Prog Med Phys.  2018 Jun;29(2):47-52. 10.14316/pmp.2018.29.2.47.

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

• Son J
• Chun M
• An HJ
• Kang SH
• Chie EK
• Yoon J
• Choi CH
• Park JM
• Kim JI

• KMID: 2415902
• DOI: http://doi.org/10.14316/pmp.2018.29.2.47

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 (D(min)), maximum (D(max)), mean dose (D(mean)) and volume receiving at least 90% (V(90%)), 95% (V(95%)), and 100% (V(100%)) of the prescription dose, respectively. For organs at risk (OARs), the duodenum and stomach were analyzed with D(0.5cc) and D(2cc), and the remained liver except for PTV was analyzed with D(mean), D(max), and D(min). Both inner and outer shells were analyzed with the point D(min), D(max), and D(mean), 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 D(max) 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.

Keyword

Liver cancer; SABR; MR-IGRT; Magnetic field

MeSH Terms

Duodenum
Humans
Liver Neoplasms*
Liver*
Magnetic Fields*
Organs at Risk
Prescriptions
Stomach

Figure

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  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).

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  Fig. 2. Dose and volume difference values in PTV for each patient.

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  Fig. 3. The dose distribution in sagittal image between (a) with magnet field (B0) and (b) without magnet field.

Reference

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