الفهرس 
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Abstract
from the data obtained in this study, the following can be concluded:
In general, with respect to the planning target volume, the dose distribution
within the target volume, described by the three planning techniques; IMRT, ESSD, and 4-
fields obey the recommendations required by the Radiation Treatment Oncology Group
(RTOG), so, the three techniques can be used in the craniospinal irradiation (CSI).
But, with more precise comparison, the IMRT planning technique records more
advantages over the two other techniques (ESSD, and four-fields), as could be observed
throughout this work, i.e., the IMRT achieved the best Global max values rather than
those achieved by the ESSD, or four-fields as it was ≤ 107%.
Also, the IMRT planning technique results in more sparing the OARs, as it
delivers significant lower doses to these organs in comparison with those given by the
other two techniques.
However, the IMRT planning technique suffers more costs, as it needs specific
separate license for the Inverse Plan option for the TPS, also, needs another separate
license for the used machine, in addition to the medical physist must be of high level of
experience, which may be not satisfied with all the radiation therapy centers.
5.2 RECOMMENDATIONS
In case of applying craniospinal irradiation technique in the treatment of the common
malignant neoplasm of the central nervous system in children, such as, Medulloblastoma,
the three techniques IMRT, ESSD, and four-fields, can be used, but the priority of
application depends on the facilities of the radiotherapy center, and the condition of the
patient.
Chapter (5) Conclusion, Recommendation and Summary
94
5.3 SUMMARY
Of all the brain tumors, medulloblastoma represents approximately 20% of all
primary Central Nervous System tumors among children less than 19 years of age with
peak incidence between 5 to 9 years and most commonly seen in pediatric male.
Medulloblastoma occurs in cerebellum, a portion of the brain that plays vital role in
coordinating muscular movements. Medulloblastoma, and other brain tumors may tend to
spread, to other parts, via Cerebrospinal Fluid (CSF). The cause of medulloblastoma, in
most cases, is not known. In some cases, medulloblastoma is associated with certain
genetic , or inherited diseases, butit’s important to understand that these and other brain
tumors most often occur with no known cause. Accordingly, there’s nothing to do or to
avoid or preventing the tumor from developing. The treatment of medulloblastoma and
other brain tumors is accomplished using radiation therapy technique, known as
Craniospinal Irradiation (CSI).
The aim of the present study is to compare the radiation doses received by the
treatment of the target and organs at risk by using, three modalities used actually in
radiation therapy, namely; Intensity Modulated Radiation Therapy (IMRT), Extended
Source – Skin Distance (ESSD), and four-fields techniques in craniospinal cancer patients
treatment.
The thesis is divided into six chapters, summarized as follows:
Chapter one: (INTRODUCTION), it concerns with notes about definition and
categories of tumours, cancer incidence worldwide, types and units of ionizing
radiation, x-ray production, photons interaction, types and process of radiotherapy
and techniques used for treatment tumors in clinical medicine and brief note on the
incidence of craniospinal cancer. The end of the chapter concerns with a literature
review, and the aim of this study.
Chapter two: (SUBJECTS, AND METHODS). The chapter includes the patients
and methods used in this work. Fifteen patients of craniospinal cancer patients were
enrolled in the study. Three treatment planning techniques were performed,
Chapter (5) Conclusion, Recommendation and Summary
95
namely; intensity modulated radiation therapy, extended source – skin distance and
four-fields techniques.
- The planning target volume (PTV) and the volumes of the organs at risk were
delineated using CT scan (Siemens Somatom Computed Tomography Scanner) for
each patient, with a 1357.99cc ± 173.69cc .
- The CT data was imported to the contouring workstation via local area network
system.
- A software application medical system (CMS XiO version 4.64treatment planning
system) was used for the treatment planning procedures.
- For comparison, the estimation based on two evaluations; the qualitative
evaluation, and the quantitative evaluation. The qualitative evaluation, is important
to know the location of the hot and cold areas in the treatment plans, the
quantitative evaluations were extracted from the dose volume histograms (DVHs)
included; the mean dose (Dmean), the maximum dose (Dmax), the doses delivered to:
2% (D2), 5% (D5), 50% (D50), 95%(D95), and 98%(D98) of the PTV. Similarly, the
volumes covered by: 90% (V90), 95% (V95), and 107% (V107) of the prescribed
dose, homogeneity index (HI), conformity index (CI), global max (Gmax) were also
used in the comparisons.
- For OAR (the heart, both lungs, right kidney, left kidney, and liver), the doses
Dmean, Dmax and Dminwere evaluated for the comparisons.
Chapter three: (RESULTS). The results obtained throughout the study, can be
summarized, as follows:
- Significant difference, at the level of p ≤ 0.001, was observed between the
three planning techniques in case of; the mean dose(Dmean), maximum dose
(Dmax), D2, D5, D50, V107, in addition to the Conformity Index (CI), and Global
Max (Gmax), which indicate good distribution of the prescribed dose in the
planning target volume, with better results, in most cases, with the IMRT
planning technique, and significant difference between IMRT , and the other
two techniques, with no difference between ESSD, and 4-fields in most cases.
Chapter (5) Conclusion, Recommendation and Summary
96
Organs at Risk:
The heart, both lungs, both kidneys, and the liver, received minimum
mean doses, i.e., Dmean, Dmax, in case of the IMRT planning technique. However,
it must be noted that, no dose delivered to any organ at risk using any of the
three techniques exceeded the reported dose by the RTOG, but the IMRT
planning technique is the best in sparing the organ at risk.
Chapter four: (DISCUSSION) The chapter concerns with the overall conclusion.
Chapter five:(CONCLUSION, RECOMMENDATION AND English
SUMMARY).(THE CONCLUSION )The overall conclusion is that either of the
described technique can be used in the treatment of medulloblastoma brain tumor,
but the priority is devoted towards the IMRT planning technique, which is the best
in sparing the organs at risk, as judged by the minimum values in case V107, more
dose coverage and distribution in the PTV, and sparing the organs at risk.
(RECOMMENDATION). It is highly recommended that, the three techniques
IMRT, ESSD, and 4-fields, can be used, but the priority of application depends on
the facilities of the radiotherapy center, and the condition of the patient.
Chapter six: (THE REFERENCES). The references used through the whole
work are listed in it.