한국의학물리학회지:의학물리 (Progress in Medical Physics)

  • 제25권4호
  • /
  • Pages.288-297
  • /
  • 2014
  • /
  • 2508-4445(pISSN)
  • /
  • 2508-4453(eISSN)
한국의학물리학회 (Korean Society of Medical Physics)
권호 표지
DOI QR코드

DOI QR Code

Use of Flattening Filter Free Photon Beams for Off-axis Targets in Conformal Arc Stereotactic Body Radiation Therapy

  • 투고 : 2014.11.18
  • 심사 : 2014.12.14
  • 발행 : 2014.12.30
PDF 다운로드
⟨ 이전 논문 다음 논문 ⟩

초록

Dynamic conformal arc therapy (DCAT) and flattening-filter-free (FFF) beams are commonly adopted for efficient conformal dose delivery in stereotactic body radiation therapy (SBRT). Off-axis geometry (OAG) may be necessary to obtain full gantry rotation without collision, which has been shown to be beneficial for peripheral targets using flattened beams. In this study dose distributions in OAG using FFF were evaluated and the effect of mechanical rotation induced uncertainty was investigated. For the lateral target, OAG evaluation, sphere targets (2, 4, and 6 cm diameter) were placed at three locations (central axis, 3 cm off-axis, and 6 cm off-axis) in a representative patient CT set. For each target, DCAT plans under the same objective were obtained for 6X, 6FFF, 10X, and 10FFF. The parameters used to evaluate the quality of the plans were homogeneity index (HI), conformality indices (CI), and beam on time (BOT). Next, the mechanical rotation induced uncertainty was evaluated using five SBRT patient plans that were randomly selected from a group of patients with laterally located tumors. For each of the five cases, a plan was generated using OAG and CAG with the same prescription and coverage. Each was replanned to account for one degree collimator/couch rotation errors during delivery. Prescription isodose coverage, CI, and lung dose were evaluated. HI and CI values for the lateral target, OAG evaluation were similar for flattened and unflattened beams; however, 6FFF provided slightly better values than 10FFF in OAG. For all plans the HI and CI were acceptable with the maximum difference between flattened and unflattend beams being 0.1. FFF beams showed better conformality than flattened beams for low doses and small targets. Variation due to rotational error for isodose coverage, CI, and lung dose was generally smaller for CAG compared to OAG, with some of these comparisons reaching statistical significance. However, the variations in dose distributions for either treatment technique were small and may not be clinically significant. FFF beams showed acceptable dose distributions in OAG. Although 10FFF provides more dramatic BOT reduction, it generally provides less favorable dosimetric indices compared to 6FFF in OAG. Mechanical uncertainty in collimator and couch rotation had an increased effect for OAG compared to CAG; however, the variations in dose distributions for either treatment technique were minimal.

