On the Use of Hyperpolarized Helium MRI for Conformal Avoidance Lung Radiotherapy

C. W. Hodge, Wolfgang A. Tomé, S. B. Fain, S. M. Bentzen, M. P. Mehta

Research output: Contribution to journalArticle

26 Scopus citations

Abstract

We wanted to illustrate the feasibility of using hyperpolarized helium magnetic resonance imaging (HPH-MRI) to obtain functional information that may assist in improving conformal avoidance of ventilating lung tissue during thoracic radiotherapy. HPH-MRI images were obtained from a volunteer patient and were first fused with a proton density-weighted (PDw) MRI to provide corresponding anatomic detail; they were then fused with the treatment planning computed tomography scan of a patient from our treatment planning database who possessed equivalent thoracic dimensions. An optimized treatment plan was then generated using the TomoTherapy treatment planning system, designating the HPH-enhancing regions as ventilation volume (VV). A dose-volume histogram compares the dosimetry of the lungs as a paired organ, the VV, and the lungs minus the VV. The clinical consequences of these changes was estimated using a bio-effect model, the parallel architecture model, or the local damage (fdam) model. Model parameters were chosen from published studies linking the incidence of grade 3+ pneumonitis, with the dose and volume irradiated. For two hypothetical treatment plans of 60 Gy in 30 fractions delivered to a right upper-lobe lung mass, one using and one ignoring the VV as an avoidance structure, the mean normalized total dose (NTDmean) values for the lung subvolumes were: lungs = 12.5 Gy3 vs. 13.52 Gy3, VV = 9.94 Gy3 vs. 13.95 Gy3, and lungs minus VV = 16.69 Gy3 vs. 19.16 Gy3. Using the fdam values generated from these plans, one would predict a reduction of the incidence of grade 3+ radiation pneumonitis from 12%-4% when compared with a conventionally optimized plan. The use of HPH-MRI to identify ventilated lung subvolumes is feasible and has the potential to be incorporated into conformal avoidance treatment planning paradigms. A prospective clinical study evaluating this imaging technique is being developed.

Original languageEnglish (US)
Pages (from-to)297-303
Number of pages7
JournalMedical Dosimetry
Volume35
Issue number4
DOIs
Publication statusPublished - Nov 10 2010
Externally publishedYes

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Keywords

  • Functional imaging
  • Image guidance
  • Lung cancer
  • Magnetic resonance imaging
  • Radiotherapy

ASJC Scopus subject areas

  • Radiological and Ultrasound Technology
  • Oncology
  • Radiology Nuclear Medicine and imaging

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