Cone beam CT (CBCT) in radiotherapy: Assessment of doses using a pragmatic setup in an international setting

Djukelic M 1 , Martin CJ 2 , Abuhaimed A 3 , Kron T 4 , Gros S 5 , Wood T 6 Show all authors , Pankowski P 7 , Ung NM 8 , Vassileva J 9 , Plazas MC 10 , Vostinic S 11 , Lazovic A 12 , Sá AC 13 , Nilsson I 14 , Koutrouli M 15 , Murugan L 16 , Fourie H 17 , Miadzvetski A 18 , Ameri BA 19 , Dumancic M 20 , Cheung AH 21 , Rahbi ZA 22 , Roussakis Y 23 , Shaaban HR 24 , Liang R 25 , Tomic N 26 , Salazar Correa DE 27 , Butler D 28 , Small W 29

Affiliations 

  • 1 Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands WA 6009, Australia; Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada. Electronic address: mario.djukelic@health.wa.gov.au
  • 2 Department of Clinical Physics and Bio-Engineering, University of Glasgow, Gartnavel Royal Hospital, Glasgow G12 0XH, UK; Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada. Electronic address: colinmartin1948@gmail.com
  • 3 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; King Abdulaziz City for Science and Technology (KACST), P.O. Box: 6086, Riyadh, Saudi Arabia. Electronic address: aabuhaimed@kacst.edu.sa
  • 4 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Physical Sciences, Peter MacCallum Cancer Centre, 305 Grattan Street, Melbourne VIC 3000, Australia; Centre for Medical Radiation Physics, University of Wollongong, Australia. Electronic address: Tomas.Kron@petermac.org
  • 5 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Loyola University Chicago, Stritch School of Medicine, Department of Radiation Oncology, Cardinal Bernardin Cancer Center, Maywood, IL 60153, USA. Electronic address: SEGROS@lumc.edu
  • 6 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Medical Physics Service, Queen's Centre, Castle Hill Hospital, Hull University Teaching Hospitals NHS Trust, Castle Road, Hull HU16 5JQ, UK. Electronic address: tim.wood3@nhs.net
  • 7 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Nuclear Physics and Radiation Safety, Faculty of Physics and Applied Informatics University of Lodz, Pomorska 149/153, 90-236 Lodz, Poland. Electronic address: piotr.pankowski@uni.lodz.pl
  • 8 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Clinical Oncology Unit, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia. Electronic address: nmung@ummc.edu.my
  • 9 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Radiation Protection of Patients Unit, International Atomic Energy Agency, Vienna International Centre, PO Box 100, 1400 Vienna, Austria. Electronic address: j.n.vassileva@gmail.com
  • 10 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Physics Department, Sciences Faculty, Universidad Nacional de Colombia, Bogotá, Colombia; Cancer Institute "Carlos Ardila Lülle", Santa Fe Foundation, Bogota, Colombia. Electronic address: mcplazasd@unal.edu.co
  • 11 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; National Cancer Research Centre, University of Belgrade, Belgrade, Serbia. Electronic address: svostinic@gmail.com
  • 12 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; National Cancer Research Centre, University of Belgrade, Belgrade, Serbia. Electronic address: anjalazovic@ymail.com
  • 13 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Centro de Ciências e Tecnologias Nucleares, Instituto Superior Técnico, Universidade de Lisboa, Campus Tecnológico e Nuclear, Estrada Nacional 10, Km 139.7, 2695-066 Bobadela LRS, Portugal; Center for Translational Health and Medical Biotechnology Research (TBIO)/Health Research Network (RISE-Health), School of Health, Polytechnic University of Porto, Rua Dr. António Bernardino de Almeida, 400, 4200-072 Porto, Portugal. Electronic address: anacravosa@ctn.tecnico.ulisboa.pt
  • 14 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Hematology, Skane University Hospital, Lund, Sweden; Medical Radiation Physics, Lund University Hospital, Lund, Sweden. Electronic address: Isabelle.M.Nilsson@skane.se
  • 15 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Medical Physics, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle, UK. Electronic address: maria.koutrouli@nhs.net
  • 16 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Radiation Oncology & Medical Physics, Rajiv Gandhi Government General Hospital and Madras Medical College, Chennai, India. Electronic address: lavanive04@gmail.com
  • 17 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Netcare Ltd, 76 Maude Street, Corner West Street, Sandton, South Africa. Electronic address: Hein.Fourie@netcare.co.za
  • 18 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; N.N. Alexandrov National Cancer Centre of Belarus, Liasny, Belarus. Electronic address: aliaksandr.miadzvetski@gmail.com
  • 19 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Federal Authority for Nuclear Regulation (FANR), Abu Dhabi, United Arab Emirates. Electronic address: buthaina.alameri@fanr.gov.ae
  • 20 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada. Electronic address: mirta.dumancic@mail.mcgill.ca
  • 21 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Hong Kong Baptist Hospital, 222 Waterloo Road, Hong Kong. Electronic address: ansonhycheung@hkbh.org.hk
  • 22 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Radiation Oncology, National Oncology Centre, Royal Hospital, Muscat, Oman. Electronic address: z.alra7bi@gmail.com
  • 23 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Department of Medical Physics, German Oncology Center, European University Cyprus, Limassol, Cyprus. Electronic address: Yiannis.Roussakis@goc.com.cy
  • 24 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Warith International Cancer Institute, Al-Horr Road, Karbala, Iraq. Electronic address: Hossam.Ragab1992@outlook.sa
  • 25 Mentorship programme, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Nuclear and Radiation Frontier Technology Research Center, China Institute for Radiation Protection, Taiyuan, Shanxi, PR China. Electronic address: liangruncheng@gmail.com
  • 26 Medical Physics Unit, Department of Oncology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada; Lady Davis Institute for Medical Research, Jewish General Hospital, Montreal, Quebec, Canada. Electronic address: ntomic@jgh.mcgill.ca
  • 27 Hospital Universitario Nacional de Colombia, Cl. 44 #59-75, Teusaquillo, Bogotá, Colombia; Los Cobos Medical Center, Ak. 9 #131a-40, Usaquén, Bogotá, Colombia. Electronic address: dsalazarco@unal.edu.co
  • 28 Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands WA 6009, Australia; Australian Radiation Protection and Nuclear Safety Agency, Primary Standards Dosimetry Laboratory, Yallambie, VIC 3085, Australia. Electronic address: Duncan.Butler@arpansa.gov.au
  • 29 Task Group 116 member, International Commission on Radiological Protection, 280 Slater Street, Ottawa, Ontario K1P 5S9, Canada; Loyola University Chicago, Stritch School of Medicine, Department of Radiation Oncology, Cardinal Bernardin Cancer Center, Maywood, IL 60153, USA. Electronic address: wmsmall@lumc.edu
Phys Med, 2025 Feb 21;131:104937.
PMID: 39985958 DOI: 10.1016/j.ejmp.2025.104937

