Clinical characterization of a proton beam continuous uniform scanning system with dose layer stacking
- 14 October 2008
- journal article
- Published by Wiley in Medical Physics
- Vol. 35 (11), 4945-4954
- https://doi.org/10.1118/1.2982248
Abstract
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%.Keywords
Funding Information
- National Institutes of Health (C06 RR17407-01)
This publication has 29 references indexed in Scilit:
- A computational implementation and comparison of several intensity modulated proton therapy treatment planning algorithmsMedical Physics, 2008
- Comparison of intensity modulated x-ray therapy and intensity modulated proton therapy for selective subvolume boosting: a phantom studyPhysics in Medicine & Biology, 2007
- Treatment planning and verification of proton therapy using spot scanning: Initial experiencesMedical Physics, 2004
- The Clinical Potential of Intensity Modulated Proton TherapyZeitschrift für Medizinische Physik, 2004
- Secondary neutron dose during proton therapy using spot scanningInternational Journal of Radiation Oncology*Biology*Physics, 2002
- Intensity modulated radiotherapy with charged particle beams: Studies of inverse treatment planning for rotation therapyMedical Physics, 2000
- A treatment planning inter-comparison of proton and intensity modulated photon radiotherapyRadiotherapy and Oncology, 1999
- Spot scanning system for proton radiotherapyMedical Physics, 1980
- Flattening of proton dose distributions for large‐field radiotherapyMedical Physics, 1977
- Range modulators for protons and heavy ionsNuclear Instruments and Methods, 1975