976 / 1096
S960
ESTRO 36
_______________________________________________________________________________________________
1
La Fe University and Polytechnic hospital, Radiotherapy,
Valencia, Spain
2
Clínica Benidorm, Radiotherapy, Benidorm, Spain
3
General University hospital, Radiation Oncology,
Valencia, Spain
4
General University hospital, Medical Physics, Valencia,
Spain
5
University of Valencia, Physiology, Valencia, Spain
Purpose or Objective
A risk analysis of the Total Skin Electron Irradiation (TSEI)
technique was performed. The aim of this study was to
evaluate the safety and the quality of the treatment
process, as well as to adapt the quality assurance program
according to the results.
Material and Methods
This revision has been executed in a reference center in
the TSEI technique, with 80 patients treated following the
method Stanford. The risk analysis was made following the
methodology proposed by the TG-100 of the AAPM, which
is an alternative procedure to the guidelines proposed by
the ESTRO in the ACCIDRAD project. To this end, a
multidisciplinary team developed the process map,
outlining the stages of treatment and steps in which each
stage is divided. The potential failure modes (FMs) of each
step were proposed and evaluated, according their
severity (S), occurrence (O) and detectability (D), with a
scale from 1 to 10. The product of this factors resulted in
its priority number risk (RPN), which enabled ranking the
FMs. Then, the current quality management tools were
examined and the FMs were reevaluated taking to account
these tools. Finally, the FMs with RPN ≥ 80 were studied
and new quality management tools to reduce its RPN were
proposed.
Results
75 steps contained in a total of 12 stages were observed.
361 FMs were evaluated, initially 103 had a RPN ≥ 80 and
41 had S ≥ 8. After, current management tools were
considered, only 30 FMs had RPN ≥ 80 (Figure 1). Thereby,
new control tools were derived from the study of these 30
FMs. The riskiest FMs were associated to the patient's
position during treatment. For the "general body
treatment" stage, the position of the screen and the
patient was marked on the floor (Figure 2a) and some
templates representing the position of the feet were
drawn (Figure 2b). In addition, to facilitate positioning of
the patient's limbs during “hands treatment” and “feet
treatment” stages, the axes must traverse the lasers and
the field size within which should position the extremities
were marked on the sheet (Figure 2c). These new
management tools have begun to be implemented in the
facility.
Conclusion
Thanks to this analysis, the steps of increased risk have
been discovered and new quality management tools have
been proposed. However, the multidisciplinary team will
perform this analysis periodically to increase the safety
and quality of TSEI treatment.
EP-1745 EPID and Gantry sag characterization in
Elekta LINAC
F. Tato de las Cuevas
1
, J. Yuste Lopez
1
1
Hosp. Univ. de Canarias, Medical Physics Dept., Santa
Cruz de Tenerife, Spain
Purpose or Objective
The EPID (Electronic Portal Imaging Device) is a well-
known useful tool for LINAC QA (like MLC QA). The position
of the EPID radiation center (
RC
) is crucial for this kind of
tasks. The purpose of this study is analyse the mechanical
performance of EPID and Gantry for LINAC QA with EPID.
Material and Methods
The LINAC used is an Elekta Synergy equipped with Agility
MLC and iViewGT EPID and 6 MV photons energy.