Premium
SU‐FF‐T‐651: Acceptance and Clinical Commissioning of a Uniform‐Scanning Proton Therapy System
Author(s) -
Slopsema R,
Lin L,
Mathot G,
Adam B,
Rexford J,
Li Z
Publication year - 2009
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.3182149
Subject(s) - proton therapy , sobp , pencil beam scanning , bragg peak , imaging phantom , dosimetry , radiation treatment planning , ionization chamber , aperture (computer memory) , pencil (optics) , dose profile , optics , beam (structure) , nuclear medicine , materials science , medical physics , physics , radiation therapy , acoustics , medicine , ionization , surgery , ion , quantum mechanics
Purpose: Acceptance and clinical commissioning of a uniform‐scanning proton therapy system. Method and Materials: Uniform Scanning (US) is one of the proton delivery modes of the gantry‐mounted Universal Nozzle (IBA). In US, a large pencil beam is scanned in a rectangular pattern to cover a field‐specific aperture. The spread‐out Bragg peak (SOBP) is created using energy‐stacking. The system is commissioned by measurement of depth dose curves and lateral profiles using a variety of devices, including 3D water phantom, Matrixx detector, and multi‐layer ionization chamber (IBA Dosimetry). Treatment planning system is Varian Eclipse. Results: Target sizes of up to 40cm in the inline and 30cm in the crossline direction can be covered. Range can be varied continuously between 4.0 and 32.4 g/cm2; beams can be modulated up to skin. Dose uniformity is ⩽3% in the uniform region. Range accuracy is found to be ⩽1.5mm over the complete range span. The treatment‐planning dose matches measurement within 3% in the uniform region. In the proximal region, treatment planning underestimates the dose by up to 6%. Difference between planned and measured in‐water penumbra is found to be less than 1mm, for air gaps smaller than 15cm. Conclusion: Uniform scanning meets its design specifications and has successfully been commissioned for clinical use. Treatment sites that benefit include deep‐seated prostate, large sarcoma, and cranial‐spinal targets.