Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
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Effects of Arc Number or Rotation Range upon Dose Distribution at RapidArc Planning for Liver Cancer

간암환자를 대상으로 한 래피드아크 치료계획에서 아크수 및 회전범위가 선량분포에 미치는 영향

  • Park, Hae-Jin (Department of Radiation Oncology, Ajou University Hospital) ;
  • Kim, Mi-Hwa (Department of Radiation Oncology, Ajou University Hospital) ;
  • Chun, Mi-Son (Department of Radiation Oncology, Ajou University Hospital) ;
  • Oh, Yeong-Teak (Department of Radiation Oncology, Ajou University Hospital) ;
  • Suh, Tae-Suk (Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea)
  • 박혜진 (아주대학교병원 방사선종양학과) ;
  • 김미화 (아주대학교병원 방사선종양학과) ;
  • 전미선 (아주대학교병원 방사선종양학과) ;
  • 오영택 (아주대학교병원 방사선종양학과) ;
  • 서태석 (가톨릭대학교 의과대학 의공학교실)
  • Received : 2010.03.11
  • Accepted : 2010.04.22
  • Published : 2010.06.30
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Abstract

In this paper, we evaluated the performance of 3D CRT, IMRT and three kind of RA plannings to investigate the clinical effect of RA with liver cancer case. The patient undergoing liver cancer of small volume and somewhat constant motion were selected. We performed 3D CRT, IMRT and RA plannings such as 2RA, limited triple arcs (3RA) and 3MRA with Eclipse version 8.6.15. The same dose volume objectives were defined for only CTV, PTV and body except heart, liver and partial body in IMRT and RA plannings. The steepness of dose gradient around tumor was determined by the Normal Tissue Objective function with the same parameters in place of respective definitions of dose volume objectives for the normal organs. The approach between the defined dose constraints and the practical DVH of CTV, PTV and Body was the best in 3MRA and the worst in IMRT. The DVHs were almost the same among RAs. Plans were evaluated using Conformity Index (CI), Homogeneity Index (HI) and Quality of coverage (QoC) by RTOG after prescription with dose level surrounding 98% of PTV in the respective plans. As a result, 3MRA planning showed the better favorable indices than that of the others and achieved the lowest MUs. In this study, RA planning is a technique that is possible to obtain the faster and better dose distribution than 3D CRT or IMRT techniques. Our result suggest that 3MRA planning is able to reduce the MUs further, keeping a similar or better targer dose homogeneity, conformity and sparing normal tissue than 2RA or 3RA.

본 논문에서는 간암 환자를 대상으로 3차원입체조형치료와 세기조절방사선치료와 3종류의 래피드아크 치료를 위한 치료계획을 수행하여 각각의 선량분포와 선량 체적 히스토그램(Dose Volume Histogram, DVH)의 특성을 비교, 평가하고 이를 통해 래피드아크 치료 환자에 대한 적절한 갠트리 회전수의 범위를 제시하고자 하였다. 치료계획은 작은 종양의 용적을 가지며 내부 장기 및 종양의 움직임이 비교적 작은 간암환자를 대상으로 3차원입체조형치료와 세기조절방사선치료와 더블아크(double arcs)와 제한적인 트리플아크(limited triple arcs)와 멀티플아크(multiple arcs)치료에 대해 Eclipse 8.6 버전에서 시행하였다. 또한 치료계획 시 임상표적용적(Clinical Target Volume, CTV)과 치료표적용적(Planning Target Volume, PTV)에 동일한 최적화 조건을 적용하였고, 각각의 정상조직에는 개별적인 선량 제한치 적용대신 종양 주변 정상조직에서의 선량 감소율을 일괄적으로 적용하였다. 임상표적용적과 치료표적용적의 전체 몸에 적용한 치료계획 선량 제한치에 대한 실제 계산결과의 만족도는 래피드아크가 세기조절방사선치료보다 높았으며 래피드아크에서 더블아크와 제한적인 트리플아크와 멀티플아크는 만족도가 거의 동일하였다. 또한 각 치료계획에서 치료표적용적에 계획한 선량 제한치에 따라 SALT group이 제안한 Conformity Index (CI)가 0.98인 선량 분포범위에 처방선량을 결정하였다. 이때 RTOG에서 제안한 CI, Homogeneity Index (HI), Quality of Coverage (QOC)와 Lomax and Scheib에서 제안한 Healthy tissue conformity index (HTCI) 등을 평가하였다. 항목별로 차이는 있지만 총체적인 평가 결과는 멀티플아크가 전체적으로 좋았으며 모니터 단위 값의 비교에서도 멀티플아크가 가장 작았다. 본 연구를 통하여 래피드아크 치료는 기존에 시행하고 있는 3차원입체조형치료 또는 세기조절방사선치료 기법보다 더욱 최적의 선량 분포를 구현한다는 것을 알 수 있었다. 또한 래피드아크 치료계획에서 멀티플아크 치료계획은 더블 또는 제한된 트리플아크 치료계획보다 모니터 단위 값이 작고, 선량의 균질성 및 종양내의 최소선량은 비슷하거나 좋아지는 동시에 주변 정상조직에는 선량이 감소되는 것을 알 수 있었다.

