Combined 3D segmentation of PET and CT concerning dosimetry and treatment management in targeted radionuclide therapy and external beam radiotherapy

To improve diagnosis and individual planning of radiotherapy treatments for External Beam Radiotherapy (EBRT) and Targeted Radionuclide Therapy (TRT), combined analysis of both anatomical (e.g. CT or MRI) and functional (PET, SPECT) image-data is of increasing relevance. The task of volume segmentation - defining anatomical structures and tumours and precise estimation of their volumes - is crucial for the accuracy of calculated absorbed doses, as well in EBRT as for TRT.

 

Figure 1: Threshold-limited maximum intensity projection (MIP) of PET-study of bronchus carcinoma of the medial lobe
T2 N2 M0 and corresponding GTV/PTVs:
A: ventral field, B: corresponding left view and C: overlay with Sum-Projection of co-registered CT-dataset.

 

To implement patient-specific dosimetry for TRT on an automated base, calculations have to be performed based on both known spatial and temporal distribution of the radioactive agent and established electron density distribution in the nearest neighbourhood of spots with relevant source concentrations. Due to the nature of TRT, dose distributions show high dose gradients, making these calculations rather critical.

As TRT is an inherently multidisciplinary approach and volume segmentation is a shared central task for TRT and EBRT, this project is designed in collaboration of multiple institutes. The development of stochastic methods, based on Monte-Carlo-Calculation together with new deterministic calculation methods is provided by Medical Physics Department of ARCs. Biophysical aspects are supported by the Faculty of Natural Sciences of the University Salzburg. Development of new combined methods for automatic segmentation of co-registered PET and CT–studies as data-input for dosimetric calculations is covered by radART institute and the Department of Radiotherapy and Radio-Oncology of the Paracelsus Medical University in Salzburg. Their clinical experience and the immediate integration of the results in daily clinical routine allow for proper assessment and evaluation of the new methods.

 

Scientific Computing

 

book cover Following the curriculum of Michael T. Heath from the University of Illinois a number of lectures from Prof. M. Vajtersic at the Salzburg University are presenting a broad overviw of numerical methods for solving all major problems in scientific computing, including linear and nonlinear equations, least squares, eigenvalues, optimization, interpolation, integration, ordinary and partial differential equation, fast Fourier transform, and random number generators.
 

The lectures are dealing with topics higly relevant for computional problems to be solved  in scientific research of the University Clinic of Radiotherapy and the radART Institute concerning Image Guided Radiotherapy. Methods have to be developed and implemented in a propriate manner, considering risks of usage of computional software in medical applications. Additional effort has to be spent in acceleration of computional algorithms for their implementation in time-critical processes within clinical workflow of planning and treating patients with high-energy linear accelerators.

 

Lecture notes of M.T.Heaths book Scientific Computing, An Introductory Survey

 

CE-Certification of Software for Imaging and Managing Processes in Clinical Radiotherpeutic Practice - QA of Medical Devices

RT² - Visual Control is a high-sophisticated software for managing clinical workflow in the University Clinic of Radiotherapy and Radio-Oncology of the Paracelsus Medical University Salzburg. RT² was developed by radART Institute, mainly by it’s administrative head, Mag. H. Deutschmann. Efforts are empowered to assure highest levels of Quality Assurance during the whole life-cycle of every single unit.

Installing and running an appropriate Quality Management System, covering demands of Software LifeCycle Management, analyzing and integrating clinical processes are the major tasks of this project.

Focal point of Life Cycle Mangagement and Risk-Management are medical requirements and regulations. Focal point of clinical processes partly rests on patients comfort. However, risk management and assurance of high standards of medical requirements are dealed with high priority.