Monte Carlo study on secondary neutrons in passive carbon-ion radiotherapy: Identification of the main source and reduction in the secondary neutron dose

Abstract New technique is trending in spatially fractionated radiotherapy with protons to utilize the spot scanning together with a physical collimator to obtain minibeams. The primary goal of this study is to quantify ambient neutron dose equivalent (${H}^{\ast }(10)$) due to the secondary neutrons when physical collimator is used to achieve desired minibeams. The ${H}^{\ast }(10)$ per treatment proton dose (D) was assessed using Monte Carlo code TOPAS and measured using WENDI-II detector at different angles (135, 180, 225 and 270 degrees) and distances (11 cm, 58 and 105 cm) from the phantom for two cases: with and without physical collimation. Without collimation $\frac{H^{\ast }(10)}{D}$ varied from 0.0013 to 0.242 mSv/Gy. With collimation $\frac{H^{\ast }(10)}{D}$ varied from 0.017 to 3.23 mSv/Gy. Results show that the secondary neutron dose will increase tenfold when the physical collimator is used. Regardless, it will be low and comparable to the neutron dose produced by conventional passive-scattered proton beams.

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SU-E-T-495: Influence of Reduced Target-To-Nozzle Distance On Secondary Neutron Dose Equivalent in Proton and Carbon Ion Radiotherapy

Medical Physics ◽

10.1118/1.4924857 ◽

2015 ◽

Vol 42 (6Part20) ◽

pp. 3448-3448

Author(s):

Y Sheng ◽

K Shahnazi ◽

W Wang ◽

M Moyers ◽

Y Deng ◽

...

Keyword(s):

Neutron Dose ◽

Carbon Ion Radiotherapy ◽

Dose Equivalent ◽

Secondary Neutron ◽

Carbon Ion ◽

Neutron Dose Equivalent

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Monte Carlo study of out‐of‐field exposure in carbon‐ion radiotherapy: Organ doses in pediatric brain tumor treatment

Medical Physics ◽

10.1002/mp.13864 ◽

2019 ◽

Vol 46 (12) ◽

pp. 5824-5832

Author(s):

Shinnosuke Matsumoto ◽

Shunsuke Yonai ◽

Wesley E. Bolch

Keyword(s):

Monte Carlo ◽

Brain Tumor ◽

Pediatric Brain Tumor ◽

Monte Carlo Study ◽

Carbon Ion Radiotherapy ◽

Tumor Treatment ◽

Field Exposure ◽

Organ Doses ◽

Carbon Ion ◽

Pediatric Brain

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Monte Carlo study of out-of-field exposure in carbon-ion radiotherapy with a passive beam: Organ doses in prostate cancer treatment

Physica Medica ◽

10.1016/j.ejmp.2018.04.391 ◽

2018 ◽

Vol 51 ◽

pp. 48-55 ◽

Cited By ~ 8

Author(s):

Shunsuke Yonai ◽

Naruhiro Matsufuji ◽

Keiichi Akahane

Keyword(s):

Prostate Cancer ◽

Monte Carlo ◽

Cancer Treatment ◽

Monte Carlo Study ◽

Carbon Ion Radiotherapy ◽

Prostate Cancer Treatment ◽

Field Exposure ◽

Organ Doses ◽

Carbon Ion

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A preliminary Monte Carlo study for the treatment head of a carbon-ion radiotherapy facility using TOPAS

EPJ Web of Conferences ◽

10.1051/epjconf/201715304018 ◽

2017 ◽

Vol 153 ◽

pp. 04018

Author(s):

Hongdong Liu ◽

Lian Zhang ◽

Zhi Chen ◽

Xinguo Liu ◽

Zhongying Dai ◽

...

Keyword(s):

Monte Carlo ◽

Monte Carlo Study ◽

Carbon Ion Radiotherapy ◽

Carbon Ion

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EVALUATION OF NEUTRON AMBIENT DOSE EQUIVALENT IN CARBON-ION RADIOTHERAPY WITH ENERGY SCANNING

Radiation Protection Dosimetry ◽

10.1093/rpd/ncaa166 ◽

2020 ◽

Vol 191 (3) ◽

pp. 310-318

Author(s):

Shinnosuke Matsumoto ◽

Shunsuke Yonai

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Carbon Ion Radiotherapy ◽

Neutron Energy Spectrum ◽

Dose Equivalent ◽

Realistic Case ◽

Carbon Ion ◽

Ambient Dose Equivalent ◽

Secondary Neutrons ◽

Ambient Dose

Abstract In carbon-ion radiotherapy (CIRT), secondary neutrons are produced by nuclear interactions in the beamline devices or patient. Herein, the characteristics of secondary neutrons in CIRT with energy scanning (ES) were evaluated. Neutron ambient dose equivalents (H*(10)) were measured using WENDI-II. The neutron energy spectrum was calculated using the Monte Carlo simulation. Measurement and calculation were performed under realistic case scenarios using maximum beam energies (Emax) of 290, 350 and 400 MeV u −1. Moreover, H*(10) in ES was compared with H*(10) in range-shifter scanning (RS) and hybrid scanning (HS). H*(10) in Emax = 290 MeV u−1 was 65% less than that in Emax = 400 MeV u−1. At Emax = 350 MeV u−1, H*(10) in ES at θ = 120 was 42% of that at θ = 60. The neutron dose in ES CIRT decreased to approximately 60 and 70% of that in RS and HS CIRT, respectively, at 50-cm distance from the beam axis.

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