Journal article
Patient dose and image quality from mega-voltage cone beam computed tomography imaging
Medical physics (Lancaster), v 34(2), pp 499-506
Feb 2007
PMID: 17388167
Featured in Collection : UN Sustainable Development Goals @ Drexel
Abstract
The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.
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Details
- Title
- Patient dose and image quality from mega-voltage cone beam computed tomography imaging
- Creators
- Olivier Gayou - Allegheny General HospitalDavid S Parda - Allegheny General HospitalMark Johnson - Allegheny General HospitalMoyed Miften - Allegheny General Hospital
- Publication Details
- Medical physics (Lancaster), v 34(2), pp 499-506
- Resource Type
- Journal article
- Language
- English
- Academic Unit
- Radiation Oncology (and Nuclear Medicine)
- Web of Science ID
- WOS:000244424200015
- Scopus ID
- 2-s2.0-33846624185
- Other Identifier
- 991019168339804721
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- Collaboration types
- Domestic collaboration
- Web of Science research areas
- Radiology, Nuclear Medicine & Medical Imaging