4D Treatment (Planning) Workshop
at GSI Darmstadt
Theorieseminarraum -
Information

Title:	Dr.
Family Name:	Knopf
First Name:	Antje-Christin
Gender:	female
E-Mail:	antje-christin.knopfpsi.ch
Profession:	Physicist
Affiliation for Badge:	PSI, Villigen
Institute:
Address (Street):	Paul Scherrer Istitut
Postal Code, City:	5232 Villigen
Country:	Switzerland
Phone:
Fax:
Arrival Date:	December 8
Departure Date:	December 10
Hotel Information:	NONE
Tour:	No
Author(s):	Antje Knopf, Dirk Boye, Ye Zhang and Tony Lomax
Institute(s):	PSI, Switzerland
Title:	Current status of the 4D treatment planning approach at PSI
Abstract ( 300 words ):	With an optimized proton scanning Gantry under construction, the treatment of moving target sites is an ongoing project at the Center for Proton Therapy at PSI. We developed a 4D dose calculation using a deforming dose grid. This approach is a fast alternative to the common approach of warping time resolved dose distributions to a reference phase and does not relying on 4D CT data sets. To achieve motion information we propose the use of 4D MRI data. With long acquisition times of about 1 hour many breathing cycles can be imaged without any assumption about periodicity. For MRI data acquisition motion including baseline shifts can be studied in patients as well as in volunteers. Motion information is extracted by deformable registration. Studies on the accuracy of different deformable registration algorithms have been performed. Advanced 4D dose calculations show that in the incidence of motion it is not sufficient to use simple target contours defined on one reference 3D CT image. A geometrical target volume definition over all motion phases with an additional adaptation, accounting for proton range variations during the course of treatment is necessary. We programmed a tool, using VTK and ITK, to automatically create appropriate target volumes for scanned proton therapy. The effect of motion varies depending on motion characteristics and plan characteristics. In a systematic treatment planning study we developed a strategy to construct optimal treatment plans for mobile target sides, treated with actively scanned proton beams.

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