A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup.

dc.contributor.author

Guan, Huaiqun

dc.contributor.author

Hammoud, Rabih

dc.contributor.author

Yin, Fang-Fang

dc.date.accessioned

2019-10-04T15:44:13Z

dc.date.available

2019-10-04T15:44:13Z

dc.date.issued

2009-10-06

dc.date.updated

2019-10-04T15:44:13Z

dc.description.abstract

A positioning QA procedure for Varian's 2D/2D (kV/MV) and 3D/3D (planCT/CBCT) matching was developed. The procedure was to check: (1) the coincidence of on-board imager (OBI), portal imager (PI), and cone beam CT (CBCT)'s isocenters (digital graticules) to a linac's isocenter (to a pre-specified accuracy); (2) that the positioning difference detected by 2D/2D (kV/MV) and 3D/3D(planCT/CBCT) matching can be reliably transferred to couch motion. A cube phantom with a 2 mm metal ball (bb) at the center was used. The bb was used to define the isocenter. Two additional bbs were placed on two phantom surfaces in order to define a spatial location of 1.5 cm anterior, 1.5 cm inferior, and 1.5 cm right from the isocenter. An axial scan of the phantom was acquired from a multislice CT simulator. The phantom was set at the linac's isocenter (lasers); either AP MV/R Lat kV images or CBCT images were taken for 2D/2D or 3D/3D matching, respectively. For 2D/2D, the accuracy of each device's isocenter was obtained by checking the distance between the central bb and the digital graticule. Then the central bb in orthogonal DRRs was manually moved to overlay to the off-axis bbs in kV/MV images. For 3D/3D, CBCT was first matched to planCT to check the isocenter difference between the two CTs. Manual shifts were then made by moving CBCT such that the point defined by the two off-axis bbs overlay to the central bb in planCT. (PlanCT can not be moved in the current version of OBI1.4.) The manual shifts were then applied to remotely move the couch. The room laser was used to check the accuracy of the couch movement. For Trilogy (or Ix-21) linacs, the coincidence of imager and linac's isocenter was better than 1 mm (or 1.5 mm). The couch shift accuracy was better than 2 mm.

dc.identifier.issn

1526-9914

dc.identifier.issn

1526-9914

dc.identifier.uri

https://hdl.handle.net/10161/19392

dc.language

eng

dc.relation.ispartof

Journal of applied clinical medical physics

dc.relation.isversionof

10.1120/jacmp.v10i4.2954

dc.subject

Humans

dc.subject

Imaging, Three-Dimensional

dc.subject

Radiotherapy Planning, Computer-Assisted

dc.subject

Lasers

dc.subject

Phantoms, Imaging

dc.subject

Computer Simulation

dc.subject

Image Processing, Computer-Assisted

dc.subject

Cone-Beam Computed Tomography

dc.subject

Patient Positioning

dc.title

A positioning QA procedure for 2D/2D (kV/MV) and 3D/3D (CT/CBCT) image matching for radiotherapy patient setup.

dc.type

Journal article

duke.contributor.orcid

Yin, Fang-Fang|0000-0002-2025-4740

pubs.begin-page

2954

pubs.issue

4

pubs.organisational-group

School of Medicine

pubs.organisational-group

Duke

pubs.organisational-group

Duke Kunshan University Faculty

pubs.organisational-group

Duke Kunshan University

pubs.organisational-group

Duke Cancer Institute

pubs.organisational-group

Institutes and Centers

pubs.organisational-group

Radiation Oncology

pubs.organisational-group

Clinical Science Departments

pubs.publication-status

Published

pubs.volume

10

Files