The biological effectiveness of antiproton irradiation

Michael H. Holzscheiter, Niels Bassler, Nzhde Agazaryan, Gerd Beyer, Ewart Blackmore, John J. DeMarco, Michael Doser, Ralph E. Durand, Oliver Hartley, Keisuke S. Iwamoto, Helge V. Knudsen, Rolf Landua, Carl Maggiore, William H. McBride, Søren Pape Møller, Jørgen Petersen, Lloyd D. Skarsgard, James B. Smathers, Timothy D. Solberg, Ulrik I. UggerhøjSanja Vranjes, H. Rodney Withers, Michelle Wong, Bradly G. Wouters

Research output: Contribution to journalArticlepeer-review

55 Scopus citations


Background and purpose: Antiprotons travel through tissue in a manner similar to that for protons until they reach the end of their range where they annihilate and deposit additional energy. This makes them potentially interesting for radiotherapy. The aim of this study was to conduct the first ever measurements of the biological effectiveness of antiprotons. Materials and methods: V79 cells were suspended in a semi-solid matrix and irradiated with 46.7 MeV antiprotons, 48 MeV protons, or 60Co γ-rays. Clonogenic survival was determined as a function of depth along the particle beams. Dose and particle fluence response relationships were constructed from data in the plateau and Bragg peak regions of the beams and used to assess the biological effectiveness. Results: Due to uncertainties in antiproton dosimetry we defined a new term, called the biologically effective dose ratio (BEDR), which compares the response in a minimally spread out Bragg peak (SOBP) to that in the plateau as a function of particle fluence. This value was ∼3.75 times larger for antiprotons than for protons. This increase arises due to the increased dose deposited in the Bragg peak by annihilation and because this dose has a higher relative biological effectiveness (RBE). Conclusion: We have produced the first measurements of the biological consequences of antiproton irradiation. These data substantiate theoretical predictions of the biological effects of antiproton annihilation within the Bragg peak, and suggest antiprotons warrant further investigation.

Original languageEnglish (US)
Pages (from-to)233-242
Number of pages10
JournalRadiotherapy and Oncology
Issue number3
StatePublished - Dec 2006


  • Antiproton
  • High LET
  • Particle irradiation
  • RBE

ASJC Scopus subject areas

  • Hematology
  • Oncology
  • Radiology Nuclear Medicine and imaging


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