| Summary: | 碩士 === 長庚大學 === 醫學影像暨放射科學系 === 101 === The main goal in the radiotherapy is to maximize the tumor control probability (TCP) and minimize the normal tissue complication probability (NTCP). To achieve the goal, it is essential to formulate a treatment plan of high quality in which the target and organs at risk (OAR) are delineated with accuracy. In some specific scenarios, contrast agent (CA) media may be used in the CT scan for contrast enhancement in radiotherapy planning. However, errors may occur in dose calculations if CA is not administrated in the treatment delivery.
This thesis contains three parts. In the first part, Conray 60 (Mallinckrodt, St. Louis, USA), a clinical contrast agent, is considered. A water phantom in which a target is loaded with Conray 60 media is created in the treatment planning system.
The study includes different Conray 60 concentrations, irradiation techniques, treatment energies, dose calculation algorithms and CT scanning energies. A clinical scenario of cervical cancer is used to study the effect of Conray 60 on dosimetry in the recent RapidArc treatment.
In recent years of preclinical research in small animals, gold nanoparticles (AuNP) are identified as an excellent CA for x-ray based imaging. Our work of the second part is to investigate a possible scenario that AuNP is used as a contrast material for assisting target delineation in radiotherapy planning. The impact of AuNP on dosimetry and comparisons with Conray 60 are studied with an analytical phantom and clinical case.
In the last part, we investigate further a potential scenario that AuNP is used as a targeted drug carrier in radiotherapy. In this radiotherapy treatment projection with AuNP, AuNP media and external beams are delivered to patients simultaneously. The prostate phantom of AAPM TG 119 is used to study the clearance effect of AuNP on dosimetry with treatment techniques of IMRT and RapidArc.
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