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Quantifying lateral penumbra advantages of collimated spot-scanning beam for intensity-modulated proton therapy

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Abstract

Intensity-modulated proton therapy (IMPT) is becoming essential for proton therapy and is under rapid development. However, for IMPT, the lateral penumbra of the spot-scanning proton beam is still an urgent issue to be solved. Patient-specific block collimators (PSBCs), which can block unnecessary doses, play a crucial role in passive scattering delivery technology but are rarely used in spot scanning. One objective of this study is to investigate the lateral penumbra variations of intensity-modulated spot scanning with and without a PSBC. For fields with varying degrees of sharpness and at varying depths in a water phantom, the lateral penumbral widths were calculated using a Monte Carlo-based dose engine from RayStation 6. The results suggest that the lateral penumbral widths can be reduced by more than 30% for uniform target volumes, regardless of whether a range-shifter is used, and that the maximum dose beyond the field edges can be reduced significantly. The results of patient cases show that the doses in organs-at-risk near the edge of the target volume decrease if a PSBC is implemented. This study demonstrates that intensity-modulated spot scanning with a PSBC can effectively reduce the lateral penumbra and block unnecessary doses and is therefore promising for clinical applications in spot-scanning proton therapy.

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Authors and Affiliations

  1. University of Science and Technology of China, Hefei, 230026, China

    Chun-Bo Liu, Yun-Tao Song & Hong-Dong Liu

  2. Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China

    Yun-Tao Song & Han-Sheng Feng

  3. Hefei CAS Ion Medical and Technical Devices Co., Ltd, Hefei, 230088, China

    Hai-Zhou Xue

Authors
  1. Chun-Bo Liu
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  2. Yun-Tao Song
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  3. Hong-Dong Liu
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  4. Hai-Zhou Xue
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  5. Han-Sheng Feng
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Correspondence to Han-Sheng Feng.

Additional information

This work was supported by the Key Program of the 13th Five-Year Plan, the Hefei Institutes of Physical Science of the Chinese Academy of Sciences (No. KP-2017-24).

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Liu, CB., Song, YT., Liu, HD. et al. Quantifying lateral penumbra advantages of collimated spot-scanning beam for intensity-modulated proton therapy. NUCL SCI TECH 30, 168 (2019). https://doi.org/10.1007/s41365-019-0687-y

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  • DOI: https://doi.org/10.1007/s41365-019-0687-y

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