gms | German Medical Science

48th Meeting of the Particle Therapy Co-Operative Group

Particle Therapy Co-Operative Group (PTCOG)

28.09. - 03.10.2009, Heidelberg

Development of Pencil Beam Scanning Nozzle System

Meeting Abstract

  • T. Asaba - Quantum equipment division, Sumitomo Heavy Industries, Ltd., Soubiraki-cho, Niihama, Ehime, Japan
  • T. Tachikawa - Quantum equipment division, Sumitomo Heavy Industries, Ltd., Soubiraki-cho, Niihama, Ehime, Japan
  • T. Ochi - Quantum equipment division, Sumitomo Heavy Industries, Ltd., Soubiraki-cho, Niihama, Ehime, Japan
  • M. Yamada - Quantum equipment division, Sumitomo Heavy Industries, Ltd., Soubiraki-cho, Niihama, Ehime, Japan
  • T. Nishio - National Cancer Center Hospital East, Kashiwanoha, Kashiwa, Chiba, Japan
  • T. Ogino - National Cancer Center Hospital East, Kashiwanoha, Kashiwa, Chiba, Japan

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog013

DOI: 10.3205/09ptcog013, URN: urn:nbn:de:0183-09ptcog0136

Published: September 24, 2009

© 2009 Asaba et al.
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Outline

Text

Purpose: Several types of pencil beam scanning system for proton therapy have been developed and applied to clinical treatment. In case of pencil beam scanning using cyclotron as the proton source, it is common to use continuous scanning method. Then scanning speed and beam current are modulated simultaneously to make dose distributions. However, it is not reliable to modulate beam current quickly by the internal ion source of cyclotron.

SHI has developed a new scanning nozzle to solve the problem. In this presentation, we report the design of this nozzle and the result of its performance test.

Methods: The design specifications of this nozzle are as follows:

Spot size: σ = within 5 mm
Maximum range: Over 320 mm
Field size: Over 300 mm x 400 mm
SOBP with: Over 280 mm
Dose uniformity: Within ±2.5%

SHI has designed the scanning nozzle to achieve these specifications by simple and reliable scanning method. The beam current is constant within a layer by a feedback control and the scanning speed is modulated to form the dose distributions of each layer.

This nozzle was designed and manufactured as a modified version of the multi-purpose nozzle. It was installed in the gantry No.1 of NCCHE proton therapy system for its performance tests in collaboration with NCCHE.

Results: In the performance tests the dose distributions were measured using a water phantom with multi-channel array of ionization chambers and it was confirmed that all design specifications noted above were fulfilled.

Conclusions: We developed the scanning nozzle that has new scanning control method. The beam current is constant within a layer and the scanning speed is modulated in each layer. The required specifications were confirmed by the performance test.