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Published on: December 28, 2017
Magnetic resonance imaging for precise radiotherapy of small laboratory animals
Thorsten Frenzel1, Michael Gerhard Kaul2, Thomas Michael Ernst2
1Universitätsklinikum Hamburg-Eppendorf, Ambulanzzentrum des UKE GmbH, Bereich Strahlentherapie, Martinistraße 52, 20246 Hamburg, Germany; Universitätsklinikum Hamburg-Eppendorf, Zentrum für Experimentelle Medizin, Institut für Anatomie und Experimentelle Morphologie, Martinistraße 52, 20246 Hamburg, Germany.
Aims:
Radiotherapy of small laboratory animals (SLA) is often not as precisely applied as in humans. Here we describe the use of a dedicated SLA magnetic resonance imaging (MRI) scanner for precise tumor volumetry, radiotherapy treatment planning, and diagnostic imaging in order to make the experiments more accurate.
Methods And Materials:
Different human cancer cells were injected at the lower trunk of pfp/rag2 and SCID mice to allow for local tumor growth. Data from cross sectional MRI scans were transferred to a clinical treatment planning system (TPS) for humans. Manual palpation of the tumor size was compared with calculated tumor size of the TPS and with tumor weight at necropsy. As a feasibility study MRI based treatment plans were calculated for a clinical 6MV linear accelerator using a micro multileaf collimator (μMLC). In addition, diagnostic MRI scans were used to investigate animals which did clinical poorly during the study.
Results:
MRI is superior in precise tumor volume definition whereas manual palpation underestimates their size. Cross sectional MRI allow for treatment planning so that conformal irradiation of mice with a clinical linear accelerator using a μMLC is in principle feasible. Several internal pathologies were detected during the experiment using the dedicated scanner.
Conclusion:
MRI is a key technology for precise radiotherapy of SLA. The scanning protocols provided are suited for tumor volumetry, treatment planning, and diagnostic imaging.
