ESTRO 2023 - Abstract Book

S1369

Digital Posters

ESTRO 2023

An automated treatment planning system has been clinically deployed in our institution for radiotherapy for various disease sites. ECHO saves resources and improved consistency of plan quality and enabled expedited treatment including same day SBRT treatment in our clinic.

Poster (Digital): Imaging acquisition and processing

PO-1667 Long axial field-of-view PET/CT-scanner for deep inspiration breath hold radiation therapy planning

L. Specht 1,2 , F.L. Andersen 3,4 , P.A. Andreasen 1 , D. Dejanovic 4 , A.K. Berthelsen 1 , J. Friborg 1,2 , M.G. Askløf 4 , P.M. Petersen 1 , E. Albrecht-Beste 4 , V.N. Hansen 1 , I.R. Vogelius 1,2 , B.M. Fischer 3,4 1 Rigshospitalet, Dept. of Oncology, Copenhagen, Denmark; 2 University of Copenhagen, Dept. of Health and Medical Sciences, Copenhagen, Denmark; 3 University of Copenhagen, Depth. of Health and Medical Sciences, Copenhagen, Denmark; 4 Rigshospitalet, Dept. of Clinical Physiology and Nuclear Medicine, Copenhagen, Denmark Purpose or Objective Objective: Modern, limited and highly conformal radiation therapy (RT) in deep inspiration breath hold (DIBH) has dramatically reduced toxicity for patients with mediastinal lymphomas. However, to enable optimal imaging with fusion of pre- and post-chemotherapy images for RT planning, the pre-chemotherapy staging PET/CT-scan must also be done in DIBH. Ideally, the entire PET-scan would be acquired in breath hold without fusion between sections, but this has not previously been possible. We report here for the first time the advantages of using a long axial field-of-view (LAFOV) PET/CT-scanner for whole body PET/CT-scans in DIBH specifically for treatment planning in DIBH. Materials and Methods Material & Methods: Patients with mediastinal lymphoma, who may need radiotherapy after their systemic treatment, have their initial staging (pre-chemotherapy) PET/CT performed in DIBH on a flat table-top and in a position suited for later RT. Until now this was performed on a conventional PET/CT-scanner with a field of view of 25 cm. In September 2021, a LAFOV PET/CT (Siemens Biograph Vision Quadra) was installed at our institution. The extended axial coverage (106 cm) and improved sensitivity prompted us to shift the pre-chemotherapy DIBH PET/CT-scans to the new scanner. Our standard procedure is now to perform a whole body DIBH diagnostic CT with i.v. contrast and 4 PET acquisitions in DIBH (each 18 seconds). Here we report on the first clinical experiences with this updated procedure. Results Results: The first three patients are presented. Implementation of DIBH on a LAFOV PET/CT scanner is feasible and well tolerated. DIBH PET/CT images of diagnostic clinical quality can be obtained in just 4 x 18 seconds. Clear advantages of the LAFOV DIBH PET/CT scans are: 2. Fusion of the pre-chemotherapy PET/CT-scan with the post-chemotherapy DIBH planning CT-scan is simpler and more precise, as the whole pre-chemotherapy scan is made in DIBH. This enables greater accuracy in the contouring of the target for RT 3. The i.v. contrast is visible in all parts of the pre-chemotherapy PET/CT-scan improving the diagnostic quality of the CT-scan, in particular regarding the PET-negative nodes often found in lymphomas 1. The pre-chemotherapy PET/CT-scan is simpler and faster.