A Study to Evaluate the Efficacy of CBCT and EXACTRAC on Spine Stereotactic Body Radiation Therapy

CBCT와 EXACTRAC을 이용한 Spine SBRT의 유용성 평가

  • Choi, Woo Keun (Department of Radiation Oncology, Samsung Medical Center) ;
  • Park, Su Yeon (Department of Radiation Oncology, Samsung Medical Center) ;
  • Park, Do Keun (Department of Radiation Oncology, Samsung Medical Center) ;
  • Song, Ki Won (Department of Radiation Oncology, Samsung Medical Center)
  • 최우근 (삼성서울병원 방사선종양학과) ;
  • 박수연 (삼성서울병원 방사선종양학과) ;
  • 박도근 (삼성서울병원 방사선종양학과) ;
  • 송기원 (삼성서울병원 방사선종양학과)
  • Received : 2013.05.24
  • Accepted : 2013.09.03
  • Published : 2013.09.30

Abstract

Purpose: This study is to evaluate the efficacy of the CBCT and EXACTRAC the image on the spine stereotactic body radiation treatment. Materials and Methods: The study compared the accuracy of the dose distribution for changes in the real QA phantom for The shape of the body of the phantom was performed. Novalis treatment artificially set up at the center and to the right, on the Plan 1 mm, 2 mm, 3 mm in front 1 mm, 2 mm, 3 mm and upwards 1 mm, 2 mm, 3 mm and $0.5^{\circ}$ by moving side to side Exactrac error correction and error values of CBCT and plan changes on the dose distribution were recorded and analyzed. Results: Cubic Phantom of the experimental error, the error correction Exactrac X-ray 6D Translation in the direction of the 0.18 mm, Rotation direction was $0.07^{\circ}$. Translation in the direction of the 3D CBCT 0.15 mm Rotation direction was $0.04^{\circ}$. DVH dose distribution using the results of the AP evaluate the change in the direction of change was greatest when moving. Conclusion: ExacTrac image-guided radiation therapy with a common easy and fast to get pictures from all angles, from the advantage of CBCT showed a potential alternative. But every accurate information compared with CT treatment planning and treatment of patients with more accurate than the CBCT ExacTrac the location provided. Changes in the dose distribution in the experiment results show that the treatment of spinal SBRT set up some image correction due to errors at the target and enter the spinal cord dose showed that significant differences appear.

목 적: CBCT와 EXACTRAC을 이용한 Spine 체부정위적방사선 치료 Set up 시 이미지 보정 값과 실제 오차의 차이를 측정하고, 이 오차 값이 미치는 선량분포를 계산하여 CBCT와 EXACTRAC의 유용성을 평가하고자 한다. 대상 및 방법: Set up 오차 보정 값과 실제 오차 비교 실험을 위해서 QA용 Cubic phantom (The EASY CUBEr, Euromechanics, Schwarzenbruck, Germany)을 이용하였고, phantom의 중심축을 인위적으로 LR 방향으로 -1 mm, -2 mm, -3 mm SI 방향으로 1 mm, 2 mm, 3 mm 그리고 AP방향으로 1 mm, 2 mm, 3 mm 이동시켰으며, 중심축을 $0.5^{\circ}$씩 좌우로 회전시켜 CBCT와 EXACTRAC의 Auto matching 보정 값과 비교 측정하였으며, 이동된 오차 값을 가정하여 Rando Phantom을 이용한 Spine SBRT 플랜에 적용하여 재계산을 시행하였다. 결 과: Set up 보정 값과 실제 오차 비교실험에서 3D CBCT의 평균값은 LR, SI, AP 방향으로 0.15 mm 회전방향으로 $0.04^{\circ}$였고 EXACTRAC의 평균값은 LR, SI, AP 방향으로 0.18 mm 회전방향으로 $0.07^{\circ}$였다. 이동 값 오차를 가정한 선량 재계산 결과, SI방향 2, 3 mm 이동 시 $V_{10}$ (종양의 용적에 10 Gy가 들어가는 선량) Volume이 각각 10.574%, 10.712%가 나타났고 LR방향 -3 mm 이동 시 12.076%로 가장 높게 나타났다. 결 론: CBCT와 EXACTRAC의 Set up 보정 값과 실제 오차는 1 mm, $0.1^{\circ}$ 미만으로 두 시스템 모두 매우 정밀한 set up 오차보정을 보였다. 그러나 선량 재계산 시 3 mm 이상의 오차가 발생한 경우, Spine SBRT 치료 시 Spinal cord에 들어가는 선량이 $V_{10}$에서 3% 이상 최대선량 13 Gy 이상 증가함으로서 치명적인 흡수선량 오류가 발생할 수 있음을 확인하였다. 따라서 본 저자는 1회에 한한 Spine SBRT 치료 시 정확도 측면에서 종양의 단면 정보를 위치적으로 제공하는 CBCT가 더 유용할 것으로 사료된다.

Keywords

References

  1. Thomas SR, Rajeev B, Sanjay, et al.: A comparative study to evaluate the efficacy of on board imaging with cone beam CT using target registration in patients with lung tumors undergoing stereotactic body radiation therapy and comparison with Exactrac using skeletal registration on Novalis Tx. Journal of Cancer Research and Therapeutics 2011;7:304-307 https://doi.org/10.4103/0973-1482.87029
  2. Jinkoo K, Jian YJ, Nicole W, et al.: Image-guided localization accuracy of stereoscopic planar and volumetric imaging method for stereotactic radiation surgery and stereotactic body radiation therapy: a phantom study. Int J Radiat Oncol Biol Phys 2011;79:1588-1596 https://doi.org/10.1016/j.ijrobp.2010.05.052
  3. Zheng C, Zhiheng W, Jennifer C, et al.: 6D image guidance for spinal non-invasive stereotactic body radiation therapy: Comparison between ExacTrac X-ray 6D with kilo-voltage cone-beam CT. Radiotherapy and Oncology 2010;95:116-121 https://doi.org/10.1016/j.radonc.2009.12.036
  4. Derek H, Fiona L, Renee K, et al.: Spine stereotactic body radiotherapy utilizing cone-beam CT image-guidance with a robotic couch: intrafraction motion analysis accounting for all six degrees of freedom. Int J Radiat Oncol Biol Phys 2012; 82:e555-562 https://doi.org/10.1016/j.ijrobp.2011.06.1980
  5. Jinli M, Zheng C, Zhiheng W, et al.: ExacTrac X-ray 6 degree- of-freedom image-guidance for intracranial non-invasive stereotactic radiotherapy: comparison with kilo-voltage conebeam CT. Radiother Oncol 2009;93:602-608 https://doi.org/10.1016/j.radonc.2009.09.009
  6. Orit G, Annette E, Rojano K, et al.: Influence of rotations on dose distributions in spinal stereotactic body radiotherapy (SBRT). Int J Radiat Oncol Biol Phys 2009;73:1596-1601 https://doi.org/10.1016/j.ijrobp.2008.12.025