키워드

참고문헌

  1. Timmerman R, Galvin J, Michalski J, Straube W, Ibbott G, Martin E, Abdulrahman R, Swann S, Fowler J, Choy H: Accreditation and quality assurance for Radiation Therapy Oncology Group: Multicenter clinical trials using Stereotactic Body Radiation Therapy in lung cancer. Acta Oncol 2006, 45(7):779-786. https://doi.org/10.1080/02841860600902213
  2. Takeda A, Kunieda E, Sanuki N, Ohashi T, Oku Y, Sudo Y, Iwashita H, Ooka Y, Aoki Y, Shigematsu N, Kubo A: Dose distribution analysis in stereotactic body radiotherapy using dynamic conformal multiple arc therapy. Int J Radiat Oncol Biol Phys 2009, 74(2):363-369. https://doi.org/10.1016/j.ijrobp.2008.08.012
  3. Cashmore J: The characterization of unflattened photon beams from a 6 MV linear accelerator. Phys Med Biol 2008, 53(7):1933-1946. https://doi.org/10.1088/0031-9155/53/7/009
  4. Stathakis S, Esquivel C, Gutierrez A, Buckey CR, Papanikolaou N: Treatment planning and delivery of IMRT using 6 and 18MV photon beams without flattening filter. Appl Radiat Isot 2009, 67(9):1629-1637. https://doi.org/10.1016/j.apradiso.2009.03.014
  5. Georg D, Knoos T, McClean B: Current status and future perspective of flattening filter free photon beams. Med Phys 2011, 38(3):1280-1293. https://doi.org/10.1118/1.3554643
  6. Kragl G, Baier F, Lutz S, Albrich D, Dalaryd M, Kroupa B, Wiezorek T, Knoos T, Georg D: Flattening filter free beams in SBRT and IMRT: dosimetric assessment of peripheral doses. Z Med Phys 2011, 21(2):91-101. https://doi.org/10.1016/j.zemedi.2010.07.003
  7. Thomas EM, Popple RA, Prendergast BM, Clark GM, Dobelbower MC, Fiveash JB: Effects of flattening filter-free and volumetric-modulated arc therapy delivery on treatment efficiency. J Appl Clin Med Phys 2013, 14(6):4328.
  8. Kretschmer M, Sabatino M, Blechschmidt A, Heyden S, Grunberg B, Wurschmidt F: The impact of flattening-filter-free beam technology on 3D conformal RT. Radiat Oncol 2013, 8:133. https://doi.org/10.1186/1748-717X-8-133
  9. Ross CC, Kim JJ, Chen ZJ, Grew DJ, Chang BW, Decker RH: A novel modified dynamic conformal arc technique for treatment of peripheral lung tumors using stereotactic body radiation therapy. Pract Radiat Oncol 2011, 1(2):126-134. https://doi.org/10.1016/j.prro.2010.11.002
  10. Shi C, Tazi A, Fang DX, Iannuzzi C: Implementation and evaluation of modified dynamic conformal arc (MDCA) technique for lung SBRT patients following RTOG protocols. Med Dosim 2013, 38(3):287-290. https://doi.org/10.1016/j.meddos.2013.02.010
  11. Kragl G, af Wetterstedt S, Knausl B, Lind M, McCavana P, Knoos T, McClean B, Georg D: Dosimetric characteristics of 6 and 10MV unflattened photon beams. Radiother Oncol 2009, 93(1):141-146. https://doi.org/10.1016/j.radonc.2009.06.008
  12. Ponisch F, Titt U, Vassiliev ON, Kry SF, Mohan R: Properties of unflattened photon beams shaped by a multileaf collimator. Med Phys 2006, 33(6):1738-1746. https://doi.org/10.1118/1.2201149
  13. Yarahmadi M, Allahverdi M, Nedaie HA, Asnaashari K, Vaezzadeh SA, Sauer OA: Improvement of the penumbra for small radiosurgical fields using flattening filter free low megavoltage beams. Z Med Phys 2013, 23(4):291-299. https://doi.org/10.1016/j.zemedi.2013.03.011
  14. Kim S: UF image-guided stereotactic body radiation therapy (IGSBRT) program for lung treatment using Elekta Synergy. In IFMBE Proceedings. Edited by Magjarevic R. Springer; 2007.
  15. Olivier K, Chung H, Jin H, Yang H, Kim S: Intra-Fraction Patient Displacement During Image Guided Stereotactic Body Radiation Therapy (IGSBRT) for Lung Treatment. Int J Radiat Oncol Biol Phys 2006, 66(3):S489.
  16. Khoo VS, Oldham M, Adams EJ, Bedford JL, Webb S, Brada M: Comparison of intensity-modulated tomotherapy with stereotactically guided conformal radiotherapy for brain tumors. Int J Radiat Oncol Biol Phys 1999, 45(2):415-425.
  17. Murphy MJ, Chang S, Gibbs I, Le QT, Martin D, Kim D: Image-guided radiosurgery in the treatment of spinal metastases. Neurosurg Focus 2001, 11(6):e6.
  18. Josipovic M, Persson GF, Logadottir A, Smulders B, Westmann G, Bangsgaard JP: Translational and rotational intra- and inter-fractional errors in patient and target position during a short course of frameless stereotactic body radiotherapy. Acta Oncol 2012, 51(5):610-617. https://doi.org/10.3109/0284186X.2011.626448
  19. ACR-ASTRO practice guideline for the performance of stereotactic body radiation therapy. Practice Guidelines and Technical Standards. Reston, VA: American College of Radiology; 2009.

피인용 문헌

  1. Improving Delivery Accuracy of Stereotactic Body Radiotherapy to a Moving Tumor Using Simplified Volumetric Modulated Arc Therapy vol.11, pp.6, 2016, https://doi.org/10.1371/journal.pone.0158053
  2. Improvement of off-axis SABR plan verification results by using adapted dose reconstruction algorithms for the Octavius 4D system vol.45, pp.4, 2018, https://doi.org/10.1002/mp.12805
  3. Delivery efficiency and susceptibility to setup uncertainties of flattening filter free lung SBRT: influence of isocentre geometry and treatment modality vol.63, pp.20, 2014, https://doi.org/10.1088/1361-6560/aae451