Analysis of the cause of dose delivery errors due to changes in abdominal gas volume during MRgART pancreatic cancer

췌장암 MRgART시 복부가스용적 변화에 의한 선량전달오류 원인 분석

  • Ha, Min Yong (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Son, Sang Jun (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Kim, Chan Yong (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Lee, Je Hee (Department of Radiation Oncology, Seoul National University Hospital)
  • 하민용 (서울대학교병원 방사선종양학과) ;
  • 손상준 (서울대학교병원 방사선종양학과) ;
  • 김찬용 (서울대학교병원 방사선종양학과) ;
  • 이제희 (서울대학교병원 방사선종양학과)
  • Published : 2020.12.27

Abstract

Purpose: The purpose of this study is to confirm the matching of the electron density between tissue and gas due to variation of abdominal gas volume in MRgART (Magnetic Resonance-guided Adaptive Radiation Therapy) for pancreatic cancer patients, and to confirm the effect on the dose change and treatment time. Materials and Methods: We compared the PTV and OAR doses of the initial plan and the AGC(Abdominal gas correction) plans to one pancreatic cancer patient who treated with MRgART using the ViewRay MRIdian System (Viewray, USA) at this clinic. In the 4fx AGC plans, Beam ON(%) according to the patient's motion error was checked to confirm the effect of abdominal gas volume on treatment time. Results: Comparing the Initial plan with the average value of AGC plan, the dose difference was -7 to 0.1% in OAR and decreased by 0.16% on average, and in PTV, the dose decreased by 4.5% to 5.5% and decreased by 5.1% on average. In Adaptive treatment, as the abdominal gas volume increased, the Beam ON(%) decreased. Conclusion: Abdominal gas volume variation causes dose change due to inaccurate electron density matching between tissue and gas. In addition, if the abdominal gas volume increases, the Beam ON(%) decreases, and the treatment time may increase due to the motion error of the patient. Therefore, in MRgART, it is necessary to check the electron density matching and minimize the variability of the abdominal gas.

목 적: 본 연구에서는 췌장암 환자 MRgART(Magnetic Resonance-guided Adaptive Radiation Therapy)시 복부가스용적변화로 인하여 Image fusion 과정에서 생길 수 있는 조직과 가스의 전자밀도 매칭오류를 확인하고 그에 따른 선량 변화와 치료시간에 미치는 영향을 확인해 보고자 한다. 대상 및 방법: 본원에서 ViewRay MRIdian System (Viewray, USA)를 이용하여 MRgART를 시행한 췌장암 환자 중 최초 simulation시와 비교하여 복부가스용적감소가 발생한 환자를 대상으로 Initial plan과 복부가스 전자밀도를 수정한 AGC(Abdominal gas correction) plan의 PTV와 OAR선량을 비교하였고, 총4회 Adaptive 치료에서 환자의 Beam ON(%)을 확인하여 복부가스용적이 치료시간에 미치는 영향을 확인해 보았다. 결 과: Initial plan에서의 Mean, Minimum, Maximum 선량과 AGC plan의 Mean, Minimum, Maximum 선량평균값을 비교하였을 시 OAR에서는 -7~0.1%의 선량차이를 보였으며 평균 0.16% 감소하였고, PTV에서는 4.5~5.5%의 선량이 감소하였으며 평균 5.1%의 선량이 감소하였다. Adaptive치료 시 복부가스용적이 증가할수록 Beam ON(%)이 감소하였다. 결 론: Initial plan과 Adaptive plan간 복부가스용적 변화는 Adaptive plan시 전자밀도매칭 오류로 이어질 수 있으며 이는 PTV와 주변OAR의 선량분포를 변화시키므로 Adaptive plan시 영상 fusion 과정에서 가스용적을 보정한 정확한 전자밀도매칭은 필수적인 요소이다. 또한 복부가스용적이 커질수록 Beam ON(%)이 감소하여 환자의 Motion error로 인한 치료시간이 증가될 수 있다. 따라서 MRgART시에는 전자밀도매칭을 확인하고 복부가스의 가변성을 최소화 하여야 한다.

