def searching_for_ring(vol, sampling, center_point, global_direction, \
look_for_bifurcation, average_radius, alpha, ring):
"""
Given a center point and a direction, the algorithm will start by searching
for points in a certain stent ring using the global direction. By connecting
points it will come to a set of nodes. After a certain amount of nodes are
found, the algorithm will flip the direction and will search for points in
the other direction until the stent ring is defined. The radius is used when
searching for the bifurcation.
"""
#Initially, the bifurcation is not found
found_bifurcation = False
#First the initial center point and direction has to be stored in order to
#flip the direction later
stored_center_point = center_point
flipped_global_direction = -1 * global_direction
#Create pointsets to store points
node_points_ring = Pointset(5) #(z,y,x,ring,direction)
stent_points_ring = Pointset(3)
center_points_ring = Pointset(3)
#Expected amount of nodes and returns initial filtered points
expected_amount_of_nodes, initial_points_in_slice = amount_of_nodes(vol, sampling, \
center_point, global_direction, look_for_bifurcation)
#set direction: 1 for along the direction of the stent, -1 for the opposite \
#direction
direction = 1
#Find and connect points
center_points, stent_points, node_points, global_direction, found_bifurcation, new_starting_positions, \
ring = connecting_stent_points(vol, sampling, center_point, global_direction, look_for_bifurcation, \
average_radius, direction, expected_amount_of_nodes, initial_points_in_slice, found_bifurcation, alpha, ring)
#Store starting positions, because the direction -1 will remove otherwise.
if found_bifurcation:
store_starting_positions = new_starting_positions
#Add found points to pointsets
node_points_ring.Extend(node_points)
stent_points_ring.Extend(stent_points)
center_points_ring.Extend(center_points)
#Store last center point to use as 'jumping' site
if len(center_points_ring):
jump_location = center_points_ring[len(center_points_ring) - 1]
else:
jump_location = stored_center_point
jump_direction = global_direction
#Flip direction
direction = -1
#Find and connect points for other direction
center_points, stent_points, node_points, global_direction, found_bifurcation, new_starting_positions, \
ring = connecting_stent_points(vol, sampling, stored_center_point, flipped_global_direction, \
look_for_bifurcation, average_radius, direction, expected_amount_of_nodes, \
initial_points_in_slice, found_bifurcation, alpha, ring)
if found_bifurcation:
new_starting_positions = store_starting_positions
#Add found points to pointsets
node_points_ring.Extend(node_points)
stent_points_ring.Extend(stent_points)
center_points_ring.Extend(center_points)
ring = ring + 1
return node_points_ring, stent_points_ring, center_points_ring, \
jump_location, jump_direction, found_bifurcation, new_starting_positions, ring
def stent_detection(vol, sampling, origin, seed_points):
"""
This is the function that will be called in order to extract the stent
from the CT data.
"""
#Point set where the final points will be stored. In node, the 4th number
#indicates the ring number, the 5th indicates the direction where it is found
node_points_stent = Pointset(5)
center_points_stent = Pointset(3)
stent_points_stent = Pointset(3)
#Initially, the bifurcation is not found
found_bifurcation = False
average_radius = []
#start with ring 1
ring = 1
#Weighting factor alpha
alpha = ssdf._stent_tracking_params.weighting_factor
distance = ssdf._stent_tracking_params.distance
#From seed point to seed point except for the last seed point, where the
#bifurcation needs to be found.
for i in range(len(seed_points) - 2):
round = 0
#Don't look for the bifurcation when not connecting points in the last
#part of the stent
look_for_bifurcation = False
#Get initial center point and direction using the seed points
center_point, global_direction = initial_center_point(
vol, seed_points[i], seed_points[i + 1], sampling, origin, alpha)
#While the center point has not passed the seed point
while center_point[0] < seed_points[i + 1][0] and round < 10:
#Find stent, node and center points for a certain stent ring
node_points_ring, stent_points_ring, center_points_ring, \
jump_location, jump_direction, found_bifurcation, new_starting_positions, \
ring = searching_for_ring(vol, sampling, center_point, global_direction,\
look_for_bifurcation, average_radius, alpha, ring)
#Set new starting center point inside the new ring
center_point = jump_location + distance * Point(
jump_direction[2], jump_direction[1], jump_direction[0])
global_direction = jump_direction
#Add points to point sets
node_points_stent.Extend(node_points_ring)
center_points_stent.Extend(center_points_ring)
stent_points_stent.Extend(stent_points_ring)
round = round + 1
#For the last part of the stent where the bifurcation needs to be found
for i in range(len(seed_points) - 2, len(seed_points) - 1):
#Reset round to zero
round = 0
look_for_bifurcation = True
center_point, global_direction = initial_center_point(vol, seed_points[i],\
seed_points[i+1], sampling, origin, alpha)
#While the bifurcation is not found
while found_bifurcation == False and round < 10:
node_points_ring, stent_points_ring, center_points_ring, \
jump_location, jump_direction, found_bifurcation, new_starting_positions, \
ring = searching_for_ring(vol, sampling, center_point, global_direction, \
look_for_bifurcation, average_radius, alpha, ring)
center_point = jump_location + distance * Point(
jump_direction[2], jump_direction[1], jump_direction[0])
global_direction = jump_direction
#Add points to point sets
node_points_stent.Extend(node_points_ring)
center_points_stent.Extend(center_points_ring)
stent_points_stent.Extend(stent_points_ring)
round = round + 1
#Store new starting positions in another poitset, because algorithm will
#return [] as new_starting_positions.
