Progress in Medical Physics (한국의학물리학회지:의학물리)

Korean Society of Medical Physics (한국의학물리학회)
권호 표지
DOI QR코드

DOI QR Code

Evaluation of Dose Distributions Recalculated with Per-field Measurement Data under the Condition of Respiratory Motion during IMRT for Liver Cancer

간암 환자의 세기조절방사선치료 시 호흡에 의한 움직임 조건에서 측정된 조사면 별 선량결과를 기반으로 재계산한 체내 선량분포 평가

  • Song, Ju-Young (Department of Radiation Oncology, Chonnam National University Medical School) ;
  • Kim, Yong-Hyeob (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
  • Jeong, Jae-Uk (Department of Radiation Oncology, Chonnam National University Hwasun Hospital) ;
  • Yoon, Mee Sun (Department of Radiation Oncology, Chonnam National University Medical School) ;
  • Ahn, Sung-Ja (Department of Radiation Oncology, Chonnam National University Medical School) ;
  • Chung, Woong-Ki (Department of Radiation Oncology, Chonnam National University Medical School) ;
  • Nam, Taek-Keun (Department of Radiation Oncology, Chonnam National University Medical School)
  • 송주영 (전남대학교 의과대학 방사선종양학교실) ;
  • 김용협 (화순전남대학교병원 방사선종양학과) ;
  • 정재욱 (화순전남대학교병원 방사선종양학과) ;
  • 윤미선 (전남대학교 의과대학 방사선종양학교실) ;
  • 안성자 (전남대학교 의과대학 방사선종양학교실) ;
  • 정웅기 (전남대학교 의과대학 방사선종양학교실) ;
  • 남택근 (전남대학교 의과대학 방사선종양학교실)
  • Received : 2014.05.08
  • Accepted : 2014.06.09
  • Published : 2014.06.30
Download PDF
⟨ Previous Next ⟩

Abstract

The dose distributions within the real volumes of tumor targets and critical organs during internal target volume-based intensity-modulated radiation therapy (ITV-IMRT) for liver cancer were recalculated by applying the effects of actual respiratory organ motion, and the dosimetric features were analyzed through comparison with gating IMRT (Gate-IMRT) plan results. The ITV was created using MIM software, and a moving phantom was used to simulate respiratory motion. The doses were recalculated with a 3 dose-volume histogram (3DVH) program based on the per-field data measured with a MapCHECK2 2-dimensional diode detector array. Although a sufficient prescription dose covered the PTV during ITV-IMRT delivery, the dose homogeneity in the PTV was inferior to that with the Gate-IMRT plan. We confirmed that there were higher doses to the organs-at-risk (OARs) with ITV-IMRT, as expected when using an enlarged field, but the increased dose to the spinal cord was not significant and the increased doses to the liver and kidney could be considered as minor when the reinforced constraints were applied during IMRT plan optimization. Because the Gate-IMRT method also has disadvantages such as unsuspected dosimetric variations when applying the gating system and an increased treatment time, it is better to perform a prior analysis of the patient's respiratory condition and the importance and fulfillment of the IMRT plan dose constraints in order to select an optimal IMRT method with which to correct the respiratory organ motional effect.

내부표적체적을 기반으로 계획된 간암 환자의 세기조절방사선치료에서 호흡에 의한 장기의 움직임 영향을 적용하여 체내 실제 종양 부피와 중요 장기 부피에서의 선량분포를 재계산하고, 호흡동조 방식의 세기조절방사선치료 계획 결과와 비교를 통한 선량적 특성을 분석하였다. 내부표적체적은 MIM 프로그램을 사용하여 형성하였고, 호흡에 의한 장기 움직임을 모사할 수 있는 구동 팬텀을 사용하였다. 체내 선량분포는 세기조절방사선치료의 품질보증 과정에서 2차원 다이오드 검출기 배열 장치인 MapCHECK2로 측정한 조사면 별 측정 결과를 기반으로 3DVH 프로그램으로 재계산 하였다. 내부표적체적 기반의 세기조절방사선치료 수행 시 계획표적체적에 충분히 처방선량이 조사되었지만, 선량의 균일도는 호흡동조 방식의 세기조절방사선치료와 비교 시 열등한 결과를 보였다. 상대적으로 더 큰 조사면을 사용하는 내부표적체적 기반의 세기조절방사선치료에서 손상위험장기체적에 더 높은 선량이 조사됨을 확인할 수 있었지만, 척수에 증가된 선량은 부작용 발생확률에 큰 영향을 주지 않는 적은 양이었고, 정상 간이나 신장 부위의 증가된 선량도 최적화 과정에서 좀 더 선량감소 조건을 강화한다면 큰 영향이 없을 것으로 평가되었다. 호흡동조 방식의 세기조절방사선치료가 치료계획에서는 더 좋은 선량분포를 보이고 있으나, 실제 구현 과정에서 다엽콜리메이터의 움직임 오류로 인한 선량의 오차와 치료시간의 증가 측면의 단점이 있으므로, 환자 호흡 상태 및 손상위험장기의 선량제한 값에 대한 사전 분석을 통해 환자 별 최적의 세기조절방사선치료 기법을 선정하여 적용하는 것이 타당하다고 생각된다.

