Highlights
- •Developed a QA system which determines mechanical, radiation, and imaging isocentres in three-dimensions.
- •The new system verifies the coincidence of isocentres in three-dimensions and visualized the coincidence.
- •The new system is semi-automatic utilizing a visual tracking system.
Abstract
Purpose
The objective of this work is to determine mechanical, radiation, and imaging isocentres
in three-dimensional (3D) coordinates and verifying coincidence of isocentres of passively
scattered proton beam using a visual tracking system (VTS) and an in-house developed
phantom named the Eagle.
Methods
The Eagle phantom consists of two modules: The first, named Eagle-head, is used for
determining 3D mechanical isocentre of gantry rotation. The second, named Eagle-body,
is used for determining 3D radiation and imaging isocentres. The Eagle-body has four
slots wherein radiochromic films were inserted for measuring the 3D radiation isocentre
and a metal bead was embedded in the centre of one cube to determine the imaging isocentre;
this was determined by analysing cone-beam computed tomography images of the cube.
Infrared reflective markers that can be tracked by VTS were attached to the Eagle
at predetermined locations. The tracked data were converted into 3D treatment room
coordinates. The developed method was compared with other methods to assess accuracy.
Results
The isocentres were determined in mm with respect to the laser isocentre. The mechanical,
radiation, and imaging isocentres were (−0.289, 0.189, 0.096), (−0.436, −0.217, 0.009),
and (0.134, 0.142, 0.103), respectively. When compared with other methods, the difference
in coordinates was (−0.033, −0.107, 0.014) and (0.003, 0.067, 0.039) for radiation
and imaging isocentres, respectively.
Conclusion
The developed system was found to be useful in providing fast and accurate measurements
of the three isocentres in the 3D treatment room coordinate system.
Keywords
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References
- Task Group 142 report: quality assurance of medical accelerators a.Med Phys. 2009; 36: 4197-4212
- Measurement of cone beam CT coincidence with megavoltage isocentre and image sharpness using the QUASAR™ Penta-Guide phantom.Phys Med Biol. 2008; 53: 5275
- Isocenter verification for linac-based stereotactic radiation therapy: review of principles and techniques.J Appl Clin Med Phys. 2011; 12: 185-195
- A procedure to determine the radiation isocenter size in a linear accelerator.Med Phys. 2004; 31: 1489-1493
- The linear accelerator mechanical and radiation isocentre assessment with an electronic portal imaging device (EPID).Austr Phys Eng Sci Med. 2004; 27: 111
- A system for stereotactic radiosurgery with a linear accelerator.Int J Radiat Oncol Biol Phys. 1988; 14: 373-381
- AAPM task group 224: comprehensive proton therapy machine quality assurance.Med Phys. 2019; 46: e678-e705
- Initial experience of patient-specific QA for wobbling and line-scanning proton therapy at samsung medical center.Prog Med Phys. 2019; 30: 14-21
- High-precision quality assurance of robotic couches with six degrees of freedom.Phys Med. 2018; 49: 28-33
- A procedure to determine the radiation isocenter size in a linear accelerator.Med Phys. 2004; 31: 1489-1493
- A study of vicon system positioning performance.Sensors (Basel). 2017; 17
Article info
Publication history
Published online: February 01, 2020
Accepted:
January 24,
2020
Received in revised form:
December 31,
2019
Received:
September 8,
2019
Identification
Copyright
© 2020 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
