Related Experiment Video
Updated: Feb 6, 2026
05:01
A Detailed Protocol for Physiological Parameters Acquisition and Analysis in Neurosurgical Critical Patients
Published on: October 17, 2017
7.5K
Trajectory log file sensitivity: A critical analysis using DVH and EPID
Wui Ann Woon1,2, Paul B Ravindran2,3, Piyasiri Ekayanake2
1Department of Radiation Oncology, The Brunei Cancer Center, Bandar Seri Begawan BG3122, Brunei Darussalam.
Summary
Trajectory log files effectively detect multileaf collimator (MLC) positioning errors in radiation therapy. This quality assurance method correlates well with dose errors, improving treatment accuracy.
Area of Science:
- Medical Physics
- Radiation Oncology
- Quality Assurance
Background:
- Quality assurance in radiation therapy is crucial for patient safety.
- Trajectory log files offer a novel method for monitoring treatment delivery accuracy.
- Electronic portal imaging device (EPID) measurements are a standard for verification.
Purpose of the Study:
- To evaluate the sensitivity of trajectory log file analysis in detecting MLC and gantry positioning errors.
- To compare log file-based quality assurance with EPID measurements using the 3%/3mm criteria.
- To analyze the correlation between gamma passing rates and dose errors.
Main Methods:
- An in-house program modified treatment plans using log file data to recalculate dose distributions.
- Recalculated dose-volume histograms (DVHs) were compared to original DVHs.
- Differences in DVH were compared with EPID dosimetry.
Main Results:
- A strong positive linear relationship was observed between MLC positioning errors and dose errors for IMRT and VMAT plans.
- Gantry positioning errors had minimal impact on VMAT delivery.
- A significant positive correlation was found between VMAT gamma passing rates (3%/3mm) and mean DVH dose error (r=0.59, P<0.001).
Conclusions:
- Trajectory log files are sensitive to systematic MLC errors and random errors in dose delivery.
- The study successfully analyzed the correlation between gamma passing rates and DVH metrics.
- Log file analysis provides a valuable tool for quality assurance in radiation therapy.
Related Concept Videos
01:26Orthogonal Trajectories
70
Orthogonal trajectories describe the geometric relationship between two families of curves that intersect each other at right angles. One illustrative case involves a family of parabolas that open sideways along the x-axis. These curves share a common shape but differ by a scaling parameter, resulting in a set of curves that all pass through the origin and widen at different rates.Determining Orthogonal TrajectoriesTo identify the orthogonal trajectories for these parabolas, the first step...
70
01:19The Mantel-Cox Log-Rank Test
1.1K
The Mantel-Cox log-rank test is a widely used statistical method for comparing the survival distributions of two groups. It tests whether a statistically significant difference exists in survival times between the groups without assuming a specific distribution for the survival data, making it a non-parametric test. This flexibility makes the log-rank test particularly valuable in medical research and other fields where the timing of an event, such as death or disease recurrence, is of...
1.1K
01:16Critical Region, Critical Values and Significance Level
13.4K
The critical region, critical value, and significance level are interdependent concepts crucial in hypothesis testing.
In hypothesis testing, a sample statistic is converted to a test statistic using z, t, or chi-square distribution. A critical region is an area under the curve in probability distributions demarcated by the critical value. When the test statistic falls in this region, it suggests that the null hypothesis must be rejected. As this region contains all those values of the...
In hypothesis testing, a sample statistic is converted to a test statistic using z, t, or chi-square distribution. A critical region is an area under the curve in probability distributions demarcated by the critical value. When the test statistic falls in this region, it suggests that the null hypothesis must be rejected. As this region contains all those values of the...
13.4K
01:31Critical Values
10.4K
A critical value is a definite value obtained from a particular probability distribution at a predecided confidence level (or a predecided significance level) for a given population parameter. The critical value provides demarcation that separates the sample statistics that are likely to occur from the ones that are unlikely to occur based on the given probability distribution and the population parameter to be estimated. The critical value for normal distribution is obtained from the z...
10.4K
01:24Critical Thinking I
5.2K
Critical thinking helps decision-making and allows nurses to recognize barriers to success and find solutions to possible issues. It helps to brainstorm and implement ideas to achieve goals. Critical thinking helps acknowledge and state workflow inefficiencies while improving management techniques. Nurses understand the value of critical thinking and look for fellow nurses with critical thinking skills to upgrade their professional standards. Critical thinking can advance a nurse's career...
5.2K
01:25Critical Thinking II
4.7K
Critical thinking is a cognitive process with several attributes. The attributes of critical thinking include the following:
4.7K