Abstract

INTRODUCTION: The imaging modality kV CBCT on linear accelerators (linacs) is utilised to verify positioning and anatomy in cancer patients undergoing radiotherapy treatment. There is a need for optimisation of radiological protection in kV CBCT imaging protocols to avoid unnecessarily high exposures to normal tissues surrounding the target.

METHODS: A network of ICRP mentees from 23 countries were surveyed for available dosimetry equipment. Standardised measurements on CBCT linac imaging systems were conducted using a cone beam dose index (CBDI) devised as a straightforward measurement for wide beam doses. Measurements were made with (a) 100 mm ionisation chambers or (b) 0.6 cc Farmer ionisation chambers and cylindrical CT PMMA phantoms, and (c) an alternative setup of Farmer chambers and cubical phantoms comprised of slabs of water equivalent material readily available in radiotherapy centres. The measurements were compared with Monte Carlo (MC) simulations.

RESULTS: The survey showed limited availability for the reference setup using 100 mm chambers and CT phantoms. Correction factors were derived to convert normalised CBDI from alternative setups to the reference setup and are on average within 2% of MC simulations.

CONCLUSION: The slab phantom in combination with a Farmer chamber provides an alternative to quantify CBCT radiation dose indices from linac-based image-guided radiotherapy using materials accessible in most centres worldwide. A method is presented to use correction factors for Varian Truebeam linacs if traditional 100 mm chambers and cylindrical CT phantoms are not available. This will enable most radiotherapy centres across the world to engage in meaningful imaging dose measurement and optimisation.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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