Feasibility of Using Real-time Cine-MRI for Treating Moving & Deforming Tumors

Accurate dose delivery remains one of the weakest aspects of radiotherapy, especially in the
case of thoracic and abdominal tumors, where significant patient motion occurs during dose
delivery (intrafraction motion). Such motion results in geometric and dosimetric
uncertainties that compromise treatment quality. Effective management of intrafraction
motion is therefore key to realizing the full potential of modern image-guided radiation
therapy (IGRT). While external markers have been found to be well-correlated with internal
anatomy within an imaging session, there is no guarantee that these correlations will
continue to exist and be constant throughout the course of the therapy. In general,
implanted, radio-opaque seeds have been found to be more reliable than external markers.
However, implantation of fiducials, whether radio-opaque or electromagnetic, is necessarily
invasive and carries with it the risk of associated complications ─ an issue that
becomes especially important for cancer patients with weakened immune systems. Currently, MR
imaging is the only modality that is non-invasive and provides high quality volumetric
information for the whole body.

The "ideal" intrafraction motion management requires complete spatio-temporal knowledge of
the irradiated anatomy. However, to date, there is no clinical method of directly
visualizing the tumor volume during dose delivery. Most techniques rely on external or
internal surrogate markers which often provide (usually non-volumetric) information of
limited accuracy and reliability. In addition, internal markers impose significant "costs"
on the patient in terms of interventional complications and increased imaging dose. In this
work, we investigate the feasibility of using in-room, fast cine MR imaging as a
non-invasive means to provide real-time, soft-tissue-based, volumetric image guidance for
continuous monitoring of the target and surrounding anatomy. To date, there has been no
systematic investigation of the imaging requirements of an integrated MRI+linac for the
specific task of real-time radiotherapy guidance.

Inclusion Criteria:3.1.1. Eligible disease(s)/stage(s) AJCC Stage I, II,
III or IV lung, liver or pancreatic cancer of any histology to be treated using
radiotherapy will be eligible for this study.

3.1.2. Allowable type and amount of prior therapy  Any types and amounts of prior
therapy will be allowed for this study.

3.1.3. Age restriction and/or gender/ethnic restrictions Patients must be
greater than or equal to 18 years of age. There are no gender or ethnic restrictions.

3.1.4. Life expectancy restrictions  None.

3.1.5. ECOG or Karnofsky Performance Status  Karnofsky performance status of 50 or
greater

3.1.6. Requirements for organ and marrow function  None.

3.1.7. Ability to understand and the willingness to sign a written informed consent
document.

3.1.8. Pain-free in supine position

Exclusion Criteria:3.2.1 Children (age <18)

3.2.2 Metallic implants, embedded metallic objects, implanted biomedical devices e.g.,
cardiac pacemakers

3.2.3 Women who are pregnant or trying to get pregnant

3.2.4 Pain in supine position

3.2.5 Karnofsky performance status < 50