Abstract
Cone beam computed tomography (CBCT) is used widely for the precise and accurate patient set up needed during radiation therapy, notably for hypo fractionated treatments, such as intensity modulated radiation therapy and stereotactic radiation therapy. Reported doses associated with CBCT indicate the potential to approach radiation tolerance levels for some critical organs. However while some manufacturers state the CBCT dose for each standard protocol, currently there are no standard or recognised protocols for CBCT dosimetry. This study has applied wide beam computed tomography dosimetry approaches as reported by the International Atomic Energy Agency and the American Association of Physicists in Medicine to investigate dosimetry for the Varian Trilogy linear accelerator with on-board imager v1.5. Three detection methods were used including (i) the use of both 100 mm and 300 mm pencil ionisation chambers, (ii) a 0.6 cm3 ionisation chamber and (iii) gafchromic film. Measurements were performed using custom built 45 cm long PMMA phantoms as well as standard 15 cm long phantoms for both head and body simulation. The results showed good agreement between each other detector system (within 3 %). The measured CBCT dose for the above methods showed a large difference to the dose stated by Varian, with the measured dose being 40 % over the stated dose for the standard head protocol. This shows the importance of independently verifying the stated dose given by the vendor for standard procedures.
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References
Thilmann C (2006) Correction of patient positioning errors based on in-line cone beam CTs: clinical implementation and first experiences. Radiat Oncol 1:16
Dietrich L, Jetter S, Tucking T, Nill S, Oelfke U (2006) Linac-integrated 4D cone beam CT: first experimental results. Phys Med Biol 51(11):2939
Oldham M (2005) Cone-beam-CT guided radiation therapy: a model for on-line application. Radiother Oncol 75(3):271.E1–271.E8
Martin JM, Bayley A, Bristow R, Chung P, Gospodarowicz M, Menard C, Milosevic M, Rosewall T, Warde PR, Catton CN (2009) Image guided dose escalated prostate radiotherapy: still room to improve. Int J Radiat Oncol 4(65):50
Karam SD, Horne ZD, Hong RL, McRae D, Duhanel D, Nasr NM (2013) Dose escalation with stereotactic body radiation therapy boost for locally advanced non small cell lung cancer. Int J Radiat Oncol 8(1):179
Islam M, Purdie T, Norrlinger B, Alasti H, Moseley D, Sharpe M, Siewerden J, Jaffray D (2006) Patient dose from kilovoltage cone beam computed tomography imaging in radiation therapy. Med Phys 33(6):1573–1582
Travis LB, Boice Jr JD, Allan JM, Applegate KE, Constine LS, Gilbert ES, Kennedy AR, Ng AK-M, Pui C-H, Purdy JA, Xu GX, Yahalom J (2011) NCRP Report No. 170: second primary cancers and cardiovascular disease after radiation therapy, National Council on Radiation Protection and Measurements, Bethesda
Kim D, Chung W, Yoon M (2013) Imaging doses and secondary cancer risk from kilovoltage cone-beam CT in radiation therapy. Health Phys 104:499–503
Spezi E, Downes P, Jarvis R, Radu E, Staffurth J (2012) Patient-specific three dimensional concomitant dose from cone beam computed tomography exposure in image-guided radiotherapy. Int J Radiat Oncol 83(1):419–426
Horner K, Islam M, Flygare L, Tsiklakis K, Whaites E (2009) Basic principles for use of dental cone beam computed tomography: consensus guidelines of the European Academy of Dental and Maxillofacial Radiology. Dento Maxillo Facial Radiol 38(4):187–195
Pauwels R et al (2012) Dose distribution for dental cone beam CT and its implication for defining a dose index. Dento Maxillo Fac Radiol 41(7):583–593
Kim SS, Samei YE, Yoshizumi FF (2011) Computed tomography dose index and dose length product for cone-beam CT: Monte Carlo simulations. J Appl Clin Med Phys 12(2):84–95
Sykes JR, Lindsay R, Iball G, Thwaites DI (2013) Dosimetry of CBCT: methods, doses and clinical consequences, in IOP
International Atomic Energy Agency (2011) IAEA human health reports no. 5: Status of computed tomography dosimetry for wide cone beam scanners. IAEA, Vienna
American Association of Medical Physics (2010) Report of AAPM Task Group 111: the future of CT dosimetry. AAPM, College Park
Kan MW, Leung LH, Wong W, Lam N (2008) Radiation dose from cone beam computed tomography for image-guided radiation therapy. Int J Radiat Oncol 70(1):272–279
Kim S, Yoshizumi TT, Toncheva G, Yoo S, Yin F-F (2008) Comparison of radiation doses between cone beam CT and multi detector CT: TLD measurements. Radiat Prot Dosim 132(3):339–345
Kim S, Yoshizumi TT, Toncheva G, Frush DP, Yin F-F (2010) Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and monte carlo simulations. Radiat Prot Dosim 138(3):257–263
Giaddui T, Cui Y, Galvin J, Yu Y, Xiao Y (2013) Comparative dose evaluations between XVI and OBI cone beam CT systems using Gafchromic XRQA2 film and nanoDot optical stimulated luminescence dosimeters. Med Phys 40(6):062102
Tomic N, Devic S, Deblois F, Seuntjens J (2010) Reference radiochromic film dosimetry in kilovoltage photon beams during CBCT image acquisition. Med Phys 37(3):1083–1092
Ding G, Coffey C (2009) Radiation dose from kilovoltage cone beam computed tomography in an image-guided radiotherapy procedure. Int J Radiat Oncol 73(2):610–617
International Atomic Energy Agency (2012) Quality assurance programme for computed tomography: diagnostic and therapy applications. IAEA, Vienna
International Commission of Radiological Units (2012) ICRU Report No. 87: Radiation dose and image-quality assessment in computed tomography. Oxford University Press, Oxford
International Atomic Energy Agency (2007) Technical Reports Series No. 457 dosimetry in diagnostic radiology: an international code of practice. IAEA, Vienna
Boone J (2007) The trouble with CTDI100. Med Phys 34(4):1364–1371
Varian Medical Systems (2012) Dose in CBCT—OBI advanced imaging On-Board Imager kV imaging systems v1.4 and v1.5. Varian Medical Systems, Palo Alto
International Electrotechnical Commission (2011) IEC 61217 radiotherapy equipment—co-ordinates, movements and scales, International Electrotechnical Commission
Palm A, Nilsson E, Hernsdorf L (2010) Absorbed dose and dase rate using the Varian OBI 1.3 and 1.4 CBCT system. J Appl Clin Med Phys 11(1):229–240
American Association of Medical Physics (2011) AAPM Report 204: size-specific dose estimates (SSDE) in pediatric and adult body CT examinations. American Association of Physicist in Medicine, College Park
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Hu, N., McLean, D. Measurement of radiotherapy CBCT dose in a phantom using different methods. Australas Phys Eng Sci Med 37, 779–789 (2014). https://doi.org/10.1007/s13246-014-0301-x
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DOI: https://doi.org/10.1007/s13246-014-0301-x