Keywords

References

  1. Hidalgo M. Pancreatic cancer. N Engl J Med 2010;362:1605-1617. https://doi.org/10.1056/NEJMra0901557
  2. Herman JM, Wild AT, Wang H, Tran PT, Chang KJ, Taylor GE, et al. Randomized phase III multi-institutional study of TNFerade biologic with fluorouracil and radiotherapy for locally advanced pancreatic cancer: final results. J Clin Oncol Off J Am Soc Clin Oncol. 2013;31:886-94. https://doi.org/10.1200/JCO.2012.44.7516
  3. NCCN Clinical practice guidelines in oncology V.1.2008:pancreatic adenocarcinoma.
  4. Chang DT, Schellenberg D, Shen J, et al. Stereotactic radiotherapy for unresectable adenocarcinoma of the pancreas. Cancer. 2009; 115(3): 665-672. https://doi.org/10.1002/cncr.24059
  5. Koong AC, Le QT, Ho A, et al. Phase I study of stereotactic radiosurgery in patients with locally advanced pancreatic cancer. Int J Radiat Oncol Biol Phys. 2004; 58(4): 1017-1021. https://doi.org/10.1016/j.ijrobp.2003.11.004
  6. Noel CE, Parikh PJ, Spencer CR, et al. Comparison of onboard low-field magnetic resonance imaging versus onboard computed tomography for anatomy visualization in radiotherapy. Acta Oncol. 2015; 54(9): 1474-1482. https://doi.org/10.3109/0284186X.2015.1062541
  7. Liu F, Erickson BA, Peng C, Li XA. Characterization and management of interfractional anatomic changes for pancreatic cancer radiotherapy. Int J Radiat Oncol Biol Phys. 2012; 83(3): e423-e429. https://doi.org/10.1016/j.ijrobp.2011.12.073
  8. Rudra S, Jiang N, Rosenberg SA, Olsen JR, Roach MC, and Wan L, et al. Using adaptive magnetic resonance image-guided radiation therapy for treatment of inoperable pancreatic cancer. Cancer Med 2019;8:2123-2132. https://doi.org/10.1002/cam4.2100
  9. Henke L, Kashani R, Yang D, et al. Simulated online adaptive magnetic resonance-guided stereotactic body radiation therapy for the treatment of oligometastatic disease of the abdomen and central thorax: characterization of potential advantages. Int J Radiat Oncol Biol Phys. 2016; 96(5): 1078-1086. https://doi.org/10.1016/j.ijrobp.2016.08.036
  10. Henke L, Kashani R, Robinson C, et al. Phase I trial of stereotactic MR-guided online adaptive radiation therapy (SMART) for the treatment of oligometastatic or unresectable primary malignancies of the abdomen. Radiother Oncol. 2018; 126(3): 519-526. https://doi.org/10.1016/j.radonc.2017.11.032
  11. Hunt A, Hansen VN, Oelfke U, Nill S, and Hafeez S. Adaptive radiotherapy enabled by MRI guidance. Clin Oncol (R Coll Radiol) 2018;30:711-719. https://doi.org/10.1016/j.clon.2018.08.001
  12. Onal C, Guler OC, and Dolek Y. The impact of air pockets around the vaginal cylinder on vaginal vault brachytherapy. Br J Radiol 2015;88 20140694. https://doi.org/10.1259/bjr.20140694
  13. Berger T, Petersen JBB, Lindegaard JC, Fokdal LU, and Tanderup K. Impact of bowel gas and body outline variations on total accumulated dose with intensity-modulated proton therapy in locally advanced cervical cancer patients. Acta Oncol 2017;56:1472-1478. https://doi.org/10.1080/0284186X.2017.1376753
  14. Estabrook NC, Corn JB, Ewingmm, Cardenes HR, and Das IJ. Dosimetric impact of gastrointestinal air column in radiation treatment of pancreatic cancer. Br J Radiol 2018;91 20170512.
  15. Pathmanathan, Angela U. van As, Nicholas J. Kerkmeijer, Linda G.W. Magnetic Resonance ImagingGuided Adaptive Radiation Therapy: A "Game Changer" for Prostate Treatment? Int J Radiation Oncol Biol Phys, Vol. 100, No. 2, pp. 361e373, 20180360-3016
  16. Eui Kyu Chie. Radiation Therapy in Pancreatic Cancer Korean J Gastroenterol 2008;51:101-110
  17. Botman R. Tetar S.U. Palacios M.A. Slotman B.J. Lagerwaard F.J. Bruynzeel A.M.E. The clinical introduction of MR-guided radiation therapy from a RTT perspective. Clin Transl Radiat Oncol. 2019; 18: 140-145 https://doi.org/10.1016/j.ctro.2019.04.019
  18. Bohoudi O, Bruynzeel AME, Senan S, Cuijpers JP, Slotman BJ, and Lagerwaard FJ, et al. Fast and robust online adaptive planning in stereotactic MR-guided adaptive radiation therapy (SMART) for pancreatic cancer. Radiother Oncol 2017;125:439-444. https://doi.org/10.1016/j.radonc.2017.07.028
  19. Spieler B, Patel NV, Breto AL, Ford J, Stoyanova R, and Zavala-Romero O, et al. Automatic segmentation of abdominal anatomy by artificial intelligence (AI) in adaptive radiotherapy of pancreatic cancer. Int J Radiat Oncol Biol Phys 2019;105:E130-E131.
  20. Men K, Zhang T, Chen X, Chen B, Tang Y, and Wang S, et al. Fully automatic and robust segmentation of the clinical target volume for radiotherapy of breast cancer using big data and deep learning. Phys Med 2018;50:13-19. https://doi.org/10.1016/j.ejmp.2018.05.006