Evaluation of IGRT-Induced Imaging Doses and Secondary Cancer Risk for SBRT Early Lung Cancer Patients In Silico Study.

OBJECTIVES: This study performed dosimetry studies and secondary cancer risk assessments on using electronic portal imaging device (EPID) and cone beam computed tomography (CBCT) as image guided tools for the early lung cancer patients treated with SBRT. METHODS: The imaging doses from MV-EPID and kV-CBCT of the Edge accelerator were retrospectively added to sixty-one SBRT treatment plans of early lung cancer patients. The MV-EPID imaging dose (6MV Photon beam) was calculated in Pinnacle TPS, and the kV-CBCT imaging dose was simulated and calculated by modeling of the kV energy beam in TPS using Pinnacle automatic modeling program. Three types of plans, namely PlanEPID, PlanCBCT and Planorigin, were generated with incorporating doses of EPID, CBCT and no imaging, respectively, for analysis. The effects of imaging doses on dose-volume-histogram (DVH) and plan quality were analyzed, and the excess absolute risk (EAR) of secondary cancer for ipsilateral lung was evaluated. RESULTS: The regions that received less than 50 cGy were significantly impacted by the imaging doses, while the isodose lines greater than 1000 cGy were barely changed. The DVH values of ipsilateral lung increased the most in PlanEPID, followed by PlanCBCT. Compared to Planorigin on the average, the estimated EAR of ipsilateral lung in PlanEPID increased by 3.43%, while the corresponding EAR increase in PlanCBCT was much smaller (about 0.4%). Considering only the contribution of the imaging dose, the EAR values for the ipsilateral lung due to the MV-EPID dose in 5 years,10 years and 15 years were 1.49 cases, 2.09 cases and 2.88 cases per 104PY respectively, and those due to the kV-CBCT dose were about 9 times lower, correspondingly. CONCLUSIONS: The imaging doses produced by MV-EPID and kV-CBCT had little effects on the target dose coverage. The secondary cancer risk caused by MV-EPID dose is more than 8.5 times that of kV-CBCT.

Individualized Fraction Regimen of SBRT Patients With Non-Small Cell Lung Cancer Based on Uncomplicated and Cancer-Free Control Probability.

INTRODUCTION: Stereotactic body radiotherapy (SBRT) currently adopts non-discriminative prescription regimen. This study attempts to investigate an individualized fraction regimen (IFR) method for SBRT patients with non-small cell lung cancer (NSCLC) based on Uncomplicated and Cancer-free Control Probability (UCFCP). METHODS: Twenty patients with NSCLC were retrospectively prescribed with 40 regimens, ranging from 8Gy×5f to 12Gy×5f in step of 0.1 Gy. Taking into consideration of the age and the BMI index of each patient as well, the tumor control probability (TCP), the normal tissue complication probability (NTCP) of the total lung, chest wall and rib, and the secondary cancer probability (SCP) of the total lung were calculated for each plan of the patients. For the 40 regimens, the UCFCP was calculated and the maximum value of UCFCP was the IFR of the specified patient. Besides, IFR of UCP approach which only took account of the TCP and NTCP was also derived and to be compared with the IFR based on the UCFCP method. RESULTS: For all the patients, the UCFCP value showed a bell-shaped trend with the change of prescription dose. Among the 20 patients, the IFRs of 16 patients were different from the original fixed regimen. Of the 16 patients, the IFR of 5 patients exhibited slight changes between UCP and UCFCP methods. CONCLUSION: The method based on the maximum value of UCFCP function may be helpful to provide IFR for specific SBRT patients with NSCLC, differentiating the patient specific characteristics such as anatomical structures and locations.

[Application of prospective ECG-triggering dual-source CT angiography in infants and children with congenital heart disease].

