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Son, Chun, An, Kang, Chie, Yoon, Choi, Park, and Kim: Effect of Low Magnetic Field on Dose Distribution in the SABR Plans for Liver Cancer
Original Article

Progress in Medical Physics 2018;29(2):47-52.

Published online: 20 June 2018

DOI: https://doi.org/10.14316/pmp.2018.29.2.47

Effect of Low Magnetic Field on Dose Distribution in the SABR Plans for Liver Cancer

Jaeman Son∗, Minsoo Chun∗, Hyun Joon An∗, Seong-Hee Kang†, Eui Kyu Chie∗, ‡, §, ΙΙ, Jeongmin Yoon∗, Chang Heon Choi∗, Jong Min Park∗, ‡, §, , Jung-in Kim∗, ‡, §

∗Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea

†Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam, Korea

‡Biomedical Research Institute, Seoul National University Hospital,

§Institute of Radiation Medicine, Seoul National University Medical Research Center, Seoul, Korea

ΙΙDepartment of Radiation Oncology, Seoul National University College of Medicine, Seoul, Korea

Center for Convergence Research on Robotics, Advanced Institutes of Convergence Technology, Suwon, Korea

Corresponding author Jung-in Kim (madangin@gmail.com) Tel: 82-2-2072-3573 Fax: 82-2-765-3317

Received 24 May 2018       Revised 20 May 2018       Accepted 21 May 2018

Copyright © 2018 Korean Society of Medical Physics

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

To investigate the effect of low magnetic field on dose distribution in SABR plans for liver cancer, we calculated and evaluated the dose distribution to each organ with and without magnetic fields. Ten patients received a 50 Gy dose in five fractions using the ViewRay® treatment planning system. For planning target volume (PTV), the results were analyzed in the point minimum (Dmin), maximum (Dmax), mean dose (Dmean) and volume receiving at least 90% (V90%), 95% (V95%), and 100% (V100%) of the prescription dose, respectively. For organs at risk (OARs), the duodenum and stomach were analyzed with D0.5cc and D2cc, and the remained liver except for PTV was analyzed with Dmean, Dmax, and Dmin. Both inner and outer shells were analyzed with the point Dmin, Dmax, and Dmean, respectively. For PTV, the maximum change in volume due to the presence or absence of the low magnetic field showed a percentage difference of up to 0.67±0.60%. In OAR analysis, there is no significant difference for the magnetic field. In both shell structure analyses, although there are no major changes in dose distribution, the largest value of deviation for Dmax in the outer shell is 2.12±2.67 Gy. The effect of low magnetic field on dose distribution by a Co-60 beam was not significantly observed within the body, but the dose deposition was only appreciable outside the body.

