Use of a two‐dimensional ionization chamber array for proton therapy beam quality assurance

Arjomandy, B.; Ding, Xiaoning; Gillin, Michael

doi:10.1118/1.2963990

Cited by 74 publications

(77 citation statements)

References 12 publications

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“…Arjomandy et al ( 5 ) investigated the use of a high‐resolution 2D ion chamber array for periodic proton beam QA and found that it was appropriate for checking proton beam flatness and symmetry, as well as dose output. However, considering factors such as cost, end‐user training, equipment setup time, and complexity of data interpretation, we believe that high‐resolution 2D arrays are more suitable for monthly and annual QA rather than daily QA.…”

Section: Discussionmentioning

confidence: 99%

“…Some properties of proton beams do not have equivalence in photon therapy, which requires a novel approach to designing efficient QA device and the corresponding workflow. Based on recommendations by various task groups and other studies, ( 1 – 5 ) our daily QA process tests the safety, image‐guided patient position system, and reference proton beam characteristics (output, range, and symmetry). Table 1 is a summary of our daily QA procedures and their corresponding tolerances.…”

Section: Introductionmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

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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“…It provides an accuracy in dose measurements of ∼1% (Ref. 23) and a spatial resolution of ∼1 mm when bilinear interpolation of raw data is performed. All the irradiations were performed with the nozzle in vertical position (gantry at 0…”

Section: B3 Two-dimensional Dose Profile Measurements and Simulatmentioning

confidence: 99%

Experimental validation of the TOPAS Monte Carlo system for passive scattering proton therapy

et al. 2013

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Purpose: TOPAS (TOol for PArticle Simulation) is a particle simulation code recently developed with the specific aim of making Monte Carlo simulations user-friendly for research and clinical physicists in the particle therapy community. The authors present a thorough and extensive experimental validation of Monte Carlo simulations performed with TOPAS in a variety of setups relevant for proton therapy applications. The set of validation measurements performed in this work represents an overall end-to-end testing strategy recommended for all clinical centers planning to rely on TOPAS for quality assurance or patient dose calculation and, more generally, for all the institutions using passive-scattering proton therapy systems. Methods: The authors systematically compared TOPAS simulations with measurements that are performed routinely within the quality assurance (QA) program in our institution as well as experiments specifically designed for this validation study. First, the authors compared TOPAS simulations with measurements of depth-dose curves for spread-out Bragg peak (SOBP) fields. Second, absolute dosimetry simulations were benchmarked against measured machine output factors (OFs). Third, the authors simulated and measured 2D dose profiles and analyzed the differences in terms of field flatness and symmetry and usable field size. Fourth, the authors designed a simple experiment using a half-beam shifter to assess the effects of multiple Coulomb scattering, beam divergence, and inverse square attenuation on lateral and longitudinal dose profiles measured and simulated in a water phantom. Fifth, TOPAS' capabilities to simulate time dependent beam delivery was benchmarked against dose rate functions (i.e., dose per unit time vs time) measured at different depths inside an SOBP field. Sixth, simulations of the charge deposited by protons fully stopping in two different types of multilayer Faraday cups (MLFCs) were compared with measurements to benchmark the nuclear interaction models used in the simulations. Results: SOBPs' range and modulation width were reproduced, on average, with an accuracy of +1, −2 and ±3 mm, respectively. OF simulations reproduced measured data within ±3%. Simulated 2D dose-profiles show field flatness and average field radius within ±3% of measured profiles. The field symmetry resulted, on average in ±3% agreement with commissioned profiles. TOPAS accuracy in reproducing measured dose profiles downstream the half beam shifter is better than 2%. Dose rate function simulation reproduced the measurements within ∼2% showing that the four-dimensional modeling of the passively modulation system was implement correctly and millimeter accuracy can be achieved in reproducing measured data. For MLFCs simulations, 2% agreement was found between TOPAS and both sets of experimental measurements. The overall results show that TOPAS simulations are within the clinical accepted tolerances for all QA measurements performed at our institution. Conclusions: Our Monte Carlo simulations reproduced accurat...

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“…The 2D dose distributions at specific depths were measured with a 2D ion chamber array (MatriXX PT, IBA Dosimetry GmbH, Germany) [23]. More details of the measurements and the experimental uncertainties are described in the references [21][22][23].…”

Section: Measurementsmentioning

confidence: 99%

Inter-comparison of Dose Distributions Calculated by FLUKA, GEANT4, MCNP, and PHITS for Proton Therapy

et al. 2017

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Abstract. The dose distributions from proton pencil beam scanning were calculated by FLUKA, GEANT4, MCNP, and PHITS, in order to investigate their applicability in proton radiotherapy. The first studied case was the integrated depth dose curves (IDDCs), respectively from a 100 and a 226-MeV proton pencil beam impinging a water phantom. The calculated IDDCs agree with each other as long as each code employs 75 eV for the ionization potential of water. The second case considered a similar condition of the first case but with proton energies in a Gaussian distribution. The comparison to the measurement indicates the inter-code differences might not only due to different stopping power but also the nuclear physics models. How the physics parameter setting affect the computation time was also discussed. In the third case, the applicability of each code for pencil beam scanning was confirmed by delivering a uniform volumetric dose distribution based on the treatment plan, and the results showed general agreement between each codes, the treatment plan, and the measurement, except that some deviations were found in the penumbra region. This study has demonstrated that the selected codes are all capable of performing dose calculations for therapeutic scanning proton beams with proper physics settings.

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Use of a two‐dimensional ionization chamber array for proton therapy beam quality assurance

Cited by 74 publications

References 12 publications

A novel daily QA system for proton therapy

A novel daily QA system for proton therapy

Experimental validation of the TOPAS Monte Carlo system for passive scattering proton therapy

Inter-comparison of Dose Distributions Calculated by FLUKA, GEANT4, MCNP, and PHITS for Proton Therapy

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