الفهرس 
INTRODUCTION AND AIM OF THEOnly 14 pages are availabe for public view
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Abstract
SUMMARY
In this thesis, we present an intensitymodulated
radiotherapy technique based on forward
planning dose calculation to provide a concave dose
distribution to head and neck sequence cell carcinoma by
means of wedged dynamic arcs therapy (W-DAT) with
improved protection of organs at risk.
Eight patients were treated using W-DAT.
The dose prescription is 70Gy and 54Gy, in 35 fractions,
to the sites of gross disease PTV1 and to site of
microscopic disease PTV2 respectively. The four halfdynamic
arcs fields had fit PTV1 while shielding brain
stem combined with two anterior-posterior conformal
fields had only fit PTV1 to adjust the dose homogeneity.
Another two anterior-posterior conformal fields were used
to fit the neck nodes PTV2 and shield spinal cord by
means of multi leaf collimators (MLCs). All eight fields
were half-beam blocked to the central axis so that at the
isoplane there was no divergence and consequently no
dose overlap.
Referring to radiation therapy oncology group
protocol 0615, 95% of the PTV1 was covered by more
than 95% (66.50 Gy) of the prescribed dose, with very
low dose inhomogeneity index of 0.0670 ± 0.0007. The
maximum dose to 1% of the planning organ at risk
volumes-brainstem didn’t exceed 56.10 ± 2.17 Gy while
the two parotids were well spared as they received a mean
dose of 21.97 ± 3.24 Gy. Isocentric ion chamber
measurements showed good agreement with the treatment
planning system calculated dose with the maximum
deviation of 2.4% while film measurements yielded lesser
than 4.2% of the pixels failed the acceptance gamma
criteria of (3 mm, 3%).
Based on our results the W-DAT technique
was approved in our department as the standard choice for
the radical treatment of head and neck sequence cell
carcinoma