Keywords: Liver cancer, SABR, MR-IGRT, Magnetic field

References

1. Torre LA, Bray F, Siegel RL, Ferlay J, Lortet‐Tieulent J, Jemal A. Global cancer statistics, 2012. CA: a cancer journal for clinicians. 2015; 65(2):87–108.
crossref
2. Huang K, Dahele M, Senan S, et al. Radiographic changes after lung stereotactic ablative radiotherapy (SABR)-can we distinguish recurrence from fibrosis? A systematic review of the literature. Radiotherapy and Oncology. 2012; 102(3):335–42.
3. Finkelstein SE, Timmerman R, Mcbride WH, et al. The confluence of stereotactic ablative radiotherapy and tumor immunology. Clinical and Developmental Immunology. 2011; 2011.
crossref
4. Myrehaug S, Sahgal A, Russo SM, et al. Stereotactic body radiotherapy for pancreatic cancer: recent progress and future directions. Expert review of anticancer therapy. 2016; 16(5):523–30.
crossref
5. Pidikiti R, Stojadinovic S, Speiser M, et al. Dosimetric characterization of an imageguided stereotactic small animal irradiator. Physics in Medicine & Biology. 2011; 56(8):2585.
crossref
6. Palma DA, Haasbeek CJ, Rodrigues GB, et al. Stereotactic ablative radiotherapy for comprehensive treatment of oligometastatic tumors (SABR-COMET): study protocol for a randomized phase II trial. BMC cancer. 2012; 12(1):305.
crossref
7. Mutic S, Dempsey JF. The ViewRay system: Magnetic resonance-guided and controlled radiotherapy. Seminars in radiation oncology: Elsevier. 2014. 196–99.
crossref
8. Yang Y, Cao M, Sheng K, et al. Longitudinal diffusion MRI for treatment response assessment: Preliminary experience using an MRI‐guided tri‐cobalt 60 radiotherapy system. Medical physics. 2016; 43(3):1369–73.
crossref
9. Wooten HO, Rodriguez V, Green O, et al. Benchmark IMRT evaluation of a Co-60 MRI-guided radiation therapy system. Radiotherapy and Oncology. 2015; 114(3):402–5.
crossref
10. Burke B, Ghila A, Fallone B, Rathee S. Radiation induced current in the RF coils of integrated linac‐MR systems: The effect of buildup and magnetic field. Medical physics. 2012; 39(8):5004–14.
crossref
11. Rubinstein AE, Liao Z, Melancon AD, et al. A Monte Carlo study of magnetic‐field‐induced radiation dose effects in mice. Medical physics. 2015; 42(9):5510–16.
12. Kirkby C, Stanescu T, Fallone B. Magnetic field effects on the energy deposition spectra of MV photon radiation. Physics in Medicine & Biology. 2008; 54(2):243.
crossref
13. Raaijmakers AJ, Raaymakers BW, Lagendijk JJ. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: dose increase at tissue-air interfaces in a lateral magnetic field due to returning electrons. Phys Med Biol. 2005; 50(7):1363–76.
crossref
14. Raaijmakers AJ, Raaymakers BW, Van Der Meer S, Lagendijk JJ. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: impact of the surface orientation on the entrance and exit dose due to the transverse magnetic field. Phys Med Biol. 2007; 52(4):929–39.
crossref
15. Kim JI, Park SY, Lee YH, Shin KH, Wu H-G, Park JM. Effect of low magnetic field on dose distribution in the partial-breast irradiation. Progress in Medical Physics. 2015; 26(4):208–14.
crossref
16. Esmaeeli A, Pouladian M, Monfared A, Mahdavi S, Mosle-mi D. Effect of uniform magnetic field on dose distribution in the breast radiotherapy. International Journal of Radiation Research. 2014; 12(2):161.

Fig. 1.
The comparison of dose distribution (a) with magnet and (b) without magnet field in the case of liver SABR with a magnet field (B0).
pmp-29-47f1.tif
Fig. 2.
Dose and volume difference values in PTV for each patient.
pmp-29-47f2.tif
Fig. 3.
The dose distribution in sagittal image between (a) with magnet field (B0) and (b) without magnet field.
pmp-29-47f3.tif
Table 1.
The average dosimetric parameter analysis for PTV.
Analysis With Magnet Without Magnet Difference value P-value
Dmean (Gy) 52.42±1.19 52.44±1.15 0.07±0.05 0.22
Dmax (Gy) 55.99±2.43 55.89±2.20 0.30±0.25 0.31
Dmin (Gy) 45.98±1.11 46.05±1.19 0.28±0.33 0.21
V90% (%) 99.99±0.04 99.99±0.04 0.00±0.00 0.50
V95% (%) 99.65±0.29 99.66±0.30 0.05±0.04 0.26
V100% (%) 90.54±8.07 90.64±7.77 0.67±0.60 0.37
Table 2.
The average dosimetric parameter analysis for organs at risk (OARs).
OARs Analysis With Magnet Without Magnet Difference value P-value
Duodenum D0.5cc (Gy) 7.01±7.93 7.00±7.92 0.05±0.05 0.40
D2cc (Gy) 5.23±5.24 5.25±5.25 0.06±0.04 0.29
Stomach D0.5cc (Gy) 12.81±7.26 12.56±7.53 0.31±0.69 0.19
D2cc (Gy) 11.35±6.78 11.28±6.87 0.12±0.18 0.18
Remained normal liver Dmean (Gy) 11.12±2.53 11.13±2.54 0.01±0.01 0.16
Dmax (Gy) 52.46±1.70 52.32±1.55 0.33±0.36 0.16
Dmin (Gy) 0.50±0.21 0.48±0.19 0.03±0.03 0.19
Table 3.
The average dosimetric parameter analysis for shell structures.
  Analysis With Magnet Without Magnet Difference value P-value
Inner shell Dmean (Gy) 1.34±0.53 1.35±0.52 0.02±0.02 0.21
Dmax (Gy) 31.49±4.82 31.97±4.78 0.59±0.92 0.09
Dmin (Gy) 0.02±0.01 0.02±0.01 0.00±0.00 0.50
Outer shell Dmean (Gy) 1.00±0.38 0.98±0.34 0.08±0.07 0.34
Dmax (Gy) 21.14±3.75 22.29±4.07 2.12±2.67 0.16
Dmin (Gy) 0.02±0.01 0.02±0.01 0.00±0.00 0.30
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