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Regional dose response to pulmonary irradiation using a manual method
B Levinson1, L B Marks, M T Munley
1Department of Radiation Oncology, Duke University Medical Center, Durham, NC 27710, USA.
Summary
This study manually assessed radiation therapy effects on lung perfusion and density. Results show increased density and decreased perfusion with higher radiation doses, validating automated methods.
Area of Science:
- Radiology
- Radiation Oncology
- Pulmonary Medicine
Background:
- Radiation therapy (RT) can cause changes in lung tissue.
- Accurate assessment of these changes is crucial for treatment planning.
- Automated methods for assessing RT-induced lung changes may have inaccuracies.
Purpose of the Study:
- To understand radiation therapy dose-dependent changes in regional lung perfusion and tissue density.
- To refine accuracy by using a manual assessment method.
- To compare manual findings with previously automated methods.
Main Methods:
- Prospective study of patients receiving thoracic RT.
- Comparison of pre- and post-RT single photon emission computed tomography (SPECT) and computed tomography (CT) scans.
- Manual definition of study volumes and correlation of 3D dose distribution with imaging data.
Main Results:
- Increased lung tissue density observed with higher regional radiation doses (>60 Gy).
- Decreased regional lung perfusion with increasing radiation dose; a 35% average increase in low-dose regions.
- Manual and automated dose-response data showed good correlation.
- Markedly reduced perfusion at CT densities outside the normal lung range (-600 to -900 H).
Conclusions:
- Manual CT density and perfusion dose-response data align well with automated methods, confirming their accuracy.
- Regional lung perfusion is significantly reduced in areas with CT density outside the normal range.
- Manual assessment provides reliable data for understanding RT-induced lung changes.