Assessment of knowledge-based planning for prostate intensity modulated proton therapy

Yihang Xu, Nellie Brovold, Jonathan Cyriac, Elizabeth Bossart, Kyle Padgett, Michael Butkus, Tejan Diwanj, Adam King, Alan Dal Pra, Matt Abramowitz, Alan Pollack, Nesrin Dogan

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Purpose: To assess the performance of a proton-specific knowledge based planning (KBPP) model in creation of robustly optimized intensity-modulated proton therapy (IMPT) plans for treatment of patients with prostate cancer. Materials and Methods: Forty-five patients with localized prostate cancer, who had previously been treated with volumetric modulated arc therapy, were selected and replanned with robustly optimized IMPT. A KBPP model was generated from the results of 30 of the patients, and the remaining 15 patient results were used for validation. The KBPP model quality and accuracy were evaluated with the model-provided organ-at-risk regression plots and metrics. The KBPP quality was also assessed through comparison of expert and KBPP-generated IMPT plans for target coverage and organ-at-risk sparing. Results: The resulting R2 (mean 6 SD, 0.87 6 0.07) between dosimetric and geometric features, as well as the v2 test (1.17 6 0.07) between the original and estimated data, showed the model had good quality. All the KBPP plans were clinically acceptable. Compared with the expert plans, the KBPP plans had marginally higher dose-volume indices for the rectum V65Gy (0.8% 6 2.94%), but delivered a lower dose to the bladder (-1.06% 6 2.9% for bladder V65Gy). In addition, KBPP plans achieved lower hotspot (-0.67Gy 6 2.17Gy) and lower integral dose (-0.09Gy 6 0.3Gy) than the expert plans did. Moreover, the KBPP generated better plans that demonstrated slightly greater clinical target volume V95 (0.1% 6 0.68%) and lower homogeneity index (-1.13 6 2.34). Conclusions: The results demonstrated that robustly optimized IMPT plans created by the KBPP model are of high quality and are comparable to expert plans. Furthermore, the KBPP model can generate more-robust and more-homogenous plans compared with those of expert plans. More studies need to be done for the validation of the proton KBPP model at more-complicated treatment sites.

Original languageEnglish (US)
Pages (from-to)62-72
Number of pages11
JournalInternational Journal of Particle Therapy
Issue number2
StatePublished - Sep 1 2021


  • IMPT
  • Knowledge-based planning
  • Prostate cancer

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging


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