COMPARISON OF DOSIMETRIC CONSTRAINTS BETWEEN CONFORMATIONAL RADIOTHERAPY AND INTENSITY MODULATED RADIOTHERAPY, ON ORGANS AT RISK IN TREATMENT OF BRAIN TUMORS

Ghammad Sanae*, Abboud Fatimazhrae, Allouche Fadwa, Terrab Fatimazahrae, Bouhafa Touria, Alami Zenab and Hassouni Khalid

ABSTRACT

Over the past two decades, radiation delivery has evolved from conventional external beam two-dimensional RT (2DRT) to three dimensional conformal RT (3DCRT). In a further advance, intensity-modulated RT (IMRT) uses computed tomography-based planning and delivery of radiation, aided by computerized optimization of the intensities of multiple beams. This improves the ability to tightly conform the treatment volume to concave tumor shapes, while minimizing doses to organs at risk (OAR), it can provide significantly better tumor target coverage and sparing of sensitive normal tissue compared with 3DCRT. Intensity-modulated radiation therapy (IMRT) using dynamic or static multileaf collimators delivers highly conformal dose while sparing the surrounding normal structures. Using a conventional multileaf collimator can be made in a “dynamic” or “static” form. The dosevolume- histogram (DVH) is a common tool to express the dose that is delivered to targets and organs-at risk (OAR). A DVH contains information about the doses delivered to partial volumes (either absolute or relative) of targets or OARs. However, DVHs do not provide spatial information such as the location of the high- and low-dose regions (“hot” and “cold” spots) inside the volume of interest (VOI). Our big interest of our study is to compare target dose distribution and dose to normal tissue for brain tumors using intensity modulated and three dimensional conformal radiotherapy.

Keywords: Intensity-modulated radiation therapy, three dimensional conformal radiotherapy, brain tumors, radiotherapy, comparison.