Table 4.

Estimation of the total neutron H to the fetus with passive scattering beam.

$H/D$ for 15 cm Proton Range (mSv/Gy)	13 cm SOBP Factor	Snout Position Factor	$4\times 4\hspace{0.17em}c{m}^2$ Field Size Factor	Estimation (mSv/Gy)	Estimation in 70 Gy (mSv)
0.50	2	1	1	1	70

$\text{SOBP}=\text{spread}‐\text{out Bragg peak}$.