title: Gel-based Multimodality (CT/MR) Phantoms for Ion Radiotherapy
creator: Niebuhr, Nina Isabelle
subject: 530
subject: 530 Physics
description: The importance of magnetic resonance imaging (MRI) in radiation therapy (RT) has  been increasing over the past years. In ion RT, due to its high accuracy and sensitivity to  small uncertainties, the treatment planning process based on computed tomography (CT)  is currently extended towards MRI. For exploring the potential of new imaging techniques  (such as MRI) multimodality phantoms are mandatory. Hereby, interaction properties  with photon and ion radiation have to be adjusted independently from the parameters  influencing the MR contrasts.  This Bachelor thesis investigates barium sulfate doped agarose gels as multimodality phantoms  for application in ion RT. 14 gel-phantoms with different combinations of agarose  and barium sulfate concentrations were manufactured. These gels were assessed in dual  energy CT (DECT), MRI and carbon ion range measurements.  DECT parameters were adjustable with barium sulfate while the effect of agarose was  minimal: The effective atomic number (Zeff ) showed values from 7.5 to 10, the electron  density (pe-) relative to water could be varied from 1.00 to 1.03. CT-numbers at 80kV  allowed variation from 0 to 270HU. Adjustment of absolute relaxation times in MR was  possible by varying the agarose concentration. T1 showed a range from 2000 to 2900ms,  T2 was adjustable from from 20 to 120ms. The influence of barium sulfate on feasible relaxation  times was 17% and 12% respectively. The water equivalent path length of carbon  ions could be varied by 3%.  Further investigations with alternative solutes are needed to extend the range of relaxation  times and electron density for more realistic tissue simulation. Agarose gel-phantoms  proved to be stable, easy to handle and allowed independent adjustment of DECT- and  MR-parameters. They enable the production of anthropomorphic multimodality phantoms  for ion RT applications.
date: 2012
type: Bachelor thesis
type: info:eu-repo/semantics/bachelorThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/15479/1/Final_Bachelorthesis_Nina.pdf
identifier: DOI:10.11588/heidok.00015479
identifier: urn:nbn:de:bsz:16-heidok-154792
identifier:   Niebuhr, Nina Isabelle  (2012) Gel-based Multimodality (CT/MR) Phantoms for Ion Radiotherapy.  [Bachelor thesis]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/15479/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng