Treatment plan preparation and verification for total body irradiation using tomotherapy
PO-1361
Abstract
Treatment plan preparation and verification for total body irradiation using tomotherapy
Authors: Konstanty|, Ewelina(1)*[ewelina.konstanty@wco.pl];Malicki|, Julian(1);Skrzypczak|, Kaja(2);
(1)Greater Poland Cancer Centre, Department of Medical Physics, Poznan, Poland;(2)SPZOZ, Diagnostics Department, Slupca, Poland;
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Purpose or Objective
The purpose of the study was to develop a total body irradiation method on a tomotherapy accelerator (TTBI). Furthermore, the specific tasks include determining the selection of optimization parameters (Jaws, Pitch and MF) for whole body irradiation (TTBI) methods using CT images of the anthropomorphic phantom and also dosimetric verification of selected treatment plans on tomotherapy machine.
Material and Methods
TTBI plans for the Alderson phantom were created using various optimization parameters (Pitch, Jaws, MF). The prescribed dose for whole body was 12 Gy in 6 fractions, while limitation the dose in the lungs to 9 Gy. The most appropriate in terms of dose distribution and irradiation time plans were selected to pre-treatment verification and validation on patient''s CT images. TTBI phantom plans verified on a tomotherapy unit using the SunNuclear ArcCHECK device and analyzed with 3 mm shift, a 3% difference in dose for a minimum of 95% compatible points. Evaluation of the TTBI method on CT images of a treated with classic TBI method patient and an anthropomorphic phantom was done to introduce the method into clinical practice.
Results
The calculated dose distribution values for individual TTBI treatment plans met the set criteria. The plan with optimization parameters equal: Jaws - 5.0, Pitch - 0.287, MF - 2.5 or 3.0 proved to be the best plans (dose distribution and irradiation time). The average dose was 12.10 Gy, in lung volume 8.06 Gy, in bones 12.03 Gy. Created TTBI treatment plans for Alderson phantom and for patients had the same optimization parameters as the selected plans. Dosimetric verification of the TTBI treatment plan for the phantom was successful, results showed the correctness of the TTBI plans and the possibility of using them in clinical practice. The conducted research proved that the developed TTBI method equally fulfills the assumptions of the TBI and TMI method using tomotherapy machine. In the TTBI method, the whole body receives the planned dose of 12 Gy (as in TBI method using linear accelerator) and the same dose is administered to the bone (as in Total Marrow Irradiation).
Conclusion
The dose distributions received for the calculated TTBI treatment plans met all the criteria to implement thet in clinical practice. These method equally allowed obtaining a homogeneous dose in the target area (whole body) while limiting the average dose for lungs to 9 Gy.
Dosimetric verification enabled the acceptance of planned dose distributions and qualified the method for implementation on a tomotherapy machine.
Based on the received dose distributions of TTBI treatment plans for the phantom and patients'' CT images, the desirability of the TTBI method was proved. Thus, qualifying it for implementation in clinical practice.