AffiliationNorth Western Medical Physics, Christie Hospital NHS Trust, Manchester M20 4BX, UK. firstname.lastname@example.org
MetadataShow full item record
AbstractThe Elekta Synergy is a radiotherapy treatment machine with integrated kilovoltage (kV) X-ray imaging system capable of producing cone beam CT (CBCT) images of the patient in the treatment position. The aim of this study is to assess the additional imaging dose. Cone beam CT dose index (CBDI) is introduced and measured inside standard CTDI phantoms for several sites (head: 100 kV, 38 mAs, lung: 120 kV, 152 mAs and pelvis: 130 kV, 456 mAs). The measured weighted doses were compared with thermoluminescent dosimeter (TLD) measurements at various locations in a Rando phantom and at patients' surfaces. The measured CBDIs in-air at the isocentre were 9.2 mGy 100 mAs(-1), 7.3 mGy 100 mAs(-1) and 5.3 mGy 100 mAs(-1) for 130 kV, 120 kV and 100 kV, respectively. The body phantom weighted CBDI were 5.5 mGy 100 mAs(-1) and 3.8 mGy 100 mAs(-1 )for 130 kV and 120 kV. The head phantom weighted CBDI was 4.3 mGy 100 mAs(-1) for 100 kV. The weighted doses for the Christie Hospital CBCT imaging techniques were 1.6 mGy, 6 mGy and 22 mGy for the head, lung and pelvis. The measured CBDIs were used to estimate the total effective dose for the Synergy system using the ImPACT CT Patient Dosimetry Calculator. Measured CBCT doses using the Christie Hospital protocols are low for head and lung scans whether compared with electronic portal imaging (EPI), commonly used for treatment verification, or single and multiple slice CT. For the pelvis, doses are similar to EPI but higher than CT. Repeated use of CBCT for treatment verification is likely and hence the total patient dose needs to be carefully considered. It is important to consider further development of low dose CBCT techniques to keep additional doses as low as reasonably practicable.
CitationImaging doses from the Elekta Synergy X-ray cone beam CT system. 2007, 80 (954):476-82 Br J Radiol
JournalThe British Journal of Radiology
- Dose assessment from an online kilovoltage imaging system in radiation therapy.
- Authors: Osei EK, Schaly B, Fleck A, Charland P, Barnett R
- Issue date: 2009 Mar
- Estimation of organ doses from kilovoltage cone-beam CT imaging used during radiotherapy patient position verification.
- Authors: Hyer DE, Hintenlang DE
- Issue date: 2010 Sep
- Phantom and in-vivo measurements of dose exposure by image-guided radiotherapy (IGRT): MV portal images vs. kV portal images vs. cone-beam CT.
- Authors: Walter C, Boda-Heggemann J, Wertz H, Loeb I, Rahn A, Lohr F, Wenz F
- Issue date: 2007 Dec
- Dosimetry of an in-line kilovoltage imaging system and implementation in treatment planning.
- Authors: Dzierma Y, Nuesken F, Otto W, Alaei P, Licht N, Rübe C
- Issue date: 2014 Mar 15
- Investigation of the radiation dose from cone-beam CT for image-guided radiotherapy: A comparison of methodologies.
- Authors: Buckley JG, Wilkinson D, Malaroda A, Metcalfe P
- Issue date: 2018 Jan