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

Patch Field Technique in Proton Beam Radiation Therapy for Selective Tissue Avoidance

Meeting Abstract

  • A. Chang - Midwest Proton Radiotherapy Institute, Bloomington, USA
  • M. Fitzek - Midwest Proton Radiotherapy Institute, Bloomington, USA
  • K. Shahnazi - Midwest Proton Radiotherapy Institute, Bloomington, USA
  • A. Thornton - Midwest Proton Radiotherapy Institute, Bloomington, USA

PTCOG 48. Meeting of the Particle Therapy Co-Operative Group. Heidelberg, 28.09.-03.10.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc09ptcog036

doi: 10.3205/09ptcog036, urn:nbn:de:0183-09ptcog0361

Published: September 24, 2009

© 2009 Chang et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Radiation therapy is a long-established modality in the treatment of malignancies. However, the dose distribution of conventional radiation therapy makes it extremely difficult to obtain a strongly concave dose distribution in the situation where a tumor surrounds a critical normal structure. These situations often arise with tumors of the base of skull and spinal canal. Proton beam radiation therapy's unique characteristic allows the creation of such concave dose distributions; this allows delivery of high doses while selectively minimizing dose to the critical normal structure. Unlike conventional radiation therapy with x-rays or gamma rays which are exponentially attenuated, proton beam radiation therapy has no exit dose after the Bragg peak. The width of the peak as well as its depth in tissue can be precisely modulated with a variety of compensators. The laterality of the field can be easily tailored similar to conventional radiation therapy. Patch field combinations consist of multiple fields of proton beam radiation therapy that take advantage of this unique stopping ability of proton radiation. These field combinations typically consist of a single or multiple "patch" fields which are modified such that its distal edge abuts onto the lateral edge of a "long" field. Multiple sets of patch field combinations can be used to deliver high doses of radiation to target volumes while minimizing dose to normal tissue structures. This allows highly conformal radiation therapy to elegantly treat tumors surrounding or encasing critical normal tissue (Figure 1 [Fig. 1]).