Low-dose whole-spine imaging using slot-scan digital radiography: a phantom study.

BACKGROUND: Slot-scan digital radiography (SSDR) is equipped with detachable scatter grids and a variable copper filter. In this study, this function was used to obtain parameters for low-dose imaging for whole-spine imaging. METHODS: With the scatter grid removed and the beam-hardening (BH) filters (0.0, 0.1, 0.2, or 0.3 mm) inserted, the tube voltage (80, 90, 100, 110, or 120 kV) and the exposure time were adjusted to 20 different parameters that produce equivalent image quality. Slot-scan radiographs of an acrylic phantom were acquired with the set parameters, and the optimal parameters (four types) for each filter were determined using the figure of merit. For the four types of parameters obtained in the previous section, SSDR was performed on whole-spine phantoms by varying the tube current, and the parameter with the lowest radiation dose was determined by visual evaluation. RESULTS: The parameters for each filter according to the FOM results were 90 kV, 400 mA, and 2.8 ms for 0.0 mm thickness; 100 kV, 400 mA, and 2.0 ms for 0.1 mm thickness; 100 kV, 400 mA, and 2.8 ms for 0.2 mm thickness; and 110 kV, 400 mA, and 2.2 ms for 0.3 mm thickness. Visual evaluation of the varying tube currents was performed using these four parameters when the BH filter thicknesses were 0.0, 0.1, 0.2, and 0.3 mm. The entrance surface dose was 59.44 µGy at 90 kV, 125 mA, and 2.8 ms; 57.39 µGy at 100 kV, 250 mA, and 2.0 ms; 46.89 µGy at 100 kV, 250 mA, and 2.8 ms; and 39.48 µGy at 110 kV, 250 mA, and 2.2 ms, indicating that the 0.3-mm BH filter was associated with the minimum dose. CONCLUSION: Whole-spine SSDR could reduce the dose by 79% while maintaining the image quality.

A retrospective observational study investigating the factors associated with right heart failure in patients with primary acute pulmonary embolism and deep vein thrombosis.

BACKGROUND: The relationship between the risk of right heart failure in primary acute pulmonary embolism after embolization and the residual thrombus sites in the pelvis and lower limbs is not clear. METHODS: This single-center retrospective observational study examined the results of contrast-enhanced computed tomography and venous ultrasonography of patients with primary acute PE and DVT. We assessed the association between the occurrence of right heart failure and age; gender; pulmonary thrombosis distribution; most proximal site of deep vein thrombosis in the soleal vein, inferior vena cava (IVC), or common iliac vein (CIV); DVT distribution; and malignancy using univariate and multivariate logistic regression. RESULTS: In all, 77 of 165 patients were male (mean age: 65.1 ± 13.7 years). Right heart failure occurred in 53 patients (32.1%). Multivariate analysis revealed that the odds ratio (OR) for right heart failure was significantly lower in patients with the most proximal site of DVT in the IVC/CIV (OR = 0.07, 95% confidence interval [CI] 0.01-0.62, P = .017), while it was significantly higher in females (OR = 2.51, 95% CI 1.05-6.01, P = .039), and in patients who exhibited the presence of bilateral venous thrombosis (OR = 3.89, 95% CI 1.60-9.48, P = .003). CONCLUSION: A significant factor involved in PE without right heart failure was the most proximal site of DVT in the IVC/CIV, and significant risk factors associated with PE with right heart failure were more prevalent in females and in patients who exhibited the presence of bilateral venous thrombosis.