Feasibility of using megavoltage computed tomography to reduce proton range uncertainty: A simulation study

Yanle Hu, Xiaoning Ding, Jiajian Shen, Martin Bues, Wei Liu, Yixiu Kang, Shuai Leng, Lifeng Yu

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To demonstrate that variation in chemical composition has a negligible effect on the mapping curve from relative electron density (RED) to proton stopping power ratio (SPR), and to establish the theoretical framework of using Megavoltage (MV) computed tomography (CT), instead of kilovoltage (kV) dual energy CT, to accurately estimate proton SPR. Methods: A simulation study was performed to evaluate the effect of chemical composition variation on kVCT number and proton SPR. The simulation study involved both reference and simulated human tissues. The reference human tissues, together with their physical densities and chemical compositions, came from the ICRP publication 23. The simulated human tissues were created from the reference human tissues assuming that elemental percentage weight followed a Gaussian distribution. For all tissues, kVCT number and proton SPR were obtained through (a) theoretical calculation from tissue’s physical density and chemical composition which served as the ground truth, and (b) estimation from RED using the calibration curves established from the stoichiometric method. Deviations of the estimated values from the calculated values were quantified as errors in using RED to estimate kVCT number and proton SPR. Results: Given a chemical composition variation of 5% (1σ) of the nominal percentage weights, the total estimation error of using RED to estimate kVCT number was 0.34%, 0.62%, and 0.77% and the total estimation error of using RED to estimate proton SPR was 0.30%, 0.22%, and 0.16% for fat tissues, non-fat soft tissues and bone tissues, respectively. Conclusion: Chemical composition had a negligible effect on the method of using RED to determine proton SPR. RED itself is sufficient to accurately determine proton SPR. MVCT number maintains a superb linear relationship with RED because it is highly dominated by Compton scattering. Therefore, MVCT has great potential in reducing the proton range uncertainty.

Original languageEnglish (US)
Pages (from-to)131-140
Number of pages10
JournalJournal of applied clinical medical physics
Volume22
Issue number3
DOIs
StatePublished - Mar 2021

Keywords

  • MVCT
  • proton range uncertainty
  • stoichiometric method

ASJC Scopus subject areas

  • Radiation
  • Instrumentation
  • Radiology Nuclear Medicine and imaging

Fingerprint Dive into the research topics of 'Feasibility of using megavoltage computed tomography to reduce proton range uncertainty: A simulation study'. Together they form a unique fingerprint.

Cite this