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By collimating the photons scattered when a megavoltage therapy beam interacts with the patient, a Compton-scatter image may be formed without the delivery of an extra dose. To characterize and assess the potential of the technique, an analytical model for simulating scatter images was developed and validated against Monte Carlo (MC). For three phantoms, the scatter images collected during irradiation with a 6 MV flattening-filter-free therapy beam were simulated. Images, profiles, and spectra were compared for different phantoms and different irradiation angles. The proposed analytical method simulates accurate scatter images up to 1000 times faster than MC. Minor differences between MC and analytical simulated images are attributed to limitations in the isotropic superposition/convolution algorithm used to analytically model multiple-order scattering. For a detector placed at 90° relative to the treatment beam, the simulated scattered photon energy spectrum peaks at 140–220 keV, and 40–50% of the photons are the result of multiple scattering. The high energy photons originate at the beam entrance. Increasing the angle between source and detector increases the average energy of the collected photons and decreases the relative contribution of multiple scattered photons. Multiple scattered photons cause blurring in the image. For an ideal 5 mm diameter pinhole collimator placed 18.5 cm from the isocenter, 10 cGy of deposited dose (2 Hz imaging rate for 1200 MU min−1 treatment delivery) is expected to generate an average 1000 photons per mm2 at the detector. For the considered lung tumor CT phantom, the contrast is high enough to clearly identify the lung tumor in the scatter image. Increasing the treatment beam size perpendicular to the detector plane decreases the contrast, although the scatter subject contrast is expected to be greater than the megavoltage transmission image contrast. With the analytical method, real-time tumor tracking may be possible through comparison of simulated and acquired patient images.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of Compton-scatter imaging with an analytical simulation method

et al. 2018

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“…where 𝐸 1 is the recoil electron energy and 𝐸 2 is the scattered photon energy; 𝑚 e denotes the electron's rest mass and 𝑐 denotes the light velocity. The ARM includes uncertainties derived from the energy resolution, detector geometry and the doppler broadening effect [51]. The contributions to the geometric uncertainty are the detector's spatial resolution and its placement.…”

Section: Performance Of Compton Camera With a Monte Carlo Simulationmentioning

confidence: 99%

Double photon coincidence crosstalk reduction method for multi-nuclide Compton imaging

Uenomachi¹,

Shimazoe²,

Takahashi³

2022

J. Inst.

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Compton imaging based on Compton scattering kinematics has the potential to visualize multi-nuclides by discriminating the total energy of Compton scattering and photoelectric absorption events. This feature enables us to perform multi-tracer imaging that reflects different functional information in nuclear medicine, resulting in a definitive diagnosis and being useful for biological and medical research. One of the challenges with multi-nuclide imaging is the crosstalk artifacts caused by scattered photons of higher energy gamma-rays. In this study, we investigated the potential benefits of the double photon coincidence detection as a drastic crosstalk reduction method. Coincidence detection of successive gamma-rays can differentiate nuclides and reduce the background caused by other nuclides' gamma-rays because some nuclides emit two or more gamma-rays in rapid succession. In this study, we focused on the coincidence detection of a Compton event and a photoelectric absorption event, and we showed simultaneous double photon emitter imaging of 111In and 177Lu with a ring-type Compton imaging system. The artifacts caused by other nuclides' gamma-rays were reduced by extracting Compton events coincident with photoelectric absorption events. The coincidence Compton images demonstrated a signal-to-background ratio improvement of 1.1–1.7 times over the one of no-coincidence Compton images, despite a drop in intrinsic detection efficiency of the order of 10-2. This strategy of directly reducing crosstalk will be useful in other combinations imaging such as of 111In (or 177Lu) and a positron emission tomography nuclide.

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Feasibility study of Compton imaging for PGAA

Chen-Mayer

Brown

Yang

2019

J Radioanal Nucl Chem

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Uncertainty analysis of a Compton camera imaging system for radiation therapy dose reconstruction

Cited by 12 publications

References 22 publications

Characterization of Compton-scatter imaging with an analytical simulation method

Characterization of Compton-scatter imaging with an analytical simulation method

Double photon coincidence crosstalk reduction method for multi-nuclide Compton imaging

Feasibility study of Compton imaging for PGAA

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