Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

Iqbal, Khalid; Gillin, M; Summers, P.; Dhanesar, S; Gifford, Kent A; Buzdar, Saeed Ahmad

doi:10.1259/bjr.20130390

Cited by 12 publications

(20 citation statements)

References 16 publications

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“…This study describes dosimetric commissioning tests used for the Varian ProBeam system at MPTC and SPTC and provides results that can be used as a reference for future ProBeam sites. Although the tests described here are not complete, they are similar to those used before and should provide useful benchmarks.…”

Section: Introductionmentioning

confidence: 99%

Comparison of multi‐institutional Varian ProBeam pencil beam scanning proton beam commissioning data

Langner

Eley

Dong

et al. 2017

J Applied Clin Med Phys

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PurposeCommissioning beam data for proton spot scanning beams are compared for the first two Varian ProBeam sites in the United States, at the Maryland Proton Treatment Center (MPTC) and Scripps Proton Therapy Center (SPTC). In addition, the extent to which beams can be matched between gantry rooms at MPTC is investigated.MethodBeam data for the two sites were acquired with independent dosimetry systems and compared. Integrated depth dose curves (IDDs) were acquired with Bragg peak ion chambers in a 3D water tank for pencil beams at both sites. Spot profiles were acquired at different distances from the isocenter at a gantry angle of 0° as well as a function of gantry angles. Absolute dose calibration was compared between SPTC and the gantries at MPTC. Dosimetric verification of test plans, output as a function of gantry angle, monitor unit (MU) linearity, end effects, dose rate dependence, and plan reproducibility were compared for different gantries at MPTC.ResultsThe IDDs for the two sites were similar, except in the plateau region, where the SPTC data were on average 4.5% higher for lower energies. This increase in the plateau region decreased as energy increased, with no marked difference for energies higher than 180 MeV. Range in water coincided for all energies within 0.5 mm. The sigmas of the spot profiles in air were within 10% agreement at isocenter. This difference increased as detector distance from the isocenter increased. Absolute doses for the gantries measured at both sites were within 1% agreement. Test plans, output as function of gantry angle, MU linearity, end effects, dose rate dependence, and plan reproducibility were all within tolerances given by TG142.ConclusionBeam data for the two sites and between different gantry rooms were well matched.

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Section: Introductionmentioning

confidence: 99%

Comparison of multi‐institutional Varian ProBeam pencil beam scanning proton beam commissioning data

Langner

Eley

Dong

et al. 2017

J Applied Clin Med Phys

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“…When considering how to most effectively treat patients with proton therapy, different treatment planning system provide different advantages and disadvantages . These differences in different treatment planning systems were discussed in various articles for photons and for protons . Pencil beam scanning can also be simulated with Monte Carlo models, although this is more time consuming and not practical for everyday treatment planning.…”

Section: Introductionmentioning

confidence: 99%

A comparison of two pencil beam scanning treatment planning systems for proton therapy

Langner

Mundis

Strauss

et al. 2017

J Applied Clin Med Phys

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ObjectiveAnalytical dose calculation algorithms for Eclipse and Raystation treatment planning systems (TPS), as well as a Raystation Monte Carlo model are compared to corresponding measured point doses.MethodThe TPS were modeled with the same beam data acquired during commissioning. Thirty‐five typical plans were made with each planning system, 31 without range shifter and four with a 5 cm range shifter. Point doses in these planes were compared to measured doses.ResultsThe mean percentage difference for all plans between Raystation and Eclipse were 1.51 ± 1.99%. The mean percentage difference for all plans between TPS models and measured values are −2.06 ± 1.48% for Raystation pencil beam (PB), −0.59 ± 1.71% for Eclipse and −1.69 ± 1.11% for Raystation monte carlo (MC). The distribution for the patient plans were similar for Eclipse and Raystation MC with a P‐value of 0.59 for a two tailed unpaired t‐test and significantly different from the Raystation PB model with P = 0.0013 between Raystation MC and PB. All three models faired markedly better if plans with a 5 cm range shifter were ignored. Plan comparisons with a 5 cm range shifter give differences between Raystation and Eclipse of 3.77 ± 1.82%. The mean percentage difference for 5 cm range shifter plans between TPS models and measured values are −3.89 ± 2.79% for Raystation PB, −0.25 ± 3.85% for Eclipse and 1.55 ± 1.95% for Raystation MC.ConclusionBoth Eclipse and Raystation PB TPS are not always accurate within ±3% for a 5 cm range shifters or for small targets. This was improved with the Raystation MC model. The point dose calculations of Eclipse, Raystation PB, and Raystation MC compare within ±3% to measured doses for the other scenarios tested.

