Targeting accuracy of an image guided gating system for stereotactic body radiotherapy

Stephen E. Tenn, Timothy D. Solberg, Paul M. Medin

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Recently, a commercial system capable of x-ray image guided patient positioning and respiratory gated delivery has become available. Here we describe the operational principles of this system and investigate its geometric targeting accuracy under controlled conditions. The system tracks breathing via infrared (IR) detection of reflective markers located on the patient's abdomen. Localization kilovoltage (kV) x-rays are triggered from within the gated delivery window portion of the breathing trace and after positioning, the tumour will cross the linac isocentre during gated delivery. We tested geometric accuracy of this system by localizing and delivering gated fields to a moving phantom. Effects of phantom speed, gating window location, timing errors and phantom rotations on positioning and gating accuracy were investigated. The system delivered gated fields to both a moving and static phantom with equal accuracy. The position of the gating window affects accuracy only to the extent that an asymmetric breathing motion could affect dose distribution within its boundaries. Positioning errors were found to be less then 0.5 ± 0.2 mm for phantom rotations up to 5°. We found and corrected a synchronization error caused by a faulty x-ray duration setting and detected a 60 ± 20 ms time delay in our linear accelerator.

Original languageEnglish (US)
Pages (from-to)5443-5462
Number of pages20
JournalPhysics in Medicine and Biology
Volume50
Issue number23
DOIs
StatePublished - Dec 7 2005

Fingerprint

Radiosurgery
Radiotherapy
positioning
radiation therapy
Respiration
breathing
geometric accuracy
X-Rays
X rays
delivery
Patient Positioning
Particle Accelerators
Linear accelerators
abdomen
Abdomen
x rays
Tumors
Time delay
Synchronization
linear accelerators

ASJC Scopus subject areas

  • Biomedical Engineering
  • Physics and Astronomy (miscellaneous)
  • Radiology Nuclear Medicine and imaging
  • Radiological and Ultrasound Technology

Cite this

Targeting accuracy of an image guided gating system for stereotactic body radiotherapy. / Tenn, Stephen E.; Solberg, Timothy D.; Medin, Paul M.

In: Physics in Medicine and Biology, Vol. 50, No. 23, 07.12.2005, p. 5443-5462.

Research output: Contribution to journalArticle

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