Changes in Lung Perfusion Distribution Due to Radiation in Lung Cancer Patients Treated with 3D Conformal Radiation Therapy and Stereotactic Body Radiation Therapy

Abstract

Purpose: To compare correlations between radiation and perfusion damage in lung cancer patients treated with 3D conformal radiation therapy (CRT) (both radical and palliative intent) and stereotactic body radiation therapy (SBRT).

Materials/Methods: Thirteen non-small cell lung cancer patients receiving radiation therapy were included in this study. Eight of them were treated using 3D-CRT with palliative or radical intent (prescription doses 30~43Gy and 50~63Gy respectively, conventional fractionation). Five patients were treated with SBRT (prescription dose is 48Gy to the edge of the PTV in 4 fractions). Perfusion single-photon emission tomography (SPECT) scans using 99mTc were performed before RT and 2~3 months after RT. These scans were used to assess the change in lung perfusion, i.e. blood flow, as an effect of radiation on the normal lung during RT. Dose and corresponding percentage reduction in the SPECT intensity were used to establish dose-response curves (DRC).

Results: Large inter-patient variation in dose-response of lung perfusion was found in all three groups. Reperfusion was common, especially in patients treated with palliative CRT. Meaningful DRC for perfusion change after RT cannot be established in this group. Meanwhile the dose-response in radical CRT and SBRT groups was pronounced and DRC were consistent. DRC from these two groups indicates about 1% reduction in lung perfusion per Gy in total dose delivered to the lung, irrespective of dose per fraction.