4D in-beam positron emission tomography for verification of motion-compensated ion beam therapy

Journal Article · Tue Sep 15 04:00:00 EDT 2009 · Medical Physics

DOI:https://doi.org/10.1118/1.3196236· OSTI ID:22102091

Parodi, Katia; Saito, Nami; Chaudhri, Naved; Richter, Christian; Durante, Marco; Enghardt, Wolfgang; Rietzel, Eike; Bert, Christoph ^[1]

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1. Department of Radiation Oncology and Heidelberg Ion Beam Therapy Centre (HIT), University Clinic of Heidelberg, Im Neuenheimer Feld 450, 69120 Heidelberg (Germany)

Purpose: Clinically safe and effective treatment of intrafractionally moving targets with scanned ion beams requires dedicated delivery techniques such as beam tracking. Apart from treatment delivery, also appropriate methods for validation of the actual tumor irradiation are highly desirable. In this contribution the feasibility of four-dimensionally (space and time) resolved, motion-compensated in-beam positron emission tomography (4DibPET) was addressed in experimental studies with scanned carbon ion beams. Methods: A polymethyl methracrylate block sinusoidally moving left-right in beam's eye view was used as target. Radiological depth changes were introduced by placing a stationary ramp-shaped absorber proximal of the moving target. Treatment delivery was compensated for motion by beam tracking. Time-resolved, motion-correlated in-beam PET data acquisition was performed during beam delivery with tracking the moving target and prolonged after beam delivery first with the activated target still in motion and, finally, with the target at rest. Motion-compensated 4DibPET imaging was implemented and the results were compared to a stationary reference irradiation of the same treatment field. Data were used to determine feasibility of 4DibPET but also to evaluate offline in comparison to in-beam PET acquisition. Results: 4D in-beam as well as offline PET imaging was found to be feasible and offers the possibility to verify the correct functioning of beam tracking. Motion compensation of the imaged {beta}{sup +}-activity distribution allows recovery of the volumetric extension of the delivered field for direct comparison with the reference stationary condition. Observed differences in terms of lateral field extension and penumbra in the direction of motion were typically less than 1 mm for both imaging strategies in comparison to the corresponding reference distributions. However, in-beam imaging retained a better spatial correlation of the measured activity with the delivered dose. Conclusions: 4DibPET is a feasible and promising method to validate treatment delivery of scanned ion beams to moving targets. Further investigations will focus on more complex geometries and treatment planning studies with clinical data.

• OSTI ID: 22102091
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 9 Vol. 36; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
62 RADIOLOGY AND NUCLEAR MEDICINE
CARBON IONS
COMPARATIVE EVALUATIONS
DATA ACQUISITION
FOUR-DIMENSIONAL CALCULATIONS
ION BEAMS
NEOPLASMS
PLANNING
POSITRON COMPUTED TOMOGRAPHY
RADIATION DOSES
RADIOTHERAPY
TIME RESOLUTION
VERIFICATION