Establishment of the Commissioning Procedure for Modifying the Beam Model of Helical Tomotherapy.

Although much evidence about the helical tomotherapy system are available, there is not a document about the procedure of quality assurance (QA) for changing the beam model. This study establishes the commissioning procedure for modifying the beam model of helical tomotherapy. Firstly, some intensity-modulated radiotherapy (IMRT) plans were created, and compared them with the calculated dose and the measured dose. Secondly, the absorbed doses to water in the machine-specific reference field and the plan-class specific reference field with a protocol in Japan; Standard Dosimetry of Absorbed Dose to Water in External Beam Radiotherapy (Standard Dosimetry 12) were measured. Thirdly, we reconfirmed patient-specific quality assurance. The recommended commissioning procedure after the change of the beam model was shown through three verification processes. This report would be helpful for not only changing the beam model of helical tomotherapy but also introducing Standard Dosimetry 12 to a clinic.

A 18F-labeled BF-227 derivative as a potential radioligand for imaging dense amyloid plaques by positron emission tomography.

PURPOSE: The aims of this study were to evaluate the binding and pharmacokinetics of novel 18F-labeled ethenyl-benzoxazole derivatives (i.e., [18F] fluorinated amyloid imaging compound of Tohoku university ([18F]FACT)) as amyloid positron emission tomography (PET) tracers and to assess [18F]FACT efficacy in imaging of Alzheimer's disease (AD). PROCEDURES: Binding assay was conducted using synthetic amyloid-ß (Aß) fibrils, fluorescence microscopy, and autoradiogram in three postmortem AD brains. Pharmacokinetics of [18F]FACT was assessed using 12 Crj:CD-1 (ICR) mice. In vivo binding ability with brain amyloid was investigated using amyloid precursor protein (APP) transgenic mouse. Clinical PET scanning using [18F]FACT was performed in ten healthy controls and ten mild cognitive impairment and ten AD patients. RESULTS: [18F]FACT showed high binding affinity for synthetic Aß fibrils, preferential binding to dense cored plaques in brain sections, and excellent brain uptake and rapid clearance in mice. Injection in APP mice resulted in specific in vivo labeling of amyloid deposits in the brain. PET scans of AD patients showed significantly higher [18F]FACT uptake in the neocortex compared to controls (P<0.05, Kruskal-Wallis test). CONCLUSION: [18F]FACT is a promising agent for imaging dense Aß plaques in AD.

Voxel-based analysis of amyloid positron emission tomography probe [C]BF-227 uptake in mild cognitive impairment and alzheimer's disease.

AIM: To determine early brain changes in the distribution of an amyloid positron emission tomography (PET) probe, (11)C-labeled BF-227 or [(11)C]BF-227, in order to accurately predict the progression of mild cognitive impairment (MCI) to Alzheimer's disease (AD). PATIENTS AND METHODS: Amyloid plaque burden was evaluated using [(11)C]BF-227 PET in AD, MCI and aged normal controls. A voxel-based analysis of [(11)C]BF-227 PET images was performed to characterize the culprit brain lesion in patients with MCI who were destined to progress to AD, referred to as MCI converters (MCI-C). In addition, binding characteristics of BF-227 to amyloid deposits were examined using postmortem AD brain samples. RESULTS: Voxel-based statistical analyses of the BF-227 PET images clearly demonstrated an abnormal distribution of BF-227 mainly in the posterior association area in MCI-C and patients with AD. BF-227 uptake in the lateral temporal cortex was consistently observed in almost all MCI-C and patients with AD, and it distinguished MCI-C from MCI nonconverters. BF-227 binding strongly correlated with dense amyloid-ß protein plaque density, but not with diffuse plaque density in the frontal cortex. CONCLUSION: BF-227 uptake in the lateral temporal cortex is a reliable indicator that can be used for predicting prognosis in patients with MCI.