Feasibility of Expediting Radiotherapy Clinical Workflow by Radiation Planning on Diagnostic Images

Abstract

Studies have showed that delays from diagnosis to radiotherapy (RT) are detrimental to outcome for many cancers. The purpose of this study is to assess the feasibility of expediting clinical workflow by combining planning on diagnostic images and adaptive RT in order to eliminate treatment delays associated with RT simulation imaging. A cohort of 30 lung patients previously treated with RT were included. CT images acquired for diagnostic purposes on curved couch without proper immobilization for RT were used for diagnostic plans (Dd,d), employing knowledge-based treatment planning. The diagnostic plans were copied and recalculated on corresponding simulation CT images (Dd,s), which were the actual primary treatment datasets immobilized properly on flat therapy couch, to evaluate the likelihood of applying Dd,d for treatment directly. The diagnostic plans were scaled if needed to match PTV coverage at 95% of volume (Dd,s). Final plans (Ds,s) were reoptimized on the simulation CT images to best match the diagnostic plans, mocking an adaptive RT process. Changes in DVH were reported with Dd,d as the baseline. EUD-based tumor control probability (TCP) and normal tissue complication probability (NTCP) were reported to assess the consistency of clinical outcomes in all four scenarios. Ds,s matched Dd,d well in DVHs in all cases by visual check, while Dd,s and Dd,s matched Dd,d reasonably well in 21 out 30 cases. Scaling factor from Dd,s to Dd,s was 1.05 ± 0.04. Mean D95 in PTV changed slightly by -0.22% ± 0.41% (-0.12 ±0.24 Gy) from Dd,d to Ds,s, where mean changes of -0.14 ± 2.57 Gy, -0.92 ± 2.86 Gy, 0.99% ± 2.22%, 0.87 ± 1.3 Gy were observed in maximum cord dose, mean esophagus dose, lung V20 and mean heart dose, respectively. Mean TCP in Dd,d was 65.1% for PTV and changed by-0.02% from Dd,d to Ds,s. Mean NTCP in Dd,d were 0.02%, 5.67%, 0.32%, and 0.08%, and changed by 0.00%, 0.33%, 0.30%, and -0.02% for cord necrosis, esophageal perforation, pneumonitis and pericarditis, respectively, from Dd,d to Ds,s. Our results demonstrated that it is likely possible to expedite the clinical work flow by omitting simulation. It is feasible to plan on diagnostic CT images, then adapt during the treatment or treat directly or with a scaled plan depending on the treatment intent. This is regardless of patient positioning, couch types and immobilization devices.Abstract 1140; Table 1PTV D95 (%)Cord Max (Gy)Esophagus Mean (Gy)Lung V20 (%)Heart Mean (Gy)DVHDd,d100.3±1.737.9±8.321.1±8.321.1±7.28.2±5.4Dd,s92.5±8.438.8±10.120.4±7.524.2±16.19.7±5.9D’d,s96.8±6.140.7±10.721.4±8.124.9±16.110.2±6.4Ds,s100.1±1.537.8±8.120.2±7.322.1±7.99.1±5.7TCP/ NTCPPTVCord NecrosisEsophageal PerforationPneumonitisPericarditisDd,d65.1%±7.8%0.02%±0.03%5.7%±10.8%0.3%±0.7%0.08%±0.23%Dd,s47.3%±23.3%0.06%±0.15%4.4&%±9.2%4.0%±17.9%0.06%±0.175D’d,s50.5%±23.6%0.21%±0.55%10.8%±16.6%4.3%±18.2%0.15%±0.40%Ds,s65.1%±7.8%0.02%±0.02%6.0%±12.0%0.6%±1.6%0.06%±0.19% Open table in a new tab