Tumor Motion and Dosimetry Variability Based on 4DMRI in Comparison with 4DCT

Abstract

locations; Dose to the prostate and pelvic node CTVs, rectum, bladder and femoral heads were calculated and presented for the total 20 plan scenarios of each patient. Results: For bony matching, prostate CTV dose degradation was prominent for interfraction prostate motion beyond prostate PTV margins. Potential prostate intrafraction motion would further degrade the prostate CTV coverage. Lymph node CTV dose coverages were not affected; for seed matching, dose degradation of pelvic lymph node CTV was prominent for interfraction prostate motion beyond pelvic node PTV margins. Dose coverage to prostate CTV were comparable to original treatment plans. For the seed matching image guidance, there were large dose variations to the rectum, bladder and femoral head among different prostate interfraction motion datasets. For the bony matching image guidance, there were large dose variations only to the rectum among different prostate interfraction motion datasets. Conclusion: Prostate interfraction motion from pelvic lymph node has significant impact on prostate and lymph node CTVs coverage. Due to this motion, different image guidance approach affect the target coverage and dose to OARs in a different manner.

Respiratory-Correlated (RC) vs. Time-Resolved (TR) Four-Dimensional Magnetic Resonance Imaging (4DMRI) for Radiotherapy of Thoracic and Abdominal Cancer

“…Kontaxis et al reported a strategy to perform online intrafraction replanning for free-breathing stereotactic body radiation therapy using MRL (54). The dosimetry consequence of motion variation from treatment planning viewpoint was studied using RC- and TR-4DMRI, in comparison with the ITV method based on 4DCT (55). Substantial dosimetry variations in ITV-based planning were found when the tumor motion range varied by 5 mm, and this is worthwhile for further evaluations.…”