Prospective MRI Assessment of Serial Dose-Response Kinetics of Swallowing Muscles in Oropharyngeal Cancer Patients Treated With Radiation Therapy and Correlations With Dynamic Imaging Grade for Swallowing Toxicity (DIGEST)

2017 ◽  
Vol 99 (2) ◽  
pp. E357-E358
Author(s):  
M.A.M. Meheissen ◽  
M. Kamal ◽  
A.S.R. Mohamed ◽  
Y. Ding ◽  
Y. Rostom ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Cancer Patients ◽  
Dose Response ◽  
Oropharyngeal Cancer ◽  
Dynamic Imaging ◽  
Swallowing Muscles ◽  
Kinetics Of

scholarly journals Comparison of regional lung perfusion response on longitudinal MAA SPECT/CT in lung cancer patients treated with and without functional tissue-avoidance radiation therapy

2019 ◽  
Vol 92 (1103) ◽  
pp. 20190174 ◽  
Author(s):  
Hannah Mary T Thomas ◽  
Jing Zeng ◽  
Howard J Lee, Jr ◽  
Balu Krishna Sasidharan ◽  
Paul E Kinahan ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Radiation Therapy ◽  
Cancer Patients ◽  
Dose Response ◽  
Lung Perfusion ◽  
Ct Scans ◽  
Lung Dose ◽  
Lung Cancer Patients ◽  
Response Slope ◽  
Regional Lung

Objective: The effect of functional lung avoidance planning on radiation dose-dependent changes in regional lung perfusion is unknown. We characterized dose-perfusion response on longitudinal perfusion single photon emission computed tomography (SPECT)/CT in two cohorts of lung cancer patients treated with and without functional lung avoidance techniques. Methods: The study included 28 primary lung cancer patients: 20 from interventional (NCT02773238) (FLARE-RT) and eight from observational (NCT01982123) (LUNG-RT) clinical trials. FLARE-RT treatment plans included perfused lung dose constraints while LUNG-RT plans adhered to clinical standards. Pre- and 3 month post-treatment macro-aggregated albumin (MAA) SPECT/CT scans were rigidly co-registered to planning four-dimensional CT scans. Tumour-subtracted lung dose was converted to EQD2 and sorted into 5 Gy bins. Mean dose and percent change between pre/post-RT MAA-SPECT uptake (%ΔPERF), normalized to total tumour-subtracted lung uptake, were calculated in each binned dose region. Perfusion frequency histograms of pre/post-RT MAA-SPECT were analyzed. Dose–response data were parameterized by sigmoid logistic functions to estimate maximum perfusion increase (%ΔPERFmaxincrease), maximum perfusion decrease (%ΔPERFmaxdecrease), dose midpoint (Dmid), and dose-response slope (k). Results: Differences in MAA perfusion frequency distribution shape between time points were observed in 11/20 (55%) FLARE-RT and 2/8 (25%) LUNG-RT patients (p < 0.05). FLARE-RT dose response was characterized by >10% perfusion increase in the 0–5 Gy dose bin for 8/20 patients (%ΔPERFmaxincrease = 10–40%), which was not observed in any LUNG-RT patients (p = 0.03). The dose midpoint Dmid at which relative perfusion declined by 50% trended higher in FLARE-RT compared to LUNG-RT cohorts (35 GyEQD2 vs 21 GyEQD2, p = 0.09), while the dose-response slope k was similar between FLARE-RT and LUNG-RT cohorts (3.1–3.2, p = 0.86). Conclusion: Functional lung avoidance planning may promote increased post-treatment perfusion in low dose regions for select patients, though inter-patient variability remains high in unbalanced cohorts. These preliminary findings form testable hypotheses that warrant subsequent validation in larger cohorts within randomized or case-matched control investigations. Advances in knowledge: This novel preliminary study reports differences in dose-response relationships between patients receiving functional lung avoidance radiation therapy (FLARE-RT) and those receiving conventionally planned radiation therapy (LUNG-RT). Following further validation and testing of these effects in larger patient populations, individualized estimation of regional lung perfusion dose-response may help refine future risk-adaptive strategies to minimize lung function deficits and toxicity incidence.

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