Monitoring the hepatic function of unresectable liver cancer patients evaluated by ^99mTc-labeled iminodiacetic acid (HIDA) used with single-photon emission computed tomography (SPECT) imaging before and during radiation therapy provides critical data that could guide more customized treatment plans and reduce risks of liver injury, according to recent research.

The study’s findings were presented at the 2013 Cancer Imaging and Radiation Therapy Symposium, held February 8–9, 2013, in Orlando (FL, USA). This Symposium is sponsored by the American Society for Radiation Oncology (ASTRO; Fairfax, VA, USA) and the Radiological Society of North American (RSNA; Oak Brook, IL, USA). This research included 14 patients who had unresectable intrahepatic tumors and were treated with three-dimensional conformal radiation therapy (3D CRT), intensity-modulated radiation therapy (IMRT) or stereotactic body radiation therapy (SBRT) at a median dose of 52 Gy. Patients underwent HIDA SPECT scanning prior to radiation therapy, after delivery of 50%–60% of the planned doses and one month after completion of radiation therapy. Moreover, indocyanine green tests, a measure of overall liver function, were performed +/- one day of each SPECT scan. The 27 dynamic HIDA SPECT volumes were captured over a 60-minute period after the administration of 10 mCi ^99mTc-labeled HIDA on a SPECT/CT scanner.

Gauging the regional liver function prior to radiation therapy allows assessment of the precondition of the patient’s liver function. Assessing the change of the regional liver function during the mid-course of radiation therapy indicates the response of the individual patient’s liver to radiation doses. Integrating the planned radiation doses with the regional liver function evaluation and reassessment, the researchers devised a model to predict the regional liver function postradiation therapy. This information is key to providing patients with the optimal radiation doses for better tumor control, while minimizing the risk for each patient.

“Through this assessment method, patients could potentially receive more treatment doses tailored to meet their needs, based on their liver function,” said Hesheng Wang, PhD, the lead study author and a postdoctoral fellow in radiation oncology at the University of Michigan in (Ann Arbor, MI, USA). “The physiological adaptation of radiation therapy based upon individual response assessment is a valuable new paradigm worth additional testing.”

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