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Rationale And Objectives: A phantom set was devised to evaluate capability of independent component analysis (ICA) as an image filter for magnetic resonance (MR) images to segregate components.
Materials And Methods: Four components (free water [FW], olive oil [OL], 2% and 4% agar gels [2A and 4A, respectively]) were arranged in a phantom set. Seven MR images were obtained with different echo time and repetition time. ICA was performed on 23 combinations of four components. A segregation rate higher than 70% was defined as effective.
Results: Four-component segregation was obtained in 5 of 23 combinations. The best result showed a mean of 87% across the four components. For each component, there were 20 of 23 for FW, 22 for OL, 9 for 2A, and 16 for 4A.
Conclusions: The results demonstrated ICA works as an image filter and provides new contrast images that unambiguously segregate components in MR images. For practical application, the best performance should be obtained when T(1)W, T(2)W, and proton density images are included in the dataset for ICA.
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http://dx.doi.org/10.1016/j.acra.2009.02.011 | DOI Listing |
Med Phys
September 2025
Division of Medical Radiation Physics and Department of Radiation Oncology, Inselspital, Bern University Hospital and University of Bern, Bern, Switzerland.
Background: Radiotherapy workflows conventionally deliver one treatment plan multiple times throughout the treatment course. Non-coplanar techniques with beam angle optimization or dosimetrically optimized pathfinding (DOP) exploit additional degrees of freedom to improve spatial conformality of the dose distribution compared to widely used techniques like volumetric-modulated arc therapy (VMAT). The temporal dimension of dose delivery can be exploited using multiple plans (sub-plans) within one treatment course.
View Article and Find Full Text PDFInt J Comput Assist Radiol Surg
September 2025
Department of Rhythmology, University Heart Center Lübeck, University Hospital Schleswig-Holstein, Ratzeburger Allee 160, Lübeck, 23652, Germany.
Purpose: Ultrasound (US) is commonly used to assess left ventricular motion for examination of heart function. In stereotactic arrhythmia radioablation (STAR) therapy, managing cardiorespiratory motion during radiation delivery requires representation of motion information in computed tomography (CT) coordinates. Similar to conventional US-guided navigation during surgical procedures, 3D US can provide real-time motion data of the radiation target that could be transferred to CT coordinates and then be accounted for by the radiation system.
View Article and Find Full Text PDFArXiv
August 2025
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire.
Purpose: Accurate patient positioning is crucial for precise radiation therapy dose delivery, as errors in positioning can profoundly influence treatment outcomes. This study introduces a novel application for loco-regional tissue deformation tracking via Cherenkov image analysis during fractionated breast cancer radiation therapy. The primary objective of this research was to develop and test an algorithmic method for Cherenkov-based position accuracy quantification, particularly for loco-regional deformations, which do not have an ideal method for quantification during radiation therapy.
View Article and Find Full Text PDFPhys Eng Sci Med
August 2025
Northern Centre for Cancer Care, Newcastle upon Tyne Hospitals NHS Foundation Trust, Freeman Hospital, Freeman Road, Newcastle upon Tyne, NE7 7DN, UK.
To determine the optimum value of head scatter correction factor ([Formula: see text]) used in Radcalc software. The head scatter factors for a selection of multi-leaf collimator fields were measured on a Varian TrueBeam Edge and TrueBeam linear accelerators using an ionisation chamber in a mini-phantom. Radcalc calculated the head scatter values for the same fields.
View Article and Find Full Text PDFEJNMMI Phys
August 2025
Department of Medical Radiation Sciences, Institute of Clinical Sciences, Sahlgrenska Academy at University of Gothenburg, Gula Stråket 2B, Gothenburg, 413 45, Sweden.
Introduction/aim: Terbium-161 (Tb) has emerged as a promising therapeutic radionuclide, yet standardized imaging guidelines are lacking. This study aimed to characterize a SPECT/CT system, currently used in an ongoing clinical trial (BETA PLUS; NCT05359146), focusing on sensitivity, septal penetration, and dead-time effects.
Methods: Measurements were conducted on a Siemens Symbia Intevo system using two collimators: low-energy high-resolution (LEHR) and medium-energy low-penetration (MELP).