OBJECTIVE: To explore the application of prospective ECG-triggering dual-source CT (DSCT) angiography in infants and children with complex congenital heart disease (CHD) compared with transthoracic echocardiography (TTE). METHODS: Eighty-seven patients (mean age: 28 months, range 3 months to 6 years; male 46; mean weight: 15 kg) underwent prospective ECG-triggering DSCT angiography and TTE. Surgery was performed in 54 patients. The overall imaging quality was evaluated on a four-point scale. Inter-observer agreement in subjective image quality grading was assessed by kappa statistics. The accuracy of DSCT angiography and TTE was calculated based on the surgery findings in the 54 patients who were performed with surgery. RESULTS: A total of 267 cardiovascular deformities were diagnosed by DSCT angiography, and 231 deformities were diagnosed by TTE. There was a good agreement on overall image quality (kappa = 0.78). A total of 173 cardiovascular deformities were confirmed by surgery findings in 54 patients. The accuracy of DSCT angiography and TTE was 97.69% (169/173) and 82.08% (142/173). The mean effective dose was (0.40 ± 0.08) mSv. CONCLUSIONS: Prospective ECG-triggering DSCT angiography with a very low effective radiation dose allows the accurate diagnosis of anomalies in infants and children with complex CHD compared with TTE. It has great value for preoperative assessment of CHD.

Significance of the preoperative guidance of dual-source CT in carotid body tumor.

BACKGROUND: Accurate views of the head and neck vessels, tumor angiogenesis and the relationship of tumor and the surrounding blood vessels are especially crucial to carotid body tumor (CBT) patients. The aim of this study was to explore the value of dual-source CT (DSCT) cerebral and carotid angiography in CBT diagnosis. METHODS: DSCT cerebral and carotid angiography was performed on nine patients with CBT. Two-dimensional and three-dimensional reconstruction images were obtained by means of multiple planar reconstructions (MPR), maximum intensity projection (MIP) and volume rendering (VR). All patients were subjected to color Doppler flow imaging (CDFI) examination. Two kinds of examinations were performed in 3 days, and all patients were confirmed by surgery. RESULTS: DSCT angiography was successful in all patients. CBTs were diagnosed in 9 patients with 10 lesions (1 case had multiple bilateral CBTs). The largest lesion was 12 cm in diameter, and the smallest one was 1.6 cm in diameter. All patients had clearly demonstrated head and neck vessels, tumor angiogenesis, and tumor relationship with the surrounding blood vessels. The internal and external carotid artery (ICA, ECA) were involved in 2 cases. There were 7 cases with basilar artery ring integrity, and 1 case had the posterior communicating artery absent; 1 case had middle cerebral artery stenosis; 4 cases (4 tumors) showed arterial phase homogeneous enhancement; 5 cases (6 tumors) had obvious heterogeneous enhancement where irregular low-density necrosis could be seen in the tumors. CDFI could demonstrate the nearby blood vessels and tumor structure, instead of tumor angiogenesis. However, DSCT can display both the tumor and the peripheral vascular tumor angiogenesis consistent with surgical findings. CONCLUSIONS: DSCT cerebral and carotid angiography can provide reliable information for the operation. It might be a valuable CBT diagnostic method by showing accurate views of the CBT along with the bilateral neck and brain blood vessels.

Diagnostic value of dual-source CT in Kawasaki disease.

BACKGROUND: Doppler color echocardiography is a common method for detecting coronary artery lesions in patients with Kawasaki disease (KD). However, the diagnostic accuracy for the whole coronary artery lesions is limited. The purpose of this study was to compare the diagnostic value of dual-source computed tomography (DSCT) and Doppler color echocardiography for the assessment of coronary artery lesions caused by KD. METHODS: Sixteen patients, 12 with typical KD and 4 with atypical KD, underwent DSCT and Doppler color echocardiography. The position and internal diameter of each coronary artery lesion was measured. Correlation analysis was used to compare the diagnostic value of the two imaging modalities. RESULTS: In the typical KD group, seven patients did not have any coronary artery lesion as confirmed by both DSCT scans and Doppler color echocardiography; in four patients proximal coronary artery injuries were identified by both modalities; in one patient an aneurysm in the middle and distal segments of the coronary artery was detected by DSCT but was negative in Doppler color echocardiography. In the atypical KD group, three cases showed the same results with both modalities, while one case with coronary artery stenosis in the middle segment was identified by DSCT but not detected by Doppler color echocardiography. There was a good correlation between the two imaging modalities (Kappa value, 0.768 (>or= 0.75)). CONCLUSION: DSCT coronary artery angiography is an accurate, non-invasive, and valuable technique for detecting and following up coronary artery lesions in patients with KD.