The Role of Myocardial SPECT in Evaluation of Irradiation-induced Changes.

* Inclusion Criteria: 1. Female patients with breast cancer who scheduled further regional RT. Groups of left-sided breast cancer (tomotherapy, conventional RT), and right breast cancer (conventional RT). 2. Aged 20-80 years old. * Exclusion Criteria 1. Pre-existing cardiac disease, such as prior myocardial infarction, documented CAD, congestive heart failure. 2. Pregnancy 3. Any medical contraindication of cardiac SPECT. * Estimated Case Number 20 female patients of each groups, respectively Group 1: Left-sided breast cancer, planning to received helical tomography Group 2: Left-sided breast cancer, planning to received local conventional RT Group 3: Right-sided breast cancer, planning to received local RT 1. Patients with breast cancer s/p operation will be transferred to CV OPD for initial cardiovascular risk factors assessment. 2. Past history, family history, basic lab data and Framingham cardiovascular risk assessment will be applied. Intermediated to high risk need further work-up, and undergo SPECT before further RT course. 3. All enrolled subjects provide basic demographic data and sign informed consents. 4. Myocardial perfusion images for baseline evaluation before RT. 5. The patients received scheduled treatment plan, including RT. 6. Follow-up CV OPD every 3 months. 7. Post-therapeutic myocardial perfusion study 12 months after first CV OPD visit. 8. Comparing the clinical follow-up data between groups, including global functional assessments, blood sampling data, myocardial perfusion scan, and quantitative cardiac functional parameters. Blood sampling Myocardial perfusion study- Patients referred for SPECT MPI for evaluation of CAD underwent a 1-day Tl-201 stress/rest MPI protocol, as daily practice in FEMH. Pharmacological stress was induced by standard dipyridomale infusion. Tl-201 of 2 mCi was injected after 7 min of induced stress. Each scan will be performed on an ultrafast CZT camera (Discovery 530 NMc, GE Healthcare). CZT images were reconstructed on the workstation using a dedicated iterative algorithm with maximum likelihood expectation maximization. Perfusion images in standard axis (short axis, vertical long axis, horizontal long axis) and polar maps of the left ventricle were obtained. Scans from CZT was analyzed in consensus by two experienced readers blinded to any information on patient identification. The software package with a 17-segment model for the left ventricle. Automated analysis of gated acquisitions from high-dose (rest) scans was performed to determine left ventricular ejection fraction. Integrated clinical information, follow-up and nuclear medicine cardiac scans performed in the time points of before \& after RT will be collected and analyzed.