Affiliations: Radiation Oncology, Washington University, St. Louis,
MO, USA | Nuclear Science and Engineering Institute, University
of MO, Columbia, MO, USA | Radiation Oncology, Baylor Scott and White Health,
Temple, TX, USA
Note: [] Corresponding author: Enrique W. Izaguirre, 2401 South 31st
Street, MS-09-C011, Temple, TX 76508, USA. Tel.: +1 254 724 0441; Fax: +1 254
724 6061; E-mail: eizaguirre@sw.org
Abstract: Image guided conformal small animal orthovoltage microirradiators
are currently under development to perform radiobiological experiments with
preclinical cancer models. An important component of these instruments is the
treatment delivery image guidance system, a microelectronic portal imaging
device (μEPID). Here, we present the design and implementation of a μEPID,
specifically designed and constructed for small animal orthovoltage
microirradiators. The μEPID can acquire images in the range of 60 kVp to
320 kVp x-ray photon energies and can endure high doses from orthovoltage beams
without radiation damage. The μEPID can acquire 200 μm resolution
images at a rate of 17 frames per second for online in vivo co-registration
between irradiation beams and small animal anatomy. An exposure with less than
1% of a 2 Gy treatment field is required for imaging, which is an adequate
ratio between imaging dose and treatment dose to avoid undesired irradiation of
healthy tissue or alteration of the preclinical cancer model. The μEPID
was calibrated for microdosimetry with a precision of 4.1% with respect to
an ion chamber, used as a gold standard. To validate the in vivo
device performance, irradiations of lung, brain, and xenograft breast cancer
preclinical models were performed and analyzed.
Keywords: Preclinical radiobiology, microirradiator, high resolution imaging, orthovoltage imaging
