الفهرس 
TitleOnly 14 pages are availabe for public view
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Abstract
The greatest challenge for radiation therapy is to attain the highest probability of cure with the least morbidity. The simplest way in theory to increase this therapeutic ratio with radiation is to encompass all cancer cells with sufficient doses of radiation during each fraction, while simultaneously sparing surrounding normal tissues.
The radiotherapy techniques in the treatment of breast cancer vary in different institutions, but, in general, the issue of radiation dose delivery to the chest wall after total mastectomy or to the breast following breast conservation surgery remains complex.
This study includes twenty-five female patients with left breast cancer. For each patient wedged and non-wedged Field-In-Field radiotherapy treatment planning techniques were carried out to achieve an optimum plan for specific target and organ at risk. These techniques were designed using 3DCRT treatment planning system, at Ayadi Al-Mostakbal Oncology Center.
The results of the current study showed that, for the treatment target (PTV), the median doses received by PTV of left breast cancer in case of WFIF plan versus NWFIF plan. The values of D2%, D5%, and D50% were significantly lower in WFIF plan than in NWFIF plan but, the median doses received by PTV D95% and D98% were significantly higher in WFIF plan than in NWFIF plan. The median doses received by PTV D2%, D5%, and D50% were more than 100% of the total radiation dose. So, the bitter planning technique should decrease the over dose (more than 100% of the total prescribed dose) to the PTV. Also, the median doses received by PTV D95% and D98% were less than 100% of the total prescribed dose.
In the present study, the Volumes % of PTV covered with 70%, 90% and 95% (V70%, V90% and V95% consequently) of the total prescribed dose in WFIF technique were nearest to the acceptable ranges than in NWFIF technique. The Volume % of PTV covered with 107% (V107%) was greater in NWFIF technique than WFIF technique.
The better plan should achieve better and homogeneous dose distribution to the PTV. The minimum and maximum acceptable radiation doses to the PTV should be (95% - 107%)which is achieved by the WFIF. Thus, we can demonstrate that the dose coverage to the PTV was better in WFIF plan than NWFIF plan.
For Organs at Risk, with respect to dosimetric parameters for organs at risk, the comparison of WFIF plan with NWFIF plan showed that, the median doses delivered to ipsilateral lungs, heart, contralateral breast and contralateral lung irradiated with WFIF-plan were higher than that for NWFIF plan. but those doses were still within the dose tolerance of the Lt Breast Cancer Organs at Risk.
Thus, we can demonstrate that; The main aim of radiotherapy planning techniques is to achieve a good dose coverage to the treatment target and at the same time spare the organs at risk (which are near or closed to the treatment target) from irradiation to radiation doses more than the maximum acceptable values for them which can be considered a
Summary and Conclusion
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complex equation. The better technique should achieve that complex equation. Despite of being the OARs received higher doses in WFIF than in NWFIF, but they were within dose tolerance for every organ and also WFIF achieved better dose coverage to the treatment target than NWFIF.