Prompt Gamma Imaging for In Vivo Range Verification of Pencil Beam Scanning Proton Therapy

Yunhe Xie, El Hassane Bentefour, Guillaume Janssens, Julien Smeets, François Vander Stappen, Lucian Hotoiu, Lingshu Yin, Derek Dolney, Stephen Avery, Fionnbarr O'Grady, Damien Prieels, James McDonough, Timothy D. Solberg, Robert A. Lustig, Alexander Lin, Boon Keng K. Teo

Research output: Contribution to journalArticlepeer-review

123 Scopus citations


Purpose To report the first clinical results and value assessment of prompt gamma imaging for in vivo proton range verification in pencil beam scanning mode. Methods and Materials A stand-alone, trolley-mounted, prototype prompt gamma camera utilizing a knife-edge slit collimator design was used to record the prompt gamma signal emitted along the proton tracks during delivery of proton therapy for a brain cancer patient. The recorded prompt gamma depth detection profiles of individual pencil beam spots were compared with the expected profiles simulated from the treatment plan. Results In 6 treatment fractions recorded over 3 weeks, the mean (± standard deviation) range shifts aggregated over all spots in 9 energy layers were −0.8 ± 1.3 mm for the lateral field, 1.7 ± 0.7 mm for the right-superior-oblique field, and −0.4 ± 0.9 mm for the vertex field. Conclusions This study demonstrates the feasibility and illustrates the distinctive benefits of prompt gamma imaging in pencil beam scanning treatment mode. Accuracy in range verification was found in this first clinical case to be better than the range uncertainty margin applied in the treatment plan. These first results lay the foundation for additional work toward tighter integration of the system for in vivo proton range verification and quantification of range uncertainties.

Original languageEnglish (US)
Pages (from-to)210-218
Number of pages9
JournalInternational Journal of Radiation Oncology Biology Physics
Issue number1
StatePublished - Sep 1 2017

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research


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