Keywords

References

  1. Duan J, Shen S, Fiveash JB, et al: Dosimetric effect of respiration-gated beam on IMRT delivery. Med Phys 30(8):2241-2252 (2003) https://doi.org/10.1118/1.1592017
  2. Ahmed RS, Shen S, Ove R, et al: Intensity modulated with respiratory gating for radiotherapy of the pleural space. Med Dosim 32(1):16-22 (2007) https://doi.org/10.1016/j.meddos.2006.10.002
  3. van der Geld YG, van Triest B, Verbakel WF, et al: Evaluation of four-dimensional computed tomography-based intensity-modulated and respiratory-gated radiotherapy techniques for pancreatic carcinoma. Int J Radiat Oncol Biol Phys 72(4):1215-1220 (2008) https://doi.org/10.1016/j.ijrobp.2008.07.010
  4. Seco J, Sharp GC, Wu Z, et al: Dosimetric impact of motion in free-breathing and gated lung radiotherapy: a 4D Monte Carlo study of intrafraction and interfraction effects. Med Phys 35(1):356-366 (2008) https://doi.org/10.1118/1.2821704
  5. Chen H, Wu A, Brandner ED, et al: Dosimetric evaluations of the interplay effect in respiratory-gated intensity-modulated radiation therapy. Med Phys 36(3):893-903 (2009) https://doi.org/10.1118/1.3070542
  6. Kang H, Yorke ED, Yang J, et al: Evaluation of tumor motion effects on dose distribution for hypofractionated intensitymodulated radiotherapy of non-small-cell lung cancer. J Appl Clin Med Phys 11(3):78-89 (2010) https://doi.org/10.1120/jacmp.v11i3.3182
  7. Cheong KH, Kang SK, Lee M, et al: Evaluation of delivered monitor unit accuracy of gated step-and-shoot IMRT using a two-dimensional detector array. Med Phys 37(3):1146-1151 (2010) https://doi.org/10.1118/1.3310806
  8. Yoganathan SA, Maria Das KJ, Agarwal A, et al: Performance evaluation of respiratory motion-synchronized dynamic IMRT delivery. J Appl Clin Med Phys 14(3):39-51 (2013) https://doi.org/10.1120/jacmp.v14i3.4103
  9. Hugo GD, Agazaryan N, Solberg TD: An evaluation of gating window size, delivery method, and composite field dosimetry of respiratory-gated IMRT. Med Phys 29(11):2517-2525 (2002) https://doi.org/10.1118/1.1514578
  10. Xi M, Liu MZ, Deng XW, et al: Defining internal target volume (ITV) for hepatocellular carcinoma using four-dimensional CT. Radiother Oncol 84(3):272-278 (2007) https://doi.org/10.1016/j.radonc.2007.07.021
  11. Xi M, Liu MZ, Zhang L, et al: How many sets of 4DCT images are sufficient to determine internal target volume for liver radiotherapy? Radiother Oncol 92(2):255-259 (2009) https://doi.org/10.1016/j.radonc.2009.05.007
  12. Reitz B, Parda DS, Colonias A, et al: Investigation of simple IMRT delivery techniques for non-small cell lung cancer patients with respiratory motion using 4DCT. Med Dosim 34(2): 158-169 (2009) https://doi.org/10.1016/j.meddos.2008.07.001
  13. Speight R, Sykes J, Lindsay R, et al: The evaluation of a deformable image registration segmentation technique for semi-automating internal target volume (ITV) production from 4DCT images of lung stereotactic body radiotherapy (SBRT) patients. Radiother Oncol 98(2):277-283 (2011) https://doi.org/10.1016/j.radonc.2010.12.007
  14. Wu Q, Mohan R, Morris M, et al: Simultaneous integrated boost intensity modulated radiotherapy for locally advanced head-and-neck squamous cell carcinomas. I: dosimetric results. Int J Radiat Oncol Biol Phys 56(2):573-585 (2003) https://doi.org/10.1016/S0360-3016(02)04617-5
  15. Olch AJ: Evaluation of the accuracy of 3DVH software estimates of dose to virtual ion chamber and film in composite IMRT QA. Med Phys 39(1):81-86 (2012) https://doi.org/10.1118/1.3666771
  16. Carrasco P, Jornet N, Latorre A, et al: 3D DVH-based metric analysis versus per-beam planar analysis in IMRT pretreatment verification. Med Phys 39(8):5040-5049 (2012) https://doi.org/10.1118/1.4736949

Cited by

  1. A simple DVH generation technique for various radiotherapy treatment planning systems for an independent information system vol.67, pp.1, 2014, https://doi.org/10.3938/jkps.67.254
  2. Dosimetric analysis on the effect of tumor motion in IMRT for liver cancer: comparison of TomoTherapy and VMAT using the Delta4 Hexa-Motion system vol.79, pp.5, 2014, https://doi.org/10.1007/s40042-021-00150-x