Purpose: Anatomical motion, both cyclical and aperiodic, can impact the dose delivered during external beam radiation. In this work, we evaluate the use of a research version of the clinical TomoTherapy dose calculator to calculate dose with intrafraction rigid motion. We also evaluate the feasibility of a method of motion compensation for helical tomotherapy using the jaws and MLC.
Methods: Treatment plans were created using the TomoTherapy treatment planning system. Dose was recalculated for several simple rigid motion traces including a 4 mm step motion applied either longitudinally or transversely, and a sinusoidal motion. The calculated dose volumes were compared to dose measurements that were performed by translating the phantom with the same motion traces used in the calculations. Measurements were made using film and ion chambers. Finally, the delivery plans were modified to compensate for the motion by sweeping the jaws for longitudinal motion and shifting the MLC leaves for transverse motion, and the calculations and measurements were repeated.
Results: A transverse step motion shifted the dose that was delivered after the step occurred, but otherwise did not impact the dose distribution. Film measurements agreed with dose calculations to within 2%/2 mm for 99% of dose points within the 50% isodose line. A shift in the MLC leaf delivery pattern successfully compensated for the step motion to within the 3 mm accuracy allowed by the finite leaf widths. A longitudinal step motion impacted the dose in the interior of the target volume to a degree that was dependent on the planning field width and step size. Film measurements agreed with dose calculations to within 2%/2 mm for 98% of dose points within the 50% isodose line. Shifts in the jaw position successfully compensated for the longitudinal step motion. Sinusoidal (breathing-like) motion was also studied, with similar results.
Conclusions: A research version of the clinical TomoTherapy dose calculator has been shown to accurately calculate the dose from treatment plans delivered in the presence of arbitrary rigid motion. Modifications to the delivery plan using jaw and MLC leaf shifts that follow the motion can successfully compensate for the target motion.
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http://dx.doi.org/10.1002/mp.12655 | DOI Listing |
Tissue Eng Regen Med
January 2025
Pen-Tung Sah Institute of Micro-Nano Science and Technology, Xiamen University, Xiamen, 361102, Fujian, China.
Background: The contraction behaviors of cardiomyocytes (CMs), especially contraction synchrony, are crucial factors reflecting their maturity and response to drugs. A wider field of view helps to observe more pronounced synchrony differences, but the accompanied greater computational load, requiring more computing power or longer computational time.
Methods: We proposed a method that directly correlates variations in optical field brightness with cardiac tissue contraction status (CVB method), based on principles from physics and photometry, for rapid video analysis in wide field of view to obtain contraction parameters, such as period and contraction propagation direction and speed.
Head Neck Pathol
January 2025
Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Purpose: Recurrent diffuse-type tenosynovial giant cell tumor: Clinical presentation, Diagnosis, and Management.
Background: Tenosynovial giant cell tumor (TGCT), is a neoplasm arising from synovial joints, bursae, or tendon sheaths. The initial clinical symptoms are vague and non-diagnostic.
Nano Lett
January 2025
Institut für Festkörperelektronik, Technische Universität Wien, Gußhausstraße 25, 1040 Vienna, Austria.
We synthesized and spectroscopically investigated monolayer (ML) C on the topological insulator (TI) BiTe. This C/BiTe heterostructure is characterized by an excellent translational order in a novel (4 × 4) C superstructure on a (9 × 9) cell of BiTe. Angle-resolved photoemission spectroscopy (ARPES) of C/BiTe reveals that ML C accepts electrons from the TI at room temperature, but no charge transfer occurs at low temperatures.
View Article and Find Full Text PDFKnee Surg Sports Traumatol Arthrosc
January 2025
Sports Medicine Service, Beijing Jishuitan Hospital, Capital Medical University, Beijing, China.
Purpose: To propose a new sign of patellar maltracking in recurrent patellar dislocation (RPD) and compare the differences in lower limb rotational and bony structural abnormalities among the different signs.
Patients And Methods: A retrospective study included 279 patients (mean age: 22 years; female: 81%) who underwent primary surgery for RPD over the past 4 years was performed. The patients were grouped based on the characteristics of patellar tracking: low-, moderate- and high-grade J-sign.
Chromatin remodeling enzymes play a crucial role in the organization of chromatin, enabling both stability and plasticity of genome regulation. These enzymes use a Snf2-type ATPase motor to move nucleosomes, but how they translocate DNA around the histone octamer is unclear. Here we use cryo-EM to visualize the continuous motion of nucleosomal DNA induced by human chromatin remodeler SNF2H, an ISWI family member.
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