SGRT for pre-positioning in SBRT lung treatments: accuracy and efficiency evaluation.
PO-1852
Abstract
SGRT for pre-positioning in SBRT lung treatments: accuracy and efficiency evaluation.
Authors: Francesca Cavallo1, Stefania Caponigro1, Debora Di Minico2, Giusy Danaro3, Luigi Maida3, Luca Capone4, Leonardo Nicolini4, Sara Antonia Allegretta1, Francesco Maria Aquilanti3, Piercarlo Gentile4
1UPMC Italy, UPMC Hillman Cancer Center Villa Maria, Mirabella Eclano, Italy; 2UPMC ITALY, UPMC Hillman Cancer Center Villa Maria, Mirabella Eclano, Italy; 3Marrelli Hospital, Radiotherapy, Crotone, Italy; 4UPMC Italy, UPMC Hillman Cancer Center San Pietro, Roma, Italy
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Purpose or Objective
The recent introduction of SGRT (Surface Guided Radiation Therapy) in
clinical practice allows to check real time patient’s positioning using a
thermal camera, avoiding the use of ionizing radiations. The goal of our
multicentric study is to investigate the advantages in the use of SGRT systems
during the pre-positioning phase in SBRT lung treatments, comparing four different
set-up protocols in terms of efficiency and accuracy.
Material and Methods
SBRT Lung treatments represent a kind of procedure that requires great
accuracy in set-up with a longer lead time compared to others conventional
treatments due to the complexity of immobilization systems molding and setting.
Three highly specialized radiotherapy centers belonging to the same network, analyzed 4 different initial set-up protocols with different
immobilization systems in SBRT Lung treatments. A total number of 12 cases were
selected, 3 for each protocol. Among the protocols used for the set-up, two out
of four foresee the use of the SGRT as an initial experience for the real-time
correction of the patient's set-up in the pre-positioning phase:
- PROTOCOL
1: using SGRT
- PROTOCOL
2: using 3 points and automated shifts to isocenter
with SGRT real time check and corrections
- PROTOCOL
3: using 3 points and manual shifts to isocenter;
- PROTOCOL
4: using 3 points and automated shifts to isocenter.
To assess the advantages in using SGRT in the
patient's initial set-up, in terms of accuracy, data related to the corrections
applied with CBCT following the initial pre-positioning were collected and
analyzed. In terms of efficiency, positioning times were recorded for each of
the four protocols adopted in the centers, from patient access to bunker to the
start of CBCT acquisition.
Results
Shifts after SGRT setup and CBCT were 0.45 cm AP, 0.38 cm SI, 0.17 cm RL,
1.77 degrees PITCH, 0.57 degrees ROLL, 1.10 degrees YAW (average values for
Protocol 1); 0.27 cm AP, 0.32 cm SI, 0.44 cm RL, 1.54 degrees PITCH, 1.55
degrees ROLL, 1.28 degrees YAW (Average values for protocol 2). Shifts after pre-positioning without SGRT were 0.44 cm AP, 0.33 cm SI, 0.29
cm RL, 1.43 degrees PITCH, 1.13 degrees ROLL, 0.85 degrees YAW (average values
for Protocol 3); 0.44 cm AP, 0.27 cm SI, 0.40 cm RL, 1.10 degrees PITCH, 1.70 degrees
ROLL, 0.60 degrees YAW (average values for Protocol 4). The average of positioning time recorded for SGRT
set-up protocols were 2’14’’ for PROTOCOL 1, 3’ for PROTOCOL 2. The average of
positioning time recorded for no SGRT set-up protocols were 1’49’’ for PROTOCOL
3 and 4’30’’ for PROTOCOL 4.
Conclusion
No significant gains were found with the use of
the SGRT in terms of accuracy, as for each protocol CBCT detected shifts do not
exceed 0.5 cm for translational axis and 2 ° for rotational ones. Regarding efficiency,
the use of SGRT software has not still shown a real gain in terms of time saving
but reduces the possibility of occasional mistakes sending manual shifts from
the 3 points to the treatment isocenter.