Background & Objective: To date, the low-melting point lead blocks are commonly used as a beam modifier for the accurate three-dimensional (3D) radiotherapy in China. However, care should be taken when using blocks even though they are verified on the specified simulator or linear accelerator before treatment. This is because that those verifications are only performed under the gantry angle of 0 degree. For the oblique gantry angles, the block may shift in the tray leading to the positioning error. In this study, we explored the influence of gantry position on the accuracy of lead block localization, and the relative quality control methods were also provided.
Methods: After rotating the gantry to 90 degrees and setting the collimator angle to 0 degree on a Siemens linear accelerator, a crosshair was marked on the plastic base of the lead block fitted to the tray according to the crosshair of light field of the linear accelerator. Then the discrepancy between the base crosshair and the light crosshair was investigated for different gantry positions and collimator angles.
Results: There was clearance between the plastic base of the lead block and the block tray. As for some collimator angles at oblique gantry positions, the lead block shifted in the tray due to the gravity. This led to the position error of blocked radiation fields from 0 up to 3.6 mm at the isocenter plane.
Conclusions: Accurately marking the crosshair on the plastic base of the lead block is an effective method of correctly fixing the lead block influenced by the plastic base as well as of double checking the accuracy of the localization of the lead block. The positioning error of oblique gantry positions can be minimized by limiting the collimator to some degrees which makes the block tray opening to the ceiling or parallel to the ground while the bisector of the restrictive angle points slanting to the ceiling (that is, the first baseline of the block tray points inclined or right to the ceiling).
Download full-text PDF |
Source |
|---|
Publication Analysis
Top Keywords
Similar Publications
Electrically Switchable Multi-Stable Topological States Enabled by Surface-Induced Frustration in Nematic Liquid Crystal Cells.
Adv Mater
January 2025
Liquid Crystals and Photonics Group, Department of Electronics and Information Systems, Ghent University, Technologiepark-Zwijnaarde 126, Ghent, 9052, Belgium.
In liquid crystal (LC) cells, the surface patterning directs the self-assembly of the uniaxial building blocks in the bulk, enabling the design of stimuli-response optical devices with various functionalities. The combination of different anchoring patterns at both substrates can lead to surface induced frustration, preventing a purely planar and defect-free configuration. In cells with crossed assembly of rotating anchoring patterns, elastic deformations allow to obtain a defect-free bulk configuration, but an electrical stimulus can induce disclination lines.
View Article and Find Full Text PDFResearch on Mine-Personnel Helmet Detection Based on Multi-Strategy-Improved YOLOv11.
Sensors (Basel)
December 2024
School of Coal Engineering, Shanxi Datong University, Datong 037000, China.
In the complex environment of fully mechanized mining faces, the current object detection algorithms face significant challenges in achieving optimal accuracy and real-time detection of mine personnel and safety helmets. This difficulty arises from factors such as uneven lighting conditions and equipment obstructions, which often lead to missed detections. Consequently, these limitations pose a considerable challenge to effective mine safety management.
View Article and Find Full Text PDFDiscovery of a tribenzophenazine analog for binding to the KRAS mRNA G-quadruplex structures in the cisplatin-resistant non-small cell lung cancer.
J Biol Chem
January 2025
Nation-Regional Engineering Lab for Synthetic Biology of Medicine, International Cancer Center, School of Pharmacy, Shenzhen University Medical School, Shenzhen 518060, China. Electronic address:
Lung cancer is the malignant tumor with the highest morbidity and mortality rate worldwide, of which non-small cell lung cancer (NSCLC) accounts for approximately 85%. KRAS mutations are one of the significant mechanisms underlying the occurrence, development, immune escape, and chemotherapy resistance of NSCLC. Two KRAS inhibitors are approved by FDA for the treatment of NSCLC in the past three years.
View Article and Find Full Text PDFTemporary Transvenous Pacing Performed in the Intensive Care Unit or in the Catheterization Laboratory.
Pacing Clin Electrophysiol
January 2025
Service de rythmologie cardiaque, Hôpital Cardiologique Louis Pradel, Hospices Civils de Lyon, Lyon, France.
Background: Temporary transvenous pacing (TTP) is a common procedure, predominantly performed in the catheterization laboratory (cath lab) because of presumed lower complication rate. This study aims to evaluate the efficacy and safety of TTP placement in the ICU compared to TTP placement in the cath lab.
Methods: This retrospective, real-life study included all patients requiring TTP in a tertiary care ICU between 2019 and 2022.
Inhibition of Unc-51-like-kinase is mitoprotective during infection in corneal epithelial cells.
mSphere
January 2025
Departments of Ophthalmology, The University of Texas Southwestern Medical Center, Dallas, Texas, USA.
(PA) is an opportunistic gram-negative pathogen that can infect the cornea, leading to permanent vision loss. Autophagy is a cannibalistic process that drives cytoplasmic components to the lysosome for degradation and/or recycling. Autophagy has been shown to play a key role in the removal of intracellular pathogens and, as such, is an important component of the innate immune response.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!