Back to Search
Start Over
Automation and uncertainty analysis of a method forin-vivorange verification in particle therapy
- Source :
- Phys Med Biol
- Publication Year :
- 2014
- Publisher :
- IOP Publishing, 2014.
-
Abstract
- We introduce the automation of the range difference calculation deduced from particle-irradiation induced β(+)-activity distributions with the so-called most-likely-shift approach, and evaluate its reliability via the monitoring of algorithm- and patient-specific uncertainty factors. The calculation of the range deviation is based on the minimization of the absolute profile differences in the distal part of two activity depth profiles shifted against each other. Depending on the workflow of PET (positron emission tomography)-based range verification, the two profiles under evaluation can correspond to measured and simulated distributions, or only measured data from different treatment sessions. In comparison to previous work, the proposed approach includes an automated identification of the distal region of interest for each pair of PET depth profiles and under consideration of the planned dose distribution, resulting in the optimal shift distance. Moreover, it introduces an estimate of uncertainty associated to the identified shift, which is then used as weighting factor to “red flag” problematic large range differences. Furthermore, additional patient-specific uncertainty factors are calculated using available CT (computed tomography) data to support the range analysis. The performance of the new method for in-vivo treatment verification in the clinical routine is investigated with in-room PET images for proton therapy as well as with offline PET images for proton and carbon ion therapy. The comparison between measured PET activity distributions and predictions obtained by Monte Carlo simulations or measurements from previous treatment fractions is performed. For this purpose, a total of 15 patient datasets were analyzed, which were acquired at Massachusetts General Hospital and Heidelberg Ion-Beam Therapy Center with in-room PET and offline PET/CT scanners, respectively. Calculated range differences between the compared activity distributions are reported in a two-dimensional map in beam-eye-view. In comparison to previously proposed approaches, the new most-likely-shift method shows more robust results for assessing in-vivo the range from strongly varying PET distributions caused by differing patient geometry, ion beam species, beam delivery techniques, PET imaging concepts and counting statistics. The additional visualization of the uncertainties and the dedicated weighting strategy contribute to the understanding of the reliability of observed range differences and the complexity in the prediction of activity distributions. The proposed method promises to offer a feasible technique for clinical routine of PET-based range verification.
- Subjects :
- Computer science
medicine.medical_treatment
Monte Carlo method
Heavy Ion Radiotherapy
Article
Automation
Region of interest
Proton Therapy
medicine
Range (statistics)
Humans
Radiology, Nuclear Medicine and imaging
Proton therapy
Simulation
Uncertainty analysis
Particle therapy
Radiological and Ultrasound Technology
medicine.diagnostic_test
Phantoms, Imaging
Radiotherapy Planning, Computer-Assisted
Uncertainty
Reproducibility of Results
Weighting
Head and Neck Neoplasms
Positron emission tomography
Positron-Emission Tomography
Tomography, X-Ray Computed
Monte Carlo Method
Algorithm
Algorithms
Subjects
Details
- ISSN :
- 13616560 and 00319155
- Volume :
- 59
- Database :
- OpenAIRE
- Journal :
- Physics in Medicine and Biology
- Accession number :
- edsair.doi.dedup.....4852aca6f0b0c872754cd161fa92ae07