Multichannel detectors for profile measurements in clinical proton fields

Nichiporov, D.; Solberg, K.; Hsi, W. C.; Wolanski, M.; Mascia, Anthony; Farr, J; Schreuder, A

doi:10.1118/1.2746513

Cited by 37 publications

(36 citation statements)

References 13 publications

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“…As an alternative to above scanning water phantom measurements, multilayer ionization chambers (MLIC) can speed up data acquisition of depth‐dose curves of clinical particle beams. This has been demonstrated in the past 7 , 8 , 9 , 10 . Consequently, we evaluate if a large electrode MLIC (brand name ‘Giraffe’, IBA Dosimetry) can replace the combination of an integral chamber and scanning water phantom.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of detectors for acquisition of pristine depth‐dose curves in pencil beam scanning

Bäumer

Koska

Lambert

et al. 2015

J Applied Clin Med Phys

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Acquisition of quasi‐monoenergetic ("pristine") depth‐dose curves is an essential task in the frame of commissioning and quality assurance of a proton therapy treatment head. For pencil beam scanning delivery modes this is often accomplished by measuring the integral ionization in a plane perpendicular to the axis of an unscanned beam. We focus on the evaluation of three integral detectors: two of them are plane‐parallel ionization chambers with an effective radius of 4.1 cm and 6.0 cm, respectively, mounted in a scanning water phantom. The third integral detector is a 6.0 cm radius multilayer ionization chamber. The experimental results are compared with the corresponding measurements under broad field conditions, which are performed with a small radius plane‐parallel chamber and a small radius multilayer ionization chamber. We study how a measured depth‐dose curve of a pristine proton field depends on the detection device, by evaluating the shape of the depth‐dose curve, the relative charge collection efficiency, and intercomparing measured ranges. Our results show that increasing the radius of an integral chamber from 4.1 cm to 6.0 cm increases the collection efficiency by 0%–3.5% depending on beam energy and depth. Ranges can be determined by the large electrode multilayer ionization chamber with a typical uncertainty of 0.4 mm on a routine basis. The large electrode multilayer ionization chamber exhibits a small distortion in the Bragg Peak region. This prohibits its use for acquisition of base data, but is tolerable for quality assurance. The good range accuracy and the peak distortion are characteristics of the multilayer ionization chamber design, as shown by the direct comparison with the small electrode counterpart.PACS number: 87.55.Qr

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Section: Introductionmentioning

confidence: 99%

Evaluation of detectors for acquisition of pristine depth‐dose curves in pencil beam scanning

Bäumer

Koska

Lambert

et al. 2015

J Applied Clin Med Phys

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“…Both the MLIC and MPIC share common instrumentation electronics and a computerized data acquisition system. 17 Another transverse detector used is a commercial product providing 1020 vented pixel ionization chambers in a 32 ϫ 32 grid with 7.6 mm of separation between the centers of the chambers ͑IBA Dosimetry, Schwarzenbruck, Germany, model I'mRT MatriXX͒.…”

Section: Iib1 Relative Dosimetrymentioning

confidence: 99%

“…Some of these detectors were designed, built, and evaluated during the commissioning, and were reported in a separate publication. 17 Not reported here is the system dose calibration stability with time, dose rate, and monitor units. Also, mechanical alignment results, snout proton leakage, and out of field dose results are omitted.…”

Section: Introductionmentioning

confidence: 99%

Clinical characterization of a proton beam continuous uniform scanning system with dose layer stacking

et al. 2008

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A proton beam delivery system on a gantry with continuous uniform scanning and dose layer stacking at the Midwest Proton Radiotherapy Institute has been commissioned and accepted for clinical use. This paper was motivated by a lack of guidance on the testing and characterization for clinical uniform scanning systems. As such, it describes how these tasks were performed with a uniform scanning beam delivery system. This paper reports the methods used and important dosimetric characteristics of radiation fields produced by the system. The commissioning data include the transverse and longitudinal dose distributions, penumbra, and absolute dose values. Using a 208 MeV cyclotron's proton beam, the system provides field sizes up to 20 and 30 cm in diameter for proton ranges in water up to 27 and 20 cm, respectively. The dose layer stacking method allows for the flexible construction of spread-out Bragg peaks with uniform modulation of up to 15 cm in water, at typical dose rates of 1 -3 Gy/ min. For measuring relative dose distributions, multielement ion chamber arrays, small-volume ion chambers, and radiographic films were employed. Measurements during the clinical commissioning of the system have shown that the lateral and longitudinal dose uniformity of 2.5% or better can be achieved for all clinically important field sizes and ranges. The measured transverse penumbra widths offer a slight improvement in comparison to those achieved with a double scattering beam spreading technique at the facility. Absolute dose measurements were done using calibrated ion chambers, thermoluminescent and alanine detectors. Dose intercomparisons conducted using various types of detectors traceable to a national standards laboratory indicate that the measured dosimetry data agree with each other within 5%.

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“…Most of the systems in use are based on single or arrays of ionization chambers and on films, which are certainly precise but suffer for lengthy procedures. Nichiporov et al 4 examined the usefulness of multichannel detectors, while in many other studies [5][6][7][8][9] , film dosimetry has been proposed to verify dose distributions and perform QA in proton therapy. Film dosimetry, shown to be highly precise, does not give immediate results because the procedures required for preparing, scanning, calibration, and off-line analysis are time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Quality assurance of carbon ion and proton beams: A feasibility study for using the 2D MatriXX detector

et al. 2016

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Purpose: The quality assurance (QA) procedures in particle therapy centers with active beam scanning make extensive use of films, which do not provide immediate results. The purpose of this work is to verify whether the 2D MatriXX detector by IBA Dosimetry has enough sensitivity to replace films in some of the measurements. Methods: MatriXX is a commercial detector composed of 32×32 parallel plate ionization chambers designed for pre-treatment dose verification in conventional radiation therapy. The detector and GAFCHROMIC® films were exposed simultaneously to a 131.44 MeV proton and a 221.45 MeV/u carbon-ion therapeutic beam at the CNAO therapy center of Pavia -Italy, and the results were analyzed and compared. Results: The sensitivity MatriXX on the beam position, beam width and field flatness was investigated. For the first two quantities, a method for correcting systematic uncertainties, dependent on the beam size, was developed allowing to achieve a position resolution equal to 230 µm for carbon ions and less than 100 µm for protons. The beam size and the field flatness measured using MatriXX were compared with the same quantities measured with the irradiated film, showing a good agreement. Conclusions:The results indicate that a 2D detector such as MatriXX can be used to measure many parameters of a scanned ion beam quickly and precisely and suggest that the QA would benefit from a new protocol where the MatriXX detector is added to the existing systems.

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Multichannel detectors for profile measurements in clinical proton fields

Cited by 37 publications

References 13 publications

Evaluation of detectors for acquisition of pristine depth‐dose curves in pencil beam scanning

Evaluation of detectors for acquisition of pristine depth‐dose curves in pencil beam scanning

Clinical characterization of a proton beam continuous uniform scanning system with dose layer stacking

Quality assurance of carbon ion and proton beams: A feasibility study for using the 2D MatriXX detector

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