Clinical scanning protocols for respiratory motion
In clinical imaging,
there are three main methods considered from the viewpoint of reducing radiation exposure dose.
(fig.4 Clinical scanning protocols for respiratory motion)
1.
Continuous scan: 120 kV,
10 mA,
0.35 s,
1 mm x 160,
continuous scan,
one breath
2.
Intermittent scan: 120 kV,
10 - 40mA,
0.35 s,
1 mm x 160,
x 6 scans,
one breath
3.
Respiration-gated scan: depending on the number of scans
fig.5 dynamic movie of right lung cancer
Techniques of radiation dose reduction
1.
AIDR3D: Adaptive Iterative Dose Reduction Algorithm (fig.6)
AIDR 3D is a noise reduction technique in the raw data space and image data space.
Using the AIDR 3D technique can improve image quality in reduced- or low-dose CT scans on patients with pulmonary diseases.
Decrease radiation dose by 90-50%.
fig.7 ultra-low-dose CT using AIDR3D
2.
PhyZiodynamics: Increase image frames and noise reduction using voxel tracking algorithm (fig.8 fig.9)
The voxel-to-voxel mapping enables the employment of additional algorithms that reduce noise,
improve motion coherence,
and measure kinematic function.
fig.10 noise reduction effects using voxel tracking algorithm
fig.11 increase image frames using voxel tracking algorithm
fig.12 repiratory movement usuing original CT data (6 frames)
fig.13 repiratory movement usuing voxel tracking algorithm (30 frames)
Clinical cases
fig.14 Ground-grass type Adenocarcinoma
fig.15 Solid type Squamous cell carcinoma
fig.16 Emphysema: parenchymal movement and air trapping are clearly depicted.
fig.17 Chest wall adhesion of lung cancer
fig.18 Velocity map of the lung: Velocity of local lung parenchyma can be visualized.
These parametric map overlaid on the volume rendered images can be manipulated while in motion.
These functional images may be correlated with the lung stiffness.
fig.19 case of normal lung function
fig.20 case of COPD