Related Experiment Video
Updated: Jun 30, 2026
09:14
Image-guided Convection-enhanced Delivery into Agarose Gel Models of the Brain
Published on: May 14, 2014
11.4K
Air inflow into vacuum-type immobilization devices impacts setup errors.
Fumiyasu Matsubayashi1, Tatsuya Kamima2, Yasushi Ito2
1Radiation Oncology Department, Cancer Institute Hospital, Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-Ku, Tokyo, 135-8550, Japan. fumiyasu.matsubayashi@jfcr.or.jp.
Radiological Physics and Technology
|June 18, 2024
Summary
Weekly deflation of vacuum-type immobilization devices (VIDs) significantly reduces setup errors in head and neck cancer radiotherapy. This improves patient setup reproducibility by maintaining consistent pressure within the VIDs.
Area of Science:
- Medical Physics
- Radiation Oncology
- Biomedical Engineering
Background:
- Vacuum-type immobilization devices (VIDs) are crucial for patient positioning in radiotherapy.
- Maintaining consistent pressure within VIDs is essential for accurate patient setup.
- Air inflow can lead to pressure fluctuations, potentially increasing setup errors.
Purpose of the Study:
- To investigate the effect of air inflow into VIDs on setup errors during radiotherapy.
- To compare setup errors between patients with weekly deflated VIDs and those with non-deflated VIDs.
- To assess the relationship between VID pressure changes and setup accuracy.
Main Methods:
- Seventy head and neck cancer patients were divided into two groups: weekly VIDs deflation (Group V) and no deflation (Group N).
- Systematic errors (Σ) and random errors (σ) were calculated for each patient.
- Overall means (μ) and standard deviations (SDoverall) of setup errors were compared between groups.
- Temporary pressure changes within VIDs were monitored.
Main Results:
- While overall means (μ) were similar (within 0.20 mm and 0.2°), SDoverall significantly differed between groups.
- Group V showed lower SDoverall (0.58°) compared to Group N (0.87°) in the Roll axes.
- Systematic (Σ) and random (σ) errors were consistently lower across all axes in Group V.
- Weekly deflation maintained VID pressure around -20 kPa, whereas non-deflated VIDs pressure increased to -5 kPa.
Conclusions:
- Effective pressure control in VIDs through weekly deflation reduces patient-to-patient variation.
- Regular VIDs deflation enhances setup reproducibility for individual patients.
- This leads to smaller variations in overall setup errors, improving treatment accuracy.
Related Concept Videos
01:29Mechanical Ventilation I: Indication and Settings
Mechanical ventilation is a life-saving technique for managing acute respiratory failure and other respiratory complications. The process involves using a machine known as a ventilator to supply oxygen to the lungs and assist in removing carbon dioxide. It serves as a bridge to long-term mechanical ventilation or a temporary measure until ventilatory support is discontinued. The ventilator can maintain this function for a prolonged period, providing critical support for patients until they can...
01:23Mechanical Ventilation II: Invasive Ventilation
Ventilators are essential medical equipment used to aid patients with respiratory difficulties. Their primary function is to assist or replace spontaneous breathing by providing mechanical ventilation. There are two general classes of mechanical ventilators: negative-pressure and positive-pressure ventilators.
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
Negative-Pressure Ventilators
Negative-pressure ventilators create a vacuum around the chest or body to draw air into the lungs, simulating breathing. This method does not require an...
01:24Static, Stagnation, Dynamic and Total Pressure
The concept of static, stagnation, dynamic, and total pressure is fundamental in fluid dynamics, often explained using Bernoulli's equation:
01:27Laminar Flow
Laminar flow represents a smooth, orderly fluid motion where particles move along parallel paths, resulting in minimal mixing between layers. Streamlined particle paths characterize this flow regime and occur under conditions where viscous forces dominate over inertial forces. The distinction between laminar, transitional, and turbulent flow is primarily determined by the Reynolds number, a dimensionless quantity calculated as:
01:28Pipe Flowrate Measurement
In pipe flow measurement, orifice, nozzle, and Venturi meters are commonly used to determine fluid flowrates by constricting the flow area, which increases fluid velocity and reduces pressure. This pressure difference, governed by Bernoulli's principle and adjusted for real-world conditions, is essential for calculating flowrate. Each meter type is suited to specific applications based on accuracy, efficiency, and compatibility with various flow conditions.
The orifice meter is a simple,...
The orifice meter is a simple,...
01:26General External Flow Characteristics
The study of external flow is essential for creating structures and objects that interact efficiently and safely with moving fluids, such as air or water. When a body is immersed in a flowing fluid, it experiences two primary forces: drag, which opposes motion along the flow direction, and lift, which acts perpendicular to the flow. The shape, size, and orientation of the object influence these forces.Streamlined and Blunt Bodies in External FlowObjects in fluid flow are classified as...