[Use of multimodality imagery in radiotherapy]

Area of Science:

• Medical Physics
• Radiotherapy
• Diagnostic Imaging

Background:

• Conformal radiotherapy requires precise delineation of organs at risk and gross tumor volume (GTV).
• Accurate treatment planning necessitates 3D imaging, combining anatomical and functional data.
• Current limitations in visualizing tumors and differentiating post-treatment changes necessitate advanced imaging techniques.

Purpose of the Study:

• To highlight the importance of 3D imaging in conformal radiotherapy.
• To discuss the integration of various imaging modalities for precise treatment planning.
• To address the challenges and advancements in image registration for radiotherapy.

Main Methods:

• Utilizing computed tomography (CT) for electronic density and dose calculation.
• Employing magnetic resonance imaging (MRI) for superior visualization of tumors and anatomical structures.
• Integrating positron emission tomography (PET) or single-photon emission computed tomography (SPECT) for functional and metabolic assessment.
• Performing image registration between different modalities, with patient in treatment position.
• Exploring the use of hybrid imaging systems (CT-PET, CT-SPECT) for simultaneous data acquisition.

Main Results:

• CT provides essential electronic density data for accurate dose calculations.
• MRI enhances visualization of tumors and soft tissues, compensating for CT's limitations.
• PET/SPECT imaging identifies metabolically active tumor regions, crucial for distinguishing recurrence or fibrosis.
• Image registration is vital for accurately localizing functional abnormalities within anatomical context.
• Simultaneous imaging on hybrid systems simplifies the registration process and improves patient positioning accuracy.

Conclusions:

• Precise conformal radiotherapy necessitates accurate 3D delineation of target volumes and organs at risk.
• Multi-modal imaging, including CT, MRI, and PET/SPECT, is crucial for comprehensive treatment planning.
• Image registration techniques are essential for integrating data from different modalities.
• Advancements like hybrid imaging systems offer improved accuracy and efficiency in radiotherapy planning.