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P2.05 - Interventional Diagnostic/Pulmonology (ID 168)
- Event: WCLC 2019
- Type: Poster Viewing in the Exhibit Hall
- Track: Interventional Diagnostics/Pulmonology
- Presentations: 1
- Now Available
- Coordinates: 9/09/2019, 10:15 - 18:15, Exhibit Hall
P2.05-06 - New Dosimetric Parameters Encompassing High Attenuation Enables More Accurate Prediction of Radiation Pneumonitis in Various Types of Cancers (Now Available) (ID 66)
10:15 - 18:15 | Author(s): Takuya Tsugawa
Radiation pneumonits (RP) is an important side effect of radiotherapy, especially symptomatic pneumonitis interferes chemotherapy after radiotherapy. Therefore, prediction and prevention symptomatic radiation pneumonitis is very important. Even if only lung cancer patients, the reported threshold values of dosimetric volume histogram to predict radiation pneumonitis were ranging among studies . This caused the guidelines of thoracic radiation therapy set ambiguous cut-off values of conventional dosimetric parameters like Mean lung dose (MLD) (20−23Gy) and the percentage of lung volume receiving 20 Gy or more (V20%) (30%−40%) to reduce the risk of RP. We had previously shown that dosimetric parameters calculated using only high attenuation area by excluding emphysematous lesion were better predictors of RP than conventional parameters. Little is known about the threshould value of dosimetric parameters to predict RP among different types of cancers, and if the threshould were closer or same, it will be able to provide a more reliable and versatile . To evaluate if our new dosimetric parameters can predict RP more accurately without changing threshold values among different types of cancers, we compared the performance of our new dosimetric parameters with conventional parameters to predict RT in esophageal cancer patients and lung cancer patients.
We retrospectively evaluated 77 patients who received radiotherapy for lung cancer and 71 patients for esophageal cancer. RP was graded according to the Common Terminology Criteria for Adverse Events (version 5.0). We quantified high attenuation volume (HAV) using quantitative computed tomography analysis. We compared traditional dosimetric parameters and dosimetric parameters with HAV in both lung cancer and esophageal cancer patients. Finally, the threshold of dosimetric parameters predicted of symptomatic RP and the difference of the threshold of dosimetric parameters between lung cancer patients and esophageal cancer patients were compared.Result
The predictive performance of dosimetric parameters for symptomatic RP was compared using AUC. MLD, HAV30% (The percentage of lung with high attenuation volume receiving ≥ 30 Gy), and HAV20% were top three parameters in lung cancer and, HAV10%, HAV5%, and V10% were in esophageal cancer. Comparing difference of the threshold of parameters predicting RP between two cancers, HAV30% revealed same value in both two cancers. In any dosimetric parameters, dosimetric parameters with HAV have smaller difference of the threshold between both cancer patients than in cases of traditional dosimetric parameters.Conclusion
Dosimetric parameters with high attenuation area may have higher commonality than traditional dosimetric parameters in any populations.
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