Status of the Midwest Proton Radiotherapy Institute

Anferov, V. A.; Collins, JD Dawn; Friesel, D.L.; Jones, W. P.; Katuin, J.; Klein, Susan Blakeley; Schreuder, A

doi:10.1109/pac.2003.1289013

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…Details of the beamline configuration between the trunk line and the fixed beamline room can be found elsewhere. 13 At MPRI, the treatments are prescribed in range rather than energy. Before each treatment commences, the range and range spread measured with the MLFC are compared against predefined values, and treatments are not allowed if the disagreement is greater than Ϯ0.1 cm.…”

Section: Iia Description Of Beamlinementioning

confidence: 99%

Energy spectrum control for modulated proton beams

Hsi¹,

Moyers²,

Nichiporov

et al. 2009

Medical Physics

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In proton therapy delivered with range modulated beams, the energy spectrum of protons entering the delivery nozzle can affect the dose uniformity within the target region and the dose gradient around its periphery. For a cyclotron with a fixed extraction energy, a rangeshifter is used to change the energy but this produces increasing energy spreads for decreasing energies. This study investigated the magnitude of the effects of different energy spreads on dose uniformity and distal edge dose gradient and determined the limits for controlling the incident spectrum. A multilayer Faraday cup ͑MLFC͒ was calibrated against depth dose curves measured in water for nonmodulated beams with various incident spectra. Depth dose curves were measured in a water phantom and in a multilayer ionization chamber detector for modulated beams using different incident energy spreads. Some nozzle entrance energy spectra can produce unacceptable dose nonuniformities of up to Ϯ21% over the modulated region. For modulated beams and small beam ranges, the width of the distal penumbra can vary by a factor of 2.5. When the energy spread was controlled within the defined limits, the dose nonuniformity was less than Ϯ3%. To facilitate understanding of the results, the data were compared to the measured and Monte Carlo calculated data from a variable extraction energy synchrotron which has a narrow spectrum for all energies. Dose uniformity is only maintained within prescription limits when the energy spread is controlled. At low energies, a large spread can be beneficial for extending the energy range at which a single range modulator device can be used. An MLFC can be used as part of a feedback to provide specified energy spreads for different energies.

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Section: Iia Description Of Beamlinementioning

confidence: 99%

Energy spectrum control for modulated proton beams

Hsi¹,

Moyers²,

Nichiporov

et al. 2009

Medical Physics

View full text Add to dashboard Cite

show abstract

“…The transmission of accelerated particles that pass through such a rangeshifter made of carbon and then continue to the patient has been reported to range from 72% at 230 MeV to 3% at 100 MeV (Flanz et al, 1998). At least one institution places individual range-shifters in each side beamline directed to each treatment room rather than a single range-shifter in the main trunk line (Anferov, 2003;Anferov et al, 2003). This arrangement allows the main trunk line to maintain a constant, well-tuned, single energy.…”

Section: Introductionmentioning

confidence: 99%