الفهرس 
Dosimetric evaluation of patient setup errors due to uncertainties during IMRT
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Abstract
This study aims to reduce the set error during IMRT and reduce
dose for healthy tissues and critical organs surrounding the tumor by
using on line image guided technique.
Intensity-modulated radiation therapy (IMRT) becomes
popular because dose escalation to the target can be done while
sparing adjacent normal tissues. IMRT tends to produce steep
absorb dose gradients between the target volume and the OAR. This
study was done to determine the error during RT on positioning
displacement for patients treated for H&N cancer and prostate cancer.
We tried to find the magnitude of daily setup errors to determine the
set up error cases. The results can help physicians to determine the
most suitable margin for H&N cases and prostate cases.
Data from 40 patients (20 patient for H&N cases and 20 patient
for prostate patient) calculated the Right/Left direction as X
direction, Anterior/ Posterior direction as Y shift and Up/Down
direction as Z shift. Average shift for all fractions calculated to be 0
.05 cm, 0.08 cm and - 0.02 cm as Rt/Lt, Ant./Post. And Up/Down
shifts for head and neck (H&N) patients and Average shift for all
fractions calculated to be 0.05 cm, -0.02cm and -0.39 cm as Rt/Lt,
Ant./Post. And Up/Down shifts for prostate patients.
To reduce setup errors in patients with H&N and prostate
cancer receiving RT, the use of on-line image-guided radiotherapy
is recommended to increase accuracy.