Target dose study of effects of changes in the AAA Calculation resolution on Lung SABR plan

Lung SABR plan시 AAA의 Calculation resolution 변화에 의한 Target dose 영향 연구

  • Kim, Dae Il (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Son, Sang Jun (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Ahn, Bum Seok (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Jung, Chi Hoon (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Yoo, Suk Hyun (Department of Radiation Oncology, Seoul National University Hospital)
  • 김대일 (서울대학교병원 방사선종양학과) ;
  • 손상준 (서울대학교병원 방사선종양학과) ;
  • 안범석 (서울대학교병원 방사선종양학과) ;
  • 정치훈 (서울대학교병원 방사선종양학과) ;
  • 유숙현 (서울대학교병원 방사선종양학과)
  • Received : 2014.05.30
  • Accepted : 2014.12.02
  • Published : 2014.12.30

Abstract

Purpose : Changing the calculation grid of AAA in Lung SABR plan and to analyze the changes in target dose, and investigated the effects associated with it, and considered a suitable method of application. Materials and Methods : 4D CT image that was used to plan all been taken with Brilliance Big Bore CT (Philips, Netherlands) and in Lung SABR plan($Eclipse^{TM}$ ver10.0.42, Varian, the USA), use anisotropic analytic algorithm(AAA, ver.10, Varian Medical Systems, Palo Alto, CA, USA) and, was calculated by the calculation grid 1.0, 3.0, 5.0 mm in each Lung SABR plan. Results : Lung SABR plan of 10 cases are using each of 1.0 mm, 3.0 mm, 5.0 mm calculation grid, and in case of use a 1.0 mm calculation grid $V_{98}$. of the prescribed dose is about $99.5%{\pm}1.5%$, $D_{min}$ of the prescribed dose is about $92.5{\pm}1.5%$ and Homogeneity Index(HI) is $1.0489{\pm}0.0025$. In the case of use a 3.0 mm calculation grid $V_{98}$ dose of the prescribed dose is about $90{\pm}4.5%$, $D_{min}$ of the prescribed dose is about $87.5{\pm}3%$ and HI is about $1.07{\pm}1$. In the case of use a 5.0 mm calculation grid $V_{98}$ dose of the prescribed dose is about $63{\pm}15%$, $D_{min}$ of the prescribed dose is about $83{\pm}4%$ and HI is about $1.13{\pm}0.2$, respectively. Conclusion : The calculation grid of 1.0 mm is better improves the accuracy of dose calculation than using 3.0 mm and 5.0 mm, although calculation times increase in the case of smaller PTV relatively. As lung, spread relatively large and low density and small PTV, it is considered and good to use a calculation grid of 1.0 mm.

References

  1. Otto, K., Volumetric modulated arc therapy: IMRT in a single gantry arc. Med Phys, 2008. 35(1): 310-7. https://doi.org/10.1118/1.2818738
  2. Y. Nagata et al., "Stereotactic radiotherapy of primary lung cancer and other targets: Results of consultant meeting of the International Atomic Energy Agency," Int. J. Radiat. Oncol., Biol., Phys. 79, 660-669 (2011) https://doi.org/10.1016/j.ijrobp.2010.10.004
  3. R. Timmerman et al., " Optimizing dose and fractionation for stereotactic body radiation therapy. Normal tissue and tumor control effects with large dose per fraction,"Front. Radiat. Ther. Oncol. 40, 352- 365 (2007).
  4. R. W. Underberg et al., "Use of maximum intensity projections (MIP) for target volume generation in 4DCT scans for lung cancer,"Int. J. Radiat. Oncol., Biol., Phys. 63, 253-260(2005) https://doi.org/10.1016/j.ijrobp.2005.05.045
  5. Mesbahi, A., et al., Dosimetric properties of a flattening filter-free 6-MV photon beam: a Monte Carlo study. Radiat Med, 2007. 25(7): 315-24. https://doi.org/10.1007/s11604-007-0142-6
  6. K. Otto," Volumetric modulated arc therapy: IMRT in a single gantry arc,"Med. Phys. 35, 310-317 (2008). https://doi.org/10.1118/1.2818738
  7. A. Van Esch, L. Tillikainen, J. Pyykkonen, M. Tenhunen, H. Helminen, S. Siljamai, J.Alakuijala, M.Paiusco, M.Lori, and D. P.Huyskens," Testing of the analytical anisotropic algorithm for photon dose calculation,"Med. Phys. 33, 4130-4148 (2006). https://doi.org/10.1118/1.2358333
  8. C. M. Bragg, K. Wingate, and J. Conway, "Clinical implications of the anisotropic analytical algorithm for IMRT treatment planning and verification,"Radiother. Oncol. 86, 276-284 (2008). https://doi.org/10.1016/j.radonc.2008.01.011
  9. W. F Verbakel, J. P. Cuijpers, D. Hoffmans, M. Bieker, B. J. Slotman, and S. Senan, "Volumetric intensitymodulated arc therapy vs. conventional IMRT in headand- neck cancer: a comparative planning and dosimetric study,"Int. J. Radiat. Oncol., Biol., Phys. 74, 252-259 (2009). https://doi.org/10.1016/j.ijrobp.2008.12.033
  10. D. Hoffmans, and W. Verbakel, "Patient specific QA for 54 clinical RapidArc plans, a restrospective evaluation,"Radiother. Oncol. 92, S23 (2009).
  11. Chin Loon Ong, Johan P. Cuijpers, Suresh Senan, Ben J. Slotman and Wilko F. A. R. Verbakel" Impact of the calculation resolution of AAA for small fields and RapidArc treatment plans", American Association of Physicists in Medicine, 21-26, 4474 (2011)