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

Journal Article · Fri Jan 01 00:00:00 EST 2010 · Medical Dosimetry

DOI:https://doi.org/10.1016/j.meddos.2009.09.004· OSTI ID:21486873

Hodge, C W ^[1]; Fain, S B ^[2]; Bentzen, S M ^[1]; Mehta, M P ^[1]

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1. Department of Human Oncology, University of Wisconsin, Madison, WI (United States)
2. Department of Medical Physics, University of Wisconsin, Madison, WI (United States)

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 (PD{sub w}) 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 (f{sub dam}) 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 (NTD{sub mean}) values for the lung subvolumes were: lungs = 12.5 Gy{sub 3}vs. 13.52 Gy{sub 3}, VV = 9.94 Gy{sub 3}vs. 13.95 Gy{sub 3}, and lungs minus VV = 16.69 Gy{sub 3}vs. 19.16 Gy{sub 3}. Using the f{sub dam} 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.

• OSTI ID: 21486873
• Journal Information: Medical Dosimetry, Vol. 35, Issue 4; Other Information: DOI: 10.1016/j.meddos.2009.09.004; PII: S0958-3947(09)00094-6; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0958-3947
• Country of Publication: United States
• Language: English

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62 RADIOLOGY AND NUCLEAR MEDICINE
COMPUTERIZED TOMOGRAPHY
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PNEUMONITIS
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DIAGNOSTIC TECHNIQUES
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