Keywords

References

  1. Muren LP, Wasbo E, Helle SI, et al: Intensity-modulatedradiotherapy of pelvic lymph nodes in locally advanced prostatecancer: Planning procedures and early experiences. Int JRadiation Oncology Biol Phys 71:1034-1041 (2009)
  2. Liu YM, Shiau CY, Lee ML, et al: The role and strategyof IMRT in radiotherapy of pelvis tumors: Dose escalation andcritical organ sparing in prostate cancer. Int J Radiation Oncology Biol Phys 67:1113-1123 (2007) https://doi.org/10.1016/j.ijrobp.2006.10.009
  3. Iori M, Cattaneo GM, Cagni E, et al: Dose-volume and biological-model based comparision between helical tomotherapyand (inverse-planned) IMAT for prostate tumours. Radiother Oncol 88:34-45 (2008) https://doi.org/10.1016/j.radonc.2008.03.003
  4. Otto K: Volumetric modulated arc therapy: IMRT in a singlegantry arc. Med Phys 35:310-317 (2007) https://doi.org/10.1118/1.2818738
  5. Korreman S, Medin J, Kjar-Kristoffersen F: Dosimetricverificatio of RapidArc treatment delivery. Acta Oncol 48:185-191(2009) https://doi.org/10.1080/02841860802287116
  6. Otto K: Patient-specific quality assurance method for VAMTtreatment delivery. Med Phys 36:4530-4535 (2009) https://doi.org/10.1118/1.3213085
  7. Popescu CC, Olivotto IA, Beckham WA, et al: Volumetricmodulated arc therapy improves dosimetry and reduces treatmenttime compared to conventional intensity-modulated radiotherapyfor locoregional radiotherapy of left-sided breast cancerand internal mammary nodes. Int J Radiation Oncology Biol Phys 76:287-295 (2009)
  8. Palma D, Vollans EPJ, James K, et al: Volumetric modulatedarc therapy for delivery of prostate radiotherapy: Comparisionwith intensity-modulated radiotherapy and three-dimensionalconformal radiotherapy. Int J Radiation Oncology Biol Phys 72:996-1001 (2008) https://doi.org/10.1016/j.ijrobp.2008.02.047
  9. Verbakel WFAR, Cuijpers JP, Hoffmans D, et al: Volumetricintensity-modulated arc therapy VS. conventional IMRTin Head-and-Neck cancer: A comparision planning and dosimetricstudy. Int J Radiation Oncology Biol Phys 74:252-259(2009) https://doi.org/10.1016/j.ijrobp.2008.12.033
  10. Zhang P, Happersett L, Hunt M, et al: Volumetric modulatedarc therapy: Planning and evaluation for prostate cancercases. Int J Radiation Oncology Biol Phys 76:1456-1462 (2009)
  11. Lagerwaard FJ, Meijer OWM, Hoorn EAP, et al: Volumetricmodulated arc radiotherapy for vestibular schwannomas. Int J Radiation Oncology Biol Phys 74:610-615 (2009) https://doi.org/10.1016/j.ijrobp.2008.12.076
  12. Kjar-Kristoffersen F, Ohlhues L, Medin J, et al: Rapid-Arc volumetric modulated therapy planning for prostate cancerpatients. Acta Oncol 48:227-232 (2009) https://doi.org/10.1080/02841860802266748
  13. Vanetti E, Clivio A, Nicolini G, et al: Volumetric-modulatedarc radiotherapy for carcinomas of the oro-pharynx: atreatment planning comparison with fixed field IMRT. Radiother Oncol 92:111-117 (2009) https://doi.org/10.1016/j.radonc.2008.12.008
  14. Clivio A, Fogliata A, Franzetti-Pellanda A, et al:Volumetric-modulated arc radiotherapy for carcinomas of theanal canal: A treatment planning comparison with fixed fieldIMRT. Radiother Oncol 92:118-124 (2009) https://doi.org/10.1016/j.radonc.2008.12.020
  15. Vanetti E, Clivio A, Nicolini G, et al: A treatment planningstudy comparing volumetric ar modulatio with RapidArc and fixedfield IMRT for cervix uteri radiotherapy. Radiother Oncol 89:180-191 (2009)
  16. Feuvret L, Noel G, Mazeron JJ, et al: Conformity index:A review. Int J Radiation Oncology Biol Phys 64:333-342 (2006) https://doi.org/10.1016/j.ijrobp.2005.09.028
  17. Benford JL, Hansen VN, Mcnair HA, et al: Treatment oflung cancer using volumetric modulated arc therapy and imageauidance: A case study. Acta Oncol 47:1438-1443 (2008) https://doi.org/10.1080/02841860802282778
  18. Verbakel WFAR, Cuijpers SSJP, Slotman BJ, et al:Rapid delivery of sterotactic radiotherapy for peripheral lung tumorsusing volumetric intensity-modulated arcs. Radiother Oncol 93:122-124 (2009) https://doi.org/10.1016/j.radonc.2009.05.020
  19. Bignardi M, Cozzi L, Fogliata A, et al: Critical appraisalof volumetric modulatd arc therapy in sterotactic body radiationtherapy for metastases to abdominal lymph nodes. Int J Radiation Oncology Biol Phys 75:1570-1577 (2009) https://doi.org/10.1016/j.ijrobp.2009.05.035