Efficacy of FDG-PET for defining gross tumor volume of head and neck cancer.

We analyzed the data for 53 patients with histologically proven primary squamous cell carcinoma of the head and neck treated with radiotherapy between February 2006 and August 2009. All patients underwent contrast-enhanced (CE)-CT and (18)F-fluorodeoxyglucose (FDG)-PET before radiation therapy planning (RTP) to define the gross tumor volume (GTV). The PET-based GTV (PET-GTV) for RTP was defined using both CE-CT images and FDG-PET images.

[Investigation of vessel visibility in the iterative reconstruction method in coronary computed tomography angiography using simulated vessel phantom].

Iterative reconstruction methods can reduce the noise of computed tomography (CT) images, which are expected to contribute to the reduction of patient dose CT examinations. The purpose of this study was to investigate impact of an iterative reconstruction method (iDose(4), Philips Healthcare) on vessel visibility in coronary CT angiography (CTA) by using phantom studies. A simulated phantom was scanned by a CT system (iCT, Philips Healthcare), and the axial images were reconstructed by filtered back projection (FBP) and given a level of 1 to 7 (L1-L7) of the iterative reconstruction (IR).

Axillary lymph node accumulation on FDG-PET/CT after influenza vaccination.

Objective: 2-[(18)F]fluoro-2-deoxy-D: -glucose (FDG) is known to accumulate in benign conditions such as infection and inflammation as well as in malignancy. Vaccination may cause transient inflammation of lymph nodes, which may induce false-positive findings on FDG-positron emission tomography (PET) imaging. This study investigated the influence of influenza vaccination on FDG-PET/CT imaging in normal subjects.

[A study of collimator scatter factors of rectangular irradiation fields using the virtual source plane].

Kim introduced the geometric weighting factor concept into the field mapping method, and estimated collimator scatter factors of rectangular fields by correcting collimator exchange effects. The source plane is present at a specific position in the field mapping method, and, accordingly, the geometric weighting factor is constant. In this study, we changed the position of the source plane based on the measurement results, and we estimated the collimator factors of rectangular fields using the field mapping method.

[Application of PET in radiation oncology].

Positron emission tomography (PET), especially F-18 fluorodeoxyglucose (FDG)-PET, has been recently used to verify the target volume in radiation treatment planning (RTP) for malignancies. The utility of FDG-PET/CT in defining gross tumor volume (GTV) has been shown in many studies, and the target delineation by a fixed threshold of the maximum standardized uptake value (40-50%) is suggested to be useful in RTP for lung cancer, head and neck cancer, etc. But, the spatial resolution, sensitivity, and specificity of PET are not always enough to define the difference between the GTV and the clinical target volume(CTV).

Phantom study on radiotherapy planning using PET/CT--delineation of GTV by evaluating SUV.

We assessed the usefulness of PET/CT images to determine the target volume in radiotherapy planning by evaluating the standardized uptake value (SUV). We evaluated the imaging conditions and image-reconstruction conditions of PET/CT useful for treatment planning by collecting (18)F-FDG images of acrylic spheres (10-48 mm in diameter) in a phantom. The (18)F-FDG concentration in the spheres was 10-fold higher than that of the phantom.

Physical and histopathological assessment of the effects of metallic stents on radiation therapy.

To evaluate whether simultaneous metallic stent (MS) placement and radiotherapy are feasible, phantom and animal experiments were performed. The interface dose by external irradiation (EI) or intracavity irradiation (II) to 5 kinds of MS was measured using the charge-coupled device (CCD) camera with a thermoluminescent (TL) sheet, and backscatter and absorption were evaluated using composite method. Lineac 10 MV X-ray irradiated the MS in close contact with the TL sheet.