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Farr JB, Moyers MF, Allgower CE, Bues M, Hsi WC, Jin H, Mihailidis DN, Lu HM, Newhauser WD, Sahoo N, Slopsema R, Yeung D, Zhu XR. Clinical commissioning of intensity-modulated proton therapy systems: Report of AAPM Task Group 185. Med Phys 2020; 48:e1-e30. [PMID: 33078858 DOI: 10.1002/mp.14546] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 08/17/2020] [Accepted: 08/18/2020] [Indexed: 02/06/2023] Open
Abstract
Proton therapy is an expanding radiotherapy modality in the United States and worldwide. With the number of proton therapy centers treating patients increasing, so does the need for consistent, high-quality clinical commissioning practices. Clinical commissioning encompasses the entire proton therapy system's multiple components, including the treatment delivery system, the patient positioning system, and the image-guided radiotherapy components. Also included in the commissioning process are the x-ray computed tomography scanner calibration for proton stopping power, the radiotherapy treatment planning system, and corresponding portions of the treatment management system. This commissioning report focuses exclusively on intensity-modulated scanning systems, presenting details of how to perform the commissioning of the proton therapy and ancillary systems, including the required proton beam measurements, treatment planning system dose modeling, and the equipment needed.
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Affiliation(s)
- Jonathan B Farr
- Department of Medical Physics, Applications of Detectors and Accelerators to Medicine, Meyrin, 1217, Switzerland
| | | | - Chris E Allgower
- Richard L. Roudebush VA Medical Center, Indianapolis, IN, 46202, USA
| | - Martin Bues
- Department of Radiation Oncology, Mayo Clinic, Scottsdale, AZ, 85259, USA
| | - Wen-Chien Hsi
- University of Florida Proton Therapy Institute, University of Florida, Jacksonville, FL, 32206, USA
| | - Hosang Jin
- Department of Radiation Oncology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Dimitris N Mihailidis
- Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Hsiao-Ming Lu
- Department of Radiation Oncology, Hefei Ion Medical Center, 1700 Changning Avenue, Gaoxin District, Hefei, Anhui, 230088, China
| | - Wayne D Newhauser
- Department of Physics & Astronomy, Louisiana State University, Baton Rouge, LA, 70803, USA.,Mary Bird Perkins Cancer Center, Baton Rouge, LA, 70809, USA
| | - Narayan Sahoo
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
| | - Roelf Slopsema
- Department of Radiation Oncology, Emory Proton Therapy Center, Emory University, Atlanta, GA, 30322, USA
| | - Daniel Yeung
- Saudi Proton Therapy Center, King Fahad Medical City, Riyadh, Riyadh Province, 11525, Saudi Arabia
| | - X Ronald Zhu
- Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, TX, 77030, USA
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Wang X, Meier D, Taguchi K, Wagenaar DJ, Patt BE, Frey EC. Material separation in x-ray CT with energy resolved photon-counting detectors. Med Phys 2011; 38:1534-46. [PMID: 21520865 DOI: 10.1118/1.3553401] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
PURPOSE The objective of the study was to demonstrate that, in x-ray computed tomography (CT), more than two types of materials can be effectively separated with the use of an energy resolved photon-counting detector and classification methodology. Specifically, this applies to the case when contrast agents that contain K-absorption edges in the energy range of interest are present in the object. This separation is enabled via the use of recently developed energy resolved photon-counting detectors with multiple thresholds, which allow simultaneous measurements of the x-ray attenuation at multiple energies. METHODS To demonstrate this capability, we performed simulations and physical experiments using a six-threshold energy resolved photon-counting detector. We imaged mouse-sized cylindrical phantoms filled with several soft-tissue-like and bone-like materials and with iodine-based and gadolinium-based contrast agents. The linear attenuation coefficients were reconstructed for each material in each energy window and were visualized as scatter plots between pairs of energy windows. For comparison, a dual-kVp CT was also simulated using the same phantom materials. In this case, the linear attenuation coefficients at the lower kVp were plotted against those at the higher kVp. RESULTS In both the simulations and the physical experiments, the contrast agents were easily separable from other soft-tissue-like and bone-like materials, thanks to the availability of the attenuation coefficient measurements at more than two energies provided by the energy resolved photon-counting detector. In the simulations, the amount of separation was observed to be proportional to the concentration of the contrast agents; however, this was not observed in the physical experiments due to limitations of the real detector system. We used the angle between pairs of attenuation coefficient vectors in either the 5-D space (for non-contrast-agent materials using energy resolved photon-counting acquisition) or a 2-D space (for contrast agents using energy resolved photon-counting acquisition and all materials using dual-kVp acquisition) as a measure of the degree of separation. Compared to dual-kVp techniques, an energy resolved detector provided a larger separation and the ability to separate different target materials using measurements acquired in different energy window pairs with a single x-ray exposure. CONCLUSIONS We concluded that x-ray CT with an energy resolved photon-counting detector with more than two energy windows allows the separation of more than two types of materials, e.g., soft-tissue-like, bone-like, and one or more materials with K-edges in the energy range of interest. Separating material types using energy resolved photon-counting detectors has a number of advantages over dual-kVp CT in terms of the degree of separation and the number of materials that can be separated simultaneously.
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Affiliation(s)
- Xiaolan Wang
- Department of Radiology and Radiological Science, Johns Hopkins University, Baltimore, Maryland 21287, USA.
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Kim S, Hernandez A, Alhassen F, Pivovaroff M, Cho HM, Gould RG, Seo Y. Multi-Material Decomposition using Low-Current X-Ray and a Photon-Counting CZT Detector. IEEE NUCLEAR SCIENCE SYMPOSIUM CONFERENCE RECORD. NUCLEAR SCIENCE SYMPOSIUM 2011:4735-4738. [PMID: 23503709 PMCID: PMC3598635 DOI: 10.1109/nssmic.2011.6154705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We developed and evaluated an x-ray photon-counting imaging system using an energy-resolving cadmium zinc telluride (CZT) detector coupled with application specific integrated circuit (ASIC) readouts. This x-ray imaging system can be used to identify different materials inside the object. The CZT detector has a large active area (5×5 array of 25 CZT modules, each with 16×16 pixels, cover a total area of 200 mm × 200 mm), high stopping efficiency for x-ray photons (~ 100 % at 60 keV and 5 mm thickness). We explored the performance of this system by applying different energy windows around the absorption edges of target materials, silver and indium, in order to distinguish one material from another. The photon-counting CZT-based x-ray imaging system was able to distinguish between the materials, demonstrating its capability as a radiation-spectroscopic decomposition system.
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Affiliation(s)
- Sangtaek Kim
- Physics Research Laboratory, University of California, San Francisco, San Francisco, CA 94107 USA
| | - Andrew Hernandez
- Physics Research Laboratory, University of California, San Francisco, San Francisco, CA 94107 USA
| | - Fares Alhassen
- Physics Research Laboratory, University of California, San Francisco, San Francisco, CA 94107 USA
| | | | | | - Robert G. Gould
- Physics Research Laboratory, University of California, San Francisco, San Francisco, CA 94107 USA
| | - Youngho Seo
- Physics Research Laboratory, University of California, San Francisco, San Francisco, CA 94107 USA
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