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Comparison of verification accuracy and radiation dose between megavoltage CT and kilovoltage cone-beam CT

  • Vincent W.C. Wu (a1), M.L. Ho (a1), L.Y. Yuen (a1), K.L. Li (a1), N.F. Lai (a1), Y.C. Tsang (a1), W.Y. Lee (a2) and G. Chiu (a2)...


Purpose: This study evaluated the difference in verification performance and organ doses between megavoltage computed tomography (MVCT) and kilovoltage cone-beam computed tomography (kV CBCT).

Methods: Anthropomorphic phantoms of head-and-neck (H&N) and pelvic regions were scanned by the computed tomography–simulator. A common reference standard setup position for each phantom was determined. Markings of known deviations from the standard position in the lateral, longitudinal and yaw displacements were made on the phantoms. The verifications by kV CBCT and MVCT were conducted in the linear accelerator and helical tomotherapy treatment unit respectively. The phantoms were then shifted in steps according to the assigned different degree of positional deviations. The discrepancy between the detected data and the known data (δD) indicated the detection error of the verification system. Thermoluminescent dosimeters were used for dose measurements of kV CBCT and MVCT.

Results: δD of the lateral translations and yaw rotation in kV CBCT of the H&N region were lower than MVCT. There were no differences in the error detection along longitudinal direction between the two verification methods. For H&N, the mean doses of the various organs were significantly lower in kV CBCT except the skin. For the pelvis, MVCT delivered significantly higher mean dose to the prostate and femoral heads.


Corresponding author

Correspondence to: Vincent W.C. Wu, Department of Health Technology and Informatics, Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong. E-mail:


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Mangar, SA, Huddart, RA, Parker, CC, Dearnaley, DP, Khoo, VS, Horwich, A. Technological advances in radiotherapy for the treatment of localised prostate cancer. Eur J Cancer 2005; 41: 908921.
Kam, MK, Teo, PM, Chau, RM, Cheung, KY, Choi, PH, Kwan, WH, Leung, SF, Zee, B, Chan, AT. Treatment of nasopharyngeal carcinoma with intensity-modulated radiotherapy: the Hong Kong experience. Int J Radiat Oncol Biol Phys 2004; 60: 14401450.
Johansson, J, Blomquist, E, Montelius, A, Isacsson, U, Glimelius, B. Potential outcomes of modalities and techniques in radiotherapy for patients with hypopharyngeal carcinoma. Radiother Oncol 2004; 72: 129138.
Mackie, TR, Kapatoes, J, Ruchala, K, Lu, W, Wu, C, Olivera, G, Forrest, L, Tome, W, Welsh, J, Jeraj, R, Harari, P, Reckwerdt, P, Paliwal, B, Ritter, M, Keller, H, Fowler, J, Mehta, M. Image guidance for precise conformal radiotherapy. Int J Radiat Oncol Biol Phys 2003; 56: 89105.
Schubert, LK, Westerly, DC, Tomé, WA, Mehta, MP, Soisson, ET, Mackie, TR, Ritter, MA, Khuntia, D, Harari, PM, Paliwal, BR. A comprehensive assessment by tumor site of patient setup using daily MVCT imaging from more than 3,800 helical tomotherapy treatments. Int J Radiat Oncol Biol Phys 2009; 73: 12601269.
Borst, GR, Sonke, JJ, Betgen, A, Remeijer, P, van Herk, M, Lebesque, JV. Kilo-voltage cone-beam computed tomography setup measurements for lung cancer patients; first clinical results and comparison with electronic portal-imaging device. Int J Radiat Oncol Biol Phys 2007; 68: 555561.
Hong, TS, Welsh, JS, Ritter, MA, Harari, PM, Jaradat, H, Mackie, TR, Mehta, MP. Megavoltage computed tomography: an emerging tool for image-guided radiotherapy. Am J Clin Oncol 2007; 30: 617623.
Santanam, L, Esthappan, J, Mutic, S, Klein, EE, Goddu, SM, Chaudhari, S, Wahab, S, El Naqa, IM, Low, DA, Grigsby, PW. Estimation of setup uncertainty using planar and MVCT imaging for gynecologic malignancies. Int J Radiat Oncol Biol Phys 2008; 71: 15111517.
Ezzell, GA, Galvin, JM, Low, D, Palta, JR, Rosen, I, Sharpe, MB, Xia, P, Xiao, Y, Xing, L, Yu, CX; IMRT subcommitte; AAPM Radiation Therapy committee. Guidance document on delivery, treatment planning, and clinical implementation of IMRT: report of the IMRT subcommittee of the AAPM Radiation Therapy Committee. Med Phys 2003; 30: 20892115.
Walter, C, Boda-Heggemann, J, Wertz, H, Loeb, I, Rahn, A, Lohr, F, Wenz, F. Phantom and in-vivo measurements of dose exposure by image-guided radiotherapy (IGRT): MV portal images vs. kV portal images vs. cone-beam CT. Radiother Oncol 2007; 85: 418423.
Zhu, L, Starman, J, Fahrig, R. An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone-Beam CT. Int J Biomed Imaging 2008; 2008:242841.
Renström, J. Evaluation of the Elekta Synergy concept for patient positioning in image guided radiotherapy. Lund University, Lund: Medical Radiation Physics, 2005.
Shah, AP, Langen, KM, Ruchala, KJ, Cox, A, Kupelian, PA, Meeks, SL. Patient dose from megavoltage computed tomography imaging. Int J Radiat Oncol Biol Phys 2008; 70: 15791587.



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