Multi-layer energy filter for realizing conformal irradiation in charged particle therapy

Takeji Sakae, Akihiro Nohtomi, Akira Maruhashi, Masaru Sato, Toshiyuki Terunuma, Ryosuke Kohno, Yasuyuki Akine, Yoshinori Hayakawa, Yasunori Koike

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)


A new type of filter for charged particle radiotherapy is developed to reduce unwanted dose transfer to the normal tissues around a tumor. The new filter can make a static irradiation field where the width of the spread-out Bragg peak (SOBP) is two-dimensionally adjusted. That makes the field conformal to the tumor three-dimensionally. The filter is made of many layers produced by using stereolithography. The layer has a miniaturized structure that has geometrical similarity to the conventional ridge filter. Shapes of cone and pyramid are also usable for the unit-cell constructing the layer. The spread of the field in the depth direction is decided by the thickness of the filter, or by the number of layers. The experimental result of the irradiation using the ridge-type construction shows a good agreement with an estimate by the Monte Carlo calculation. By combining this technique with intensity modulation that has lateral position dependence, the conformal irradiation can be achieved by a simple procedure. (C) 2000 American Association of Physicists in Medicine.

Original languageEnglish
Pages (from-to)368-373
Number of pages6
JournalMedical physics
Issue number2
Publication statusPublished - Feb 2000
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Radiology Nuclear Medicine and imaging


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