Background: Despite the benefits of contrast-enhanced computed tomography (CT) scans in better tumor volume delineation, it can affect accuracy dose calculation radiation therapy. This study examined this effect on a thorax phantom. Objectives: The influence different variables including concentrations Visipaque contrast media, sizes, and CT scan energies measurement was examined. Methods: Tran...

In order to model photon attenuation and detector resolution variation as a depth-dependent convolution for efficient reconstruction of quantitative SPECT, a central-ray approximation is necessary. This work investigates the impact of the approximation upon reconstruction accuracy and computational efficiency. A patient chest CT image was acquired and converted into an object-specific attenuati...

Positron Emission Tomography is an important functional imaging technique in nuclear medicine, where the measured data are corrupted by Poisson noise. Hence, this thesis begins with an overview on PET and the introduction of a mathematical and statistically motivated model in order to deal with the emerging inverse problem. At this point numerical methods like regularization are required for im...

Automatic exposure control (AEC) in computed tomography (CT) facilitates optimisation of dose absorbed by the patient. The use of AEC requires appropriate 'patient centring' within the gantry, since positioning the patient off-centre may affect both image quality and absorbed dose. The aim of this experimental study was to measure the variation in organ and abdominal surface dose during CT exam...

The goal of this study was to determine the quantitative accuracy of our OSEM-APDI reconstruction method based on SPECT/CT imaging for Tc-99m, In-111, I-123, and I-131 isotopes. Phantom studies were performed on a SPECT/low-dose multislice CT system (Infinia-Hawkeye-4 slice, GE Healthcare) using clinical acquisition protocols. Two radioactive sources were centrally and peripherally placed insid...

While most currently available minimally invasive robotically assisted cardiac surgical systems do not employ 3D image guidance, such support can be generated using pre operative images such as CT. Previously we demonstrated a virtual model of the thorax with simulated surgical instruments, and a pulsating virtual model of the coronary arteries. In this paper we report the overlay of optical en...

The purpose of this investigation was to evaluate the dose on megavoltage CT (MVCT) images required for tomotherapy. As imaging possibilities are often used before each treatment and usually used several times before the session, we tried to evaluate the dose delivered during the procedure. For each scanning mode (fine, normal, and coarse), we first established the relative variation of these d...