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

New Eyeball Phantom for Verification of Patient Positioning and Eye Fixation at the IFJ PAN eye proton facility

Meeting Abstract

  • author T. Kajdrowicz - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • L. Czopyk - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • T. Cywicka-Jakiel - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • B. Dulny - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • T. Horwacik - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • P. Olko - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • M. Ptaszkiewicz - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland
  • J. Swakon - Institute of Nuclear Physics Polish Academy of Science, Krakow, Poland

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog101

DOI: 10.3205/09ptcog101, URN: urn:nbn:de:0183-09ptcog1018

Published: September 24, 2009

© 2009 Kajdrowicz et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Outline

Text

Proton treatment of ocular melanoma requires high precision of patient positioning in order to achieve good tumor control and to maintain patient’s vision. Design of a positioning system consists typically of patient chair, thermoplastic mask, bite block, set of orthogonal X-ray lamps, fixation light and treatment planning applications.

The aim of this work was to develop and test an eye phantom that enables verification of patient positioning and eye fixation system. The eye phantom consist of an eyeball, a stand mounted to the patient chair and a set of pointing devices. Beside the chair movements along its axes, there are additional three degrees of rotational freedom available including eye torsion [1]. As a result, design of the phantom allows to reproduce almost every possible treatment position of an eye.

A set of treatment plans has been prepared using Eclipse Ocular Proton Planning [2] software to cover wide range of tumor cases. For each of the plans a series of X-ray simulations has been conducted using the eye phantom and original tantalum clips same as in real patient treatment preparation. In each of the simulations the phantom was pointing in a different fixation direction and its twist angle (torsion) was slightly adjusted.

Comparison of planned and actual phantom data showed a good agreement of chair positions (within 0.1 mm), gazing angles (within 0.5°) and eye torsion angle (within 1°) for each of the prepared plans. Additionally, it has been proved that the phantom can handle wide range of fixation light positions (up to 40° polar) and eye torsion (from -10° to +10°).

The newly developed eye phantom to be routinely applied for verification of the eye tumor patient positioning. It is planned to use this phantom in QA procedures and personnel training at IFJ PAN treatment facility.

ACKNOWLEDGMENTS

Supported by a grant from Iceland, Lichtenstein and Norway through the EEA Financial Mechanism and the Norwegian Financial Mechanism.


References

1.
Goitein M, Miller T. Planning proton therapy of the eye. Med Phys. 1983;10(3):275-83.
2.
Eclipse Ocular Proton Planning Reference Guide. VMS Inc; 2007.