DOI QR코드

DOI QR Code

Assessment of Dose Distributions According to Low Magnetic Field Effect for Prostate SABR

  • Son, Jaeman (Department of Radiation Oncology, Seoul National University Hospital) ;
  • An, Hyun Joon (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Choi, Chang Heon (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Chie, Eui Kyu (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Kim, Jin Ho (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Park, Jong Min (Department of Radiation Oncology, Seoul National University Hospital) ;
  • Kim, Jung-in (Department of Radiation Oncology, Seoul National University Hospital)
  • Received : 2018.12.06
  • Accepted : 2018.12.26
  • Published : 2019.03.31

Abstract

Background: Stereotactic ablative radiotherapy (SABR) plans in prostate cancer are compared and analyzed to investigate the low magnetic effect (0.35 T) on the dose distribution, with various dosimetric parameters according to low magnetic field. Materials and Methods: Twenty patients who received a 36.25 Gy in five fractions using the MR-IGRT system (ViewRay) were studied. For planning target volume (PTV), the point mean dose ($D_{mean}$), maximum dose ($D_{max}$), minimum dose ($D_{min}$) and volumes receiving 100% ($V_{100%}$), 95% ($V_{95%}$), and 90% ($V_{90%}$) of the total dose. For organs-at-risk (OARs), the differences compared using $D_{max}$, $V_{50%}$, $V_{80%}$, $V_{90%}$, and $V_{100%}$ of the rectum; $D_{max}$, $V_{50%}$, $V_{30Gy}$, $V_{100%}$ of the bladder; and $V_{30Gy}$ of both left and right femoral heads. For both the outer and inner shells near the skin, $D_{mean}$, $D_{min}$, and $D_{max}$ were compared. Results and Discussion: In PTV analysis, the maximum difference in volumes ($V_{100%}$, $V_{95%}$, and $V_{90%}$) according to low magnetic field was $0.54{\pm}0.63%$ in $V_{100%}$. For OAR, there was no significant difference of dose distribution on account of the low magnetic field. In results of the shells, although there were no noticeable differences in dose distribution, the average difference of dose distribution for the outer shell was $1.28{\pm}1.08Gy$ for $D_{max}$. Conclusion: In the PTV and OARs for prostate cancer, there are no statistically-significant differences between the plan calculated with and without a magnetic field. However, we confirm that the dose distribution significantly increases near the body shell when a magnetic field is applied.

Acknowledgement

Supported by : National Research Foundation of Korea (NRF)

References

  1. Jemal A, Bray F, Center MM, Ferlay J, Ward E, Forman D. Global cancer statistics. CA. Cancer. J. Clin. 2011;61(2):69-90. https://doi.org/10.3322/caac.20107
  2. Loblaw A, et al. Prostate stereotactic ablative body radiotherapy using a standard linear accelerator: toxicity, biochemical, and pathological outcomes. Radiother. Oncol. 2013;107(2):153-158. https://doi.org/10.1016/j.radonc.2013.03.022
  3. Sahgal A, et al. The Canadian Association of Radiation Oncology scope of practice guidelines for lung, liver and spine stereotactic body radiotherapy. Clin. Oncol. 2012;24(9):629-639. https://doi.org/10.1016/j.clon.2012.04.006
  4. Ritter M. Rationale, conduct, and outcome using hypofractionated radiotherapy in prostate cancer. Semin. Radiat. Oncol. 2008;18(4):249-256. https://doi.org/10.1016/j.semradonc.2008.04.007
  5. Brenner DJ, Hall EJ. Hypofractionation in prostate cancer radiotherapy. Transl. Cancer. Res. 2018;7(6):S632-S639. https://doi.org/10.21037/tcr.2018.01.30
  6. Oliai C, et al. Stereotactic body radiation therapy for the primary treatment of localized prostate cancer. J. Radiat. Oncol. 2013;2(1):63-70. https://doi.org/10.1007/s13566-012-0067-2
  7. Lischalk JW, Kaplan ID, Collins SP. Stereotactic body radiation therapy for localized prostate cancer. Cancer. J. 2016;22(4):307-313. https://doi.org/10.1097/PPO.0000000000000209
  8. Henderson D, Tree A, Van As N. Stereotactic body radiotherapy for prostate cancer. Clin. Oncol. 2015;27(5):270-279. https://doi.org/10.1016/j.clon.2015.01.011
  9. Musunuru HB, Quon H, Davidson M, Cheung P, Zhang L, D'Alimonte L, Deabreu A, Mamedov A, Loblaw A. Dose-escalation of five-fraction SABR in prostate cancer: Toxicity comparison of two prospective trials. Radiother. Oncol. 2016;118(1):112-117. https://doi.org/10.1016/j.radonc.2015.12.020
  10. Folkert MR, Timmerman RD. Stereotactic ablative body radiosurgery (SABR) or stereotactic body radiation therapy (SBRT). Adv. Drug. Del. Rev. 2017;109(15):3-14. https://doi.org/10.1016/j.addr.2016.11.005
  11. Mutic S, Dempsey JF. The ViewRay system: Magnetic resonanceguided and controlled radiotherapy. Semin. Radiat. Oncol. 2014;24(3):196-199. https://doi.org/10.1016/j.semradonc.2014.02.008
  12. Saenz DL, Paliwal BR, Bayouth JE. A dose homogeneity and conformity evaluation between ViewRay and pinnacle-based linear accelerator IMRT treatment plans. J. Med. Phys. 2014;39(2):64-70. https://doi.org/10.4103/0971-6203.131277
  13. Wooten HO, Rodriguez V, Green O, Kashani R, Santanam L, Tanderup K, Mutic S, Li HH. Benchmark IMRT evaluation of a Co-60 MRI-guided radiation therapy system. Radiother. Oncol. 2015;114(3):402-405. https://doi.org/10.1016/j.radonc.2015.01.015
  14. Kirkby C, Stanescu T, Rathee S, Carlone M, Murray B, Fallone B. Patient dosimetry for hybrid MRI‐radiotherapy systems. Med. Phys. 2008;35(3):1019-1027. https://doi.org/10.1118/1.2839104
  15. Bol G, Lagendijk J, Raaymakers B. Compensating for the impact of non-stationary spherical air cavities on IMRT dose delivery in transverse magnetic fields. Phys. Med. Biol. 2015;60(2):755-768. https://doi.org/10.1088/0031-9155/60/2/755
  16. Raaijmakers A, Raaymakers BW, Lagendijk JJ. Magnetic-fieldinduced dose effects in MR-guided radiotherapy systems: dependence on the magnetic field strength. Phys. Med. Biol. 2008;53(4):909-923. https://doi.org/10.1088/0031-9155/53/4/006
  17. Esmaeeli A, Pouladian M, Monfared A, Mahdavi S, Moslemi D. Effect of uniform magnetic field on dose distribution in the breast radiotherapy. Int. J. Radiat. Res. 2014;12(2):161-170.
  18. Kim JI, Park SY, Lee YH, Shin KH, Wu HG, Park JM. Effect of low magnetic field on dose distribution in the partial-breast irradiation. Prog. Med. Phys. 2015;26(4):208-214. https://doi.org/10.14316/pmp.2015.26.4.208
  19. Son J, Chun M, An HJ, Kang SH, Chie EK, Yoon J, Choi CH, Park JM, Kim JI. Effect of low magnetic field on dose distribution in the SABR plans for liver cancer. Prog. Med. Phys. 2018;29(2):47-52. https://doi.org/10.14316/pmp.2018.29.2.47