Volumetric modulated arc therapy based Total Body Irradiation (TBI): a single center experience
PO-1169
Abstract
Volumetric modulated arc therapy based Total Body Irradiation (TBI): a single center experience
Authors: Filippo Mammini1,2, Ilario Ammendolia1, Elisa Deraco1,3, Letizia Cavallini4,5, Federica Medici3,4, Gianfranco Cicoria6, Silvia Strolin6, Giulia Paolani6, Miriam Santoro6, Lidia Strigari6, Alessio Giuseppe Morganti7,3, Silvia Cammelli7,3
1ircss Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, bologna, Italy; 2Alma Mater Studiorum University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-dimes, bologna, Italy; 3Alma Mater Studiorum University of Bologna, Diagnostic and Specialty Medicine-dimes, bologna, Italy; 4IRCSS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, bologna, Italy; 5Alma Mater Studiorum University of Bologna, Diagnostic and Specialty Medicine-dimes, Bologna, Italy; 6IRCCS Azienda Ospedaliero-Universitaria di Bologna, Medical Physics Unit, bologna, Italy; 7IRCCS Azienda Ospedaliero-Universitaria di Bologna, Radiation Oncology, bologna, Italy
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Purpose or Objective
Total body irradiation (TBI) can be part of the conditioning regimen for patients with leukemia undergoing hematopoietic stem cell transplantation.
Aim of this study is to describe the experience gained at our institute with a dedicated EPID-based couch coupled for delivering a volumetric modulated arc therapy (VMAT )-based TBI.
Material and Methods
Selected patients underwent a total body CT in prone and supine position two weeks before treatment. A vacuum positioning cushion was used for immobilization. An experienced radiation oncologist was responsible for delineating the treatment target (whole body) and organs at risk. To limit the mean lung dose below 10 Gy, customized lung shields were produced for each patient using a 3D printer.
Subsequently, a highly customized plan was calculated using Pinnacle TPS (Philips Radiation Oncology Systems, Fitchburg, WI). A dedicated couch with integrated EPID panels for performing online setup imaging and accurately positioning the printed lung blocks was used before delivering TBI, in supine and prone position. The prescribed dose was 12 Gy in twice daily fractionation (2 Gy per fraction), delivered by single modulated sweeping-arc technique.
Results
A total of 16 patients (median age: 33 years, range: 8 – 56) were treated at our Institute from April 2021 to April 2022. Conditioning chemotherapy before TBI was given to 11 out of 16 patients, in the remaining cases it was performed after radiation therapy.
The dedicate couch with integrated EPID panel allowed a reproducible patients and lung shields positioning in all cases.
The treatment was completed correctly by the totality of the proposed patients, and it was well tolerated overall. During three days of TBI treatment 2/16 patients developed parotitis G1, 6/16 patients developed nausea G1, 5/16 patients developed asthenia G1, G1 diarrhoea was described in a single case. All patients had leukopenia G2-3, mainly due to the previous chemotherapy conditioning regimen.
Hematopoietic stem cell transplantation was performed successfully for all patients. With a median follow-up of 7 months (range: 2 – 14), no cases of disease relapse have been reported.
Conclusion
The dedicated EPID-based couch VMAT TBI and the 3D-printed blocks proved to be a valid and feasible technique with well-manageable side effects that allowed us to achieve excellent reproducibility while keeping patient discomfort to a minimum. A prolonged follow-up will be needed for evaluation of late toxicities