J. Kriz1, C. Baues2, M. Oertel1, R. Engenhart-Cabillic3, K. Herfarth4, P. Lukas5, S. Marnitz-Schulze2, H. Schmidberger6, D. Vordermark7, U. Haverkamp1, A. Engert8, H. T. Eich1
1 Department of Radiation Oncology, University of Muenster, 2 Department of Radiation Oncology, University of Cologne, 3 Department of Radiation Oncology, University of Marburg, 4 Department of Radiation Oncology, University of Heidelberg, 5 Department of Radiation Oncology, University of Innsbruck, 6 Department of Radiation Oncology, University of Mainz, 7 Department of Radiation Oncology, University of Halle, 8 First Department of Internal Medicine, University of Cologne
Introduction: The quality assurance (QA) of radiotherapy (RT) within the German Hodgkin Study Group (GHSG) was established 20 years ago. The work was modified in the 6th study generation and adapted to the demands of „modern“ RT (IMRT, VMAT, IGRT). The Involved-Node radiotherapy (IN-RT) was implemented into the HD17-trial for the first time within the GHSG trials. Therefore QA plays an important role.
Methods: Patients within the HD17 trial (early unfavorable stages) recieved 2 cycles BEACOPPesc and 2 cycles ABVD followed by a PET scan. In the standard arm all patients received 30 Gy IF-RT independent of the result of the PET scan. In the experimental arm PET-positive patients were irradiated with 30 Gy IN-RT and patients with a negative PET scan were observed. The expert panel consisting of 6 experienced radiation oncologists and one medical physicist evaluated the adequacy of the IN-RT, technical and physical parameters. Further the diagnostic as well as the planning CT scans were analysed. As verification the Electronical Portal Imagings (EPI) and Cone Beam-CT (CBCT) were sent in. The assessment was done by using the following criteria: according to protocol, acceptable and not acceptable.
Results: A total of 1100 patients were treated in the HD17 trial from 2012–2017. 330 patients had a PET positive result after completion of chemotherapy. 419 patients recieved IF-RT and 148 IN-RT. This analysis comprises data of 55 patients (35%) treated with IN-RT. RT was assessed as according to protocol in 67% (n = 37), acceptable in 24% (n = 13) and not acceptable in 9% (n = 5). In comparison to these findings IF-RT was assessed as not acceptable in 52% in the 4th and 5th study generation.
Following techniques were used: APPA n = 12 (22%), 3D-CRT n = 24 (44%), IMRT n = 12 (20%), VMAT n = 5 (9%) and Tomotherapy n = 3 (9%).
Conclusion: The quality of RT was on a high level and showed an improvement compared to the former study generations. The process of QA is very elaborative due to the amount of analysed data. In the future the question will arise whether protocol violations have an impact on recurrences in the era of smaller target volumes.