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“…The literature on comprehensive PSQA programs for patients receiving particle therapy is limited [ 6 , 8 , 9 ]. Some publications have reported only specific aspects of PSQA [ 10 , 11 , 12 , 13 , 14 , 15 ]. For example, some works focused on either dosimetric detector development or evaluation: Karger et al [ 13 ] developed a detector based on a block of ionization chambers for 3D dosimetric verification of treatment plans in intensity-modulated heavy ion therapy, and Arjomandy et al [ 10 ] reported the use of a 2D-ICAD for verification of patient-specific dose distributions in proton therapy.…”

Section: Discussionmentioning

confidence: 99%

“…Other studies investigated the validation of the TPS for particle therapy. Iqbal et al [ 11 ] reported QA evaluation of SSPT with an anthropomorphic prostate phantom, and Jäkel et al [ 12 ] published QA for a TPS for scanned ion beam therapy. Lomax et al [ 6 ] summarized their experience with an SSPT PSQA program, which included treatment field-specific dose verifications, for 166 patients.…”

Section: Discussionmentioning

confidence: 99%

“…However, knowledge in this area is lacking, as few reports have comprehensively described PSQA programs for patients receiving particle therapy [ 6 , 8 , 9 ]. Most reports on PSQA programs only described specific aspects of such programs [ 10 , 11 , 12 , 13 , 14 , 15 ]. In this article, we review our efforts in developing an effective and efficient PSQA program for SSPT.…”

Section: Introductionmentioning

confidence: 99%

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Towards Effective and Efficient Patient-Specific Quality Assurance for Spot Scanning Proton Therapy

Zhu

Mackin

et al. 2015

Cancers

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An intensity-modulated proton therapy (IMPT) patient-specific quality assurance (PSQA) program based on measurement alone can be very time consuming due to the highly modulated dose distributions of IMPT fields. Incorporating independent dose calculation and treatment log file analysis could reduce the time required for measurements. In this article, we summarize our effort to develop an efficient and effective PSQA program that consists of three components: measurements, independent dose calculation, and analysis of patient-specific treatment delivery log files. Measurements included two-dimensional (2D) measurements using an ionization chamber array detector for each field delivered at the planned gantry angles with the electronic medical record (EMR) system in the QA mode and the accelerator control system (ACS) in the treatment mode, and additional measurements at depths for each field with the ACS in physics mode and without the EMR system. Dose distributions for each field in a water phantom were calculated independently using a recently developed in-house pencil beam algorithm and compared with those obtained using the treatment planning system (TPS). The treatment log file for each field was analyzed in terms of deviations in delivered spot positions from their planned positions using various statistical methods. Using this improved PSQA program, we were able to verify the integrity of the data transfer from the TPS to the EMR to the ACS, the dose calculation of the TPS, and the treatment delivery, including the dose delivered and spot positions. On the basis of this experience, we estimate that the in-room measurement time required for each complex IMPT case (e.g., a patient receiving bilateral IMPT for head and neck cancer) is less than 1 h using the improved PSQA program. Our experience demonstrates that it is possible to develop an efficient and effective PSQA program for IMPT with the equipment and resources available in the clinic.

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Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

Cited by 12 publications

References 16 publications

Comparison of multi‐institutional Varian ProBeam pencil beam scanning proton beam commissioning data

Comparison of multi‐institutional Varian ProBeam pencil beam scanning proton beam commissioning data

A comparison of two pencil beam scanning treatment planning systems for proton therapy

Towards Effective and Efficient Patient-Specific Quality Assurance for Spot Scanning Proton Therapy

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