public void CalculateSSD(DicomImageObject img, float threshold)
{
var p1 = new Point3d(Isocenter.Position.X, Isocenter.Position.Y - SAD, Isocenter.Position.Z);
RTCoordinateTransform T = new RTCoordinateTransform();
T.CollimatorAngle = CollimatorAngle;
T.CouchAngle = CouchAngle;
T.GantryAngle = GantryStart;
Point3d sourcePosn = new Point3d();
T.Transform(p1, Isocenter.Position, sourcePosn);
//Unit vector in direction from source position to isocentre with a length of sampleLength mm
double sampleLength = 2;
double totalLength = (Isocenter.Position - sourcePosn).Length();
int n = (int)totalLength / (int)sampleLength; // the number of steps to sample in the image
var u = sampleLength * ((Isocenter.Position - sourcePosn) / totalLength);
double ssd = 0;
for (int i = 0; i < n; i++)
{
var p = sourcePosn + u * i;
var hu = img.Grid.Interpolate(p);
if (hu.Value > threshold)
{
ssd = i * sampleLength;
break;
}
}
this.SSD = ssd;
}
private Point3d calculateSourcePosition(Beam beam, RTCoordinateTransform transform)
{
var sourcePosn = new Point3d(beam.Isocentre.Position.X, beam.Isocentre.Position.Y - beam.SAD, beam.Isocentre.Position.Z);
var transformedSourcePosn = new Point3d();
transform.Transform(sourcePosn, beam.Isocentre.Position, transformedSourcePosn);
return(transformedSourcePosn);
}
public void Render(Beam beam, Camera camera, IRenderContext context, Rectd screenRect, LineType lineType)
{
var iso = beam.Isocentre.Position;
RTCoordinateTransform transform = new RTCoordinateTransform();
transform.CollimatorAngle = beam.CollimatorAngle;
transform.GantryAngle = beam.GantryStart;
transform.CouchAngle = beam.CouchAngle;
//calculate the initial position from the gantry, couch and sad
var sourcePosn = new Point3d(iso.X, iso.Y - beam.SAD, iso.Z);
transform.Transform(sourcePosn, iso, sourcePