Flattening of proton dose distributions for large‐field radiotherapy

Koehler, Andreas; Schneider, Robert J.; Sisterson, J. M.

doi:10.1118/1.594317

Cited by 202 publications

(115 citation statements)

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“…2 Proton delivery techniques can be categorized as passive or active in the delivery of a uniform dose to the treatment volume. Passive techniques, which have been most commonly used in the clinical setting, including prostate cancer treatment, 3,4 spread the beam laterally using a combination of gold and Lexan foils 5 and in depth by using a rotating plastic wheel. 6 The beam is then collimated by brass or Cerrobend ® apertures and its penetration depth is varied by means of a wax bolus.…”

Section: Introductionmentioning

confidence: 99%

Out‐of‐field dose equivalents delivered by proton therapy of prostate cancer

2007

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Measurements were performed to assess the dose equivalent outside a primary proton treatment field, using a silicon-on-insulator ͑SOI͒ microdosimeter. The SOI microdosimeter was placed on the surface of an anthropomorphic phantom and dose equivalents were determined as a function of lateral distance from a typical passively scattered and modulated prostate treatment field. Measurements were also completed within a polystyrene plate phantom as a function of depth for a distance of 5 cm from the field edge, as function of lateral distance from field edge at two different depths, and as a function of distance from the distal edge on the central beam axis. The dose equivalent at the surface of the anthropomorphic phantom decreases from 3.9 to 0.18 mSv/Gy when the lateral distance from the proton field edge increases from 2.5 to 60 cm. Measurements along the proton depth dose distribution at a constant distance of 5 cm from the primary field edge indicate a decrease in dose equivalent as a function of depth, with a 38% decrease relative to the surface dose at a depth of 5 cm in polystyrene. Measurements completed as a function of lateral distance from the primary field at two separate depths within polystyrene illustrate a convergence of the dose equivalent at approximately 20 cm from the primary field edge. Past the distal edge of the spreadout Bragg peak dose equivalents decrease exponentially for increasing distance, with an initial value of 1.6 mSv/Gy at 0.6 cm from the distal edge. Silicon microdosimetry measurements were also compared with published results obtained utilizing different measurement techniques. This study demonstrates the applicability of SOI microdosimetry in determining the dose equivalent outside proton treatment fields, and provides valuable information on the dose equivalent both at the surface and at depth experienced by prostate cancer patients treated with protons.

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Section: Introductionmentioning

confidence: 99%

Out‐of‐field dose equivalents delivered by proton therapy of prostate cancer

2007

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“…This system can be made in three basic methods which are occluding ring 6) , dual ring double scattering 7) and compensated contoured double scattering methods.…”

Section: Introductionmentioning

confidence: 99%

“…To achieve SOBP, several types of ridge filters are employed in front of proton beam to give desired homogeneous dose in depth 4) . In lateral direction, broad and uniform beam profile is produced using double scattering technique [5][6][7] or single scattering in combination with beam wobbling system 8) . The wobbling system includes two separate magnets in series for horizontal and vertical deflecting of protons along their central axis in a circular fashion.…”

Section: Introductionmentioning

confidence: 99%

A Study on Beam Flattening Based on Compact Double Scatterer Applicable to Rotational Beam Irradiation System in the Proton Therapy Facility at CYRIC, Tohoku University

Torshabi

Terakawa

Ishii

et al. 2011

Progress in Nuclear Science and Technology

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Proton therapy facility at Cyclotron and Radioisotope Center (CYRIC) in Tohoku University includes a horizontal beam line, currently used for research studies, and also a rotational beam irradiation system which is under construction. This system will be able to change the beam irradiation angle from 0 to 180 degree around the target and the beam delivery on the target volume is done passively using scatterers and ridge filters. In this rotational beam irradiation system due to the limitation on the available space between the beam exit window to the target location, a compact compensated contoured double scattering system was proposed to create the lateral homogeneous dose profile. This work represents the evaluation of this compact double scatterer and its application to the rotational beam irradiation system. The experiments were performed using the horizontal beam line by considering to the status of the rotational beam irradiation system in the target room 5 at CYRIC. The experimental results represent the lateral dose distribution with a proper treatment region which is in a good agreement with simulated data.

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“…Gottschalk have been most active and successful in developing the scattering foil techniques [1,3] .…”

Section: Medical Beam-scanning Research Centersmentioning

confidence: 99%

“…This delivery system, used with protons [1,3], and helium ions [2], is termed a Passive system, as the filling of the treatment volume is done entirely with elements placed in the beam and ;:, Lissajous scanner [5] (Fig lc) is a variant of the Wobbler, the magnets are driven with saw-tooth waves of unrelated frequencies. The Raster Scanner [6] (Fig ld) has a fast sweep saw-tooth drive and a slow sweep single pass for each spill from the accelerator.…”

Section: Magnetically Scanned Beamsmentioning

confidence: 99%

Magnetically scanned ion beams for radiation therapy

Alonso

1989

Nuclear Instruments and Methods in Physics Research Section B:

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The advantageous physical characteristics of slowing-down and stopping charged particle ion beams have been demonstrated to be highly desirable for application to radiation therapy.Specifically, the prospect of concentrating the dose delivered into a sharply-defined treatment volume while keeping to a minimum the total dose to tissues outside this volume is most appealing, offering very significant improvements over what is possible with established radiation therapy techniques. Key to achieving this physical dose distribution in an actual treatment setting is the technique used for delivering the beam into the patient. Magnetically scanned beams are emerging as the technique of choice, but daunting problems remain still in achieving the utmost theoretically possible dose distributions.

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Flattening of proton dose distributions for large‐field radiotherapy

Cited by 202 publications

References 0 publications

Out‐of‐field dose equivalents delivered by proton therapy of prostate cancer

Out‐of‐field dose equivalents delivered by proton therapy of prostate cancer

A Study on Beam Flattening Based on Compact Double Scatterer Applicable to Rotational Beam Irradiation System in the Proton Therapy Facility at CYRIC, Tohoku University

Magnetically scanned ion beams for radiation therapy

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