starting_positions = Pointset(3)
#For the case where there is no bifurcation present
try:
starting_positions.Append(
new_starting_positions[0]
) # + distance * Point(jump_direction[2],jump_direction[1],jump_direction[0]))
starting_positions.Append(
new_starting_positions[1]
) # + distance * Point(jump_direction[2],jump_direction[1],jump_direction[0]))
except IndexError:
[]
alpha = ssdf._stent_tracking_params.weighting_factor_bif
#Now points after the bifurcation will be found
for i in range(len(starting_positions)):
center_point = starting_positions[i]
look_for_bifurcation = False
round = 0
while round < 4:
node_points_ring, stent_points_ring, center_points_ring, \
jump_location, jump_direction, found_bifurcation, new_starting_positions, \
ring = searching_for_ring(vol, sampling, center_point, global_direction, \
look_for_bifurcation, average_radius, alpha, ring)
center_point = jump_location + distance * Point(
jump_direction[2], jump_direction[1], jump_direction[0])
global_direction = jump_direction
if 255 < center_point[0]:
break
#Add points to point sets
node_points_stent.Extend(node_points_ring)
center_points_stent.Extend(center_points_ring)
stent_points_stent.Extend(stent_points_ring)
round = round + 1
return node_points_stent, center_points_stent, stent_points_stent
def connecting_stent_points(vol, sampling, center_point, global_direction, look_for_bifurcation, \
average_radius, direction, expected_amount_of_nodes, points_in_slice, found_bifurcation, alpha, ring):
"""
This algorithm uses the earlier stated functions in order to connect points
and define nodes.
"""
#Nodes that are found for the current direction
node_points_direction = Pointset(3)
#Other pointsets to store points
center_points = Pointset(3)
stent_points = Pointset(3)
node_points = Pointset(5)
#Set round to 0 for the case that the amount of nodes criterion is not met.
round = 0
#Initial
new_starting_positions = []
#connecting points
while len(node_points_direction) < expected_amount_of_nodes and round < 12:
#Get slice
slice, center_point, global_direction, rotation_point, vec1, vec2, \
center_point_3d_with_radius = centerline_tracking.get_slice(vol, sampling, \
center_point, global_direction, look_for_bifurcation, alpha)
#If looking for the bifurcation, check radius
if look_for_bifurcation and direction == 1:
if not found_bifurcation:
average_radius, found_bifurcation, new_starting_positions \
= check_for_possible_bifurcation(average_radius, center_point_3d_with_radius, \
rotation_point, found_bifurcation, global_direction)
else:
new_starting_positions = []
#Find points
points_in_next_slice = stentPoints2d.detect_points(slice)
#Find connecting points. Change not connecting points into virtual points
connecting_points, virtual_points = find_connecting_points(points_in_slice, \
points_in_next_slice)
#Check if virtual points should be converted into connecting points
connecting_points, temp_slice = check_virtual_points(virtual_points, \
connecting_points, center_point, vol, sampling, global_direction, alpha)
#Check for nodes
point_nodes_2d, point_remove = check_for_nodes(connecting_points,
temp_slice)
#If nodes are found, these points should be deleted from the connecting points list
connecting_points = delete_nodes_from_list(connecting_points,
point_remove)
#Convert 2d points into 3d points
connecting_points_3d = convert_2d_point_to_3d_point(center_point, vec1,\
vec2, connecting_points)
point_nodes_3d = convert_2d_point_to_3d_point(center_point, vec1, vec2,\
point_nodes_2d)
#Add 3d points to their list
center_points.Append(rotation_point)
stent_points.Extend(connecting_points_3d)
node_points_direction.Extend(point_nodes_3d)
for i in range(len(point_nodes_3d)):
node_points.Append(
Point(point_nodes_3d[i][0], point_nodes_3d[i][1],
point_nodes_3d[i][2], ring, direction))
#Set connecting points as new base points
points_in_slice = connecting_points
#Next round
round = round + 1
#If there are three nodes found, do first one more run.
if len(node_points_direction) > 2:
diff = 10 - round
if diff > 0:
round = round + diff
if round == 12:
new_nodes = additional_nodes(connecting_points_3d)
for i in range(len(new_nodes)):
node_points.Append(
Point(new_nodes[i][0], new_nodes[i][1], new_nodes[i][2],
ring, direction))
return center_points, stent_points, node_points, global_direction, found_bifurcation, new_starting_positions, ring
