Commissioning of output factors for uniform scanning proton beams

Zheng, Yuanshui; Ramirez, E; Mascia, Anthony; Ding, Xiaoning; Okoth, B; Zeidan, O.; Hsi, W. C.; Harris, Ben; Schreuder, A; Keole, Sameer R.

doi:10.1118/1.3569581

Cited by 36 publications

(36 citation statements)

References 22 publications

(19 reference statements)

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“…Each spread‐out Bragg peak (SOBP) is delivered layer by layer, with the most distal layer delivered first and shallower layers delivered later. More details on our system delivery were described by Zheng et al ( 6 ) …”

Section: Methodsmentioning

confidence: 99%

A novel daily QA system for proton therapy

Ding

Zheng

Zeidan

et al. 2013

J Applied Clin Med Phys

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We describe the design and use of a daily quality assurance (QA) system for proton therapy. The QA system is designed to check the overall readiness of proton therapy system consistently within certain reference tolerances by a home‐made QA device (the QA device). The QA device is comprised of a commercially available QA device, rf‐Daily QA 3, a home‐made acrylic phantom, a set of acrylic compensators with various thicknesses, and a mechanical indexing jig. The indexing jig indexes the rf‐Daily QA 3, as well as the acrylic phantom, onto the patient treatment couch. Embedded fiducial markers in the acrylic phantom are used to check X‐ray image quality and positioning alignment accuracy of the imaging system. The rf‐Daily QA 3 is used to check proton beam output, range and symmetry with one single beam delivery. We developed in‐house software to calculate beam range and symmetry, based on various ion chambers' readings inside the rf‐Daily QA 3. With a single setup and one beam irradiation, the QA system is employed to check couch movement, laser alignment, image registration, and reference proton beam characteristics. The simplicity and robustness of this QA system allows for a total QA time of less than 20 minutes per room. The system has been in use at three proton therapy centers since June 2009.PACS numbers: 87.55.Qr, 87.53.Bn

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Section: Methodsmentioning

confidence: 99%

A novel daily QA system for proton therapy

Ding

Zheng

Zeidan

et al. 2013

J Applied Clin Med Phys

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“…A detailed description on the uniform scanning proton therapy system has been provided elsewhere. 6,7 In order to study the impact of heterogeneities on lateral penumbra, we manufactured one homogenous phantom and four inhomogeneous phantoms (Figure 1) utilizing solid-water plates (CIRS, Norfolk, VA), air, and poly-vinyl chloride (PVC) tile. …”

Section: Methodsmentioning

confidence: 99%

Impact of heterogeneities on lateral penumbra in uniform scanning proton therapy

Rana

Singh

2013

Int J Cancer Ther Oncol

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Purpose: In the treatment planning of uniform scanning proton therapy, an aperture block is designed for each beam with a margin, which typically includes the lateral penumbra measured in water (homogenous) medium. However, during real proton therapy treatment, protons may pass through tissues of different densities within the patient's body before they are stopped. The main aim of this study was to investigate the dependency of lateral penumbra on low-and high-density heterogeneities placed in the plateau and spread-out Bragg peak (SOBP) regions. Method: The measurements were performed by placing radiographic films at the isocenter (center of SOBP), and each proton beam was delivered with 150 monitor units using standard beam conditions of the institution. Results and Conclusion: The preliminary results from this study showed that the lateral penumbra of uniform scanning proton beams was less sensitive to the inhomogeneities introduced in the protons beam path. The low-density heterogeneity in the plateau region had more impact on the lateral penumbra when compared to the low-density in the SOBP region. In contrast, the placement of high-density heterogeneity (whether in the plateau or SOBP region) produced a very minimal difference. The overall difference in lateral penumbra among different phantoms was within ±1 mm.

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“…A further major advantage of the Northwestern Medicine facility is the capability of the IBA universal nozzle to wobble a pencil beam broadened by an initial scatterer (about 4 to 7 cm FWHM) horizontally and vertically, a delivery mode called “uniform scanning” [20]. This allows us to expose uniformly and predictably the part of the phantom covered by the scanner acceptance with fewer protons emitted outside of the imaging region.A problem with running pCT has been that the required intensity is so low that the accelerator operators cannot monitor the beam.…”

Section: Data Acquisitionmentioning

confidence: 99%

A Fast Experimental Scanner for Proton CT: Technical Performance and First Experience With Phantom Scans

Johnson

Bashkirov

DeWitt

et al. 2016

IEEE Trans. Nucl. Sci.

103

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We report on the design, fabrication, and first tests of a tomographic scanner developed for proton computed tomography (pCT) of head-sized objects. After extensive preclinical testing, pCT is intended to be employed in support of proton therapy treatment planning and pre-treatment verification in patients undergoing particle-beam therapy. The scanner consists of two silicon-strip telescopes that track individual protons before and after the phantom, and a novel multistage scintillation detector that measures a combination of the residual energy and range of the proton, from which we derive the water equivalent path length (WEPL) of the protons in the scanned object. The set of WEPL values and the associated paths of protons passing through the object over a 360° angular scan are processed by an iterative, parallelizable reconstruction algorithm that runs on modern GP-GPU hardware. In order to assess the performance of the scanner, we have performed tests with 200 MeV protons from the synchrotron of the Loma Linda University Medical Center and the IBA cyclotron of the Northwestern Medicine Chicago Proton Center. Our first objective was calibration of the instrument, including tracker channel maps and alignment as well as the WEPL calibration. Then we performed the first CT scans on a series of phantoms. The very high sustained rate of data acquisition, exceeding one million protons per second, allowed a full 360° scan to be completed in less than 10 minutes, and reconstruction of a CATPHAN 404 phantom verified accurate reconstruction of the proton relative stopping power in a variety of materials.

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Commissioning of output factors for uniform scanning proton beams

Cited by 36 publications

References 22 publications

A novel daily QA system for proton therapy

A novel daily QA system for proton therapy

Impact of heterogeneities on lateral penumbra in uniform scanning proton therapy

A Fast Experimental Scanner for Proton CT: Technical Performance and First Experience With Phantom Scans

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