Comparison of using CBCT with CT Simulator for Radiation dose of Treatment Planning

CBCT와 Simulation CT를 이용한 치료계획의 선량비교

  • 김대영 (중앙대학교병원 방사선종양학과) ;
  • 최지원 (전주대학교 방사선학과) ;
  • 조정근 (전주대학교 방사선학과)
  • Published : 2009.12.28


The use of cone-beam computed tomography(CBCT) has been proposed for guiding the delivery of radiation therapy. A kilovoltage imaging system capable of radiography, fluoroscopy, and cone-beam computed tomography(CT) has been integrated with a medical linear accelerator. A standard clinical linear accelerator, operating in arc therapy mode, and an amorphous-silicon (a-Si) with an on-board electronic portal imager can be used to treat palliative patient and verify the patient's position prior to treatment. On-board CBCT images are used to generate patient geometric models to assist patient setup. The image data can also, potentially, be used for dose reconstruction in combination with the fluence maps from treatment plan. In this study, the accuracy of Hounsfield Units of CBCT images as well as the accuracy of dose calculations based on CBCT images of a phantom and compared the results with those of using CT simulator images. Phantom and patient studies were carried out to evaluate the achievable accuracy in using CBCT and CT stimulator for dose calculation. Relative electron density as a function of HU was obtained for both planning CT stimulator and CBCT using a Catphan-600 (The Phantom Laboratory, USA) calibration phantom. A clinical treatment planning system was employed for CT stimulator and CBCT based dose calculations and subsequent comparisons. The dosimetric consequence as the result of HU variation in CBCT was evaluated by comparing MU/cCy. The differences were about 2.7% (3-4MU/100cGy) in phantom and 2.5% (1-3MU/100cGy) in patients. The difference in HU values in Catphan was small. However, the magnitude of scatter and artifacts in CBCT images are affected by limitation of detector's FOV and patient's involuntary motions. CBCT images included scatters and artifacts due to In addition to guide the patient setup process, CBCT data acquired prior to the treatment be used to recalculate or verify the treatment plan based on the patient anatomy of the treatment area. And the CBCT has potential to become a very useful tool for on-line ART.)


Cone-beam Computed Tomography;Onboard Imaging System;Radiation Treatment Planning


  1. V. D. Jacob, The modern technology of radiation oncology, 1999.
  2. D. Letourneau, R. Wong, D. Moseley, et al., "Online planning and delivery technique for radiotherapy of spine metastases using cone-beam CT: Image quality and system performance", Int. J. Radiation Oncology Biol Phys., 67, pp.1229-1237, 2007.
  3. D. Jaffray, D. Drake, M. Moreau, et al., "A radiographic and tomographic imaging system integrated into a medical linear accelerator for localization of bone and soft-tissue targets", Int. J. Radiation Oncology Biol Phys., 45, pp.773-789, 1999.
  4. C. Wu, R. Jeraj, G. Olivera, et al., "Reoptimization in adaptive radiothrapy", Phy. Med. Biol., 47, pp. 3181-3195, 2002.
  5. S. Yoo, F-F. Yin, "Dosimetric feasibility of cone-beam CT-based treatment planning compared to CT-based treatment planning", Int. J. Radiation Oncology Biol Phys., 66, pp.1553-1561, 2006.
  6. Y. Yang, E. Schreibmann, T. Li, C. Wang, L. Xing., "Evaluation of on-board kV cone beam CT(CBCT)-based dose calculation", Phy. Med. Biol., 52, pp.685-705, 2007.
  7. G. Hounsfield, "Computerized transverse axial scanning(tomography) 1. Description of system", Brit. J. Radiol., 46, pp.1016-1022, 1973.
  8. H. Hu, HD. He, WD. Foley, SH. Fox., "Four multidetector-row helical CT : image quality and volume coverage speed", Radiology, 215, pp.55-62, 2000.
  9. SJ. Thomas, "Relative electron density calibration of CT scanner for radiotherapy treatment planning", Br. J. Radiol.,. 72, pp.781-786, 1999.
  10. RA. Rob, "High-speed three-dimensional computed tomography and multi-dimensional display on the heart, lung, and circulation", In:Fullerton GD, Zagzebski JA(eds.), AAPM monography No.6., The American Institute of Physics. Medical Physics of CT and ultrasound. New York, pp.656-702 1980.
  11. 최용석, 김규태, 황의환, "Cone beam형 전산화단층영상의 원리", 대한구강악안면방사선학회지, 36 권, pp.123-129, 2006.
  12. J. Battista, W. Rider, Dyk. Van, "Computed tomography for radiotherapy planning", Int. J. Radiat Oncol Biol. Phys., 6, pp.99-107, 1980.
  13. C. Constantinou, J. Harrington, L. DeWerd,, "An electron density calibration phantom for CT-based treatment planning computers", Med. Phys., 19, pp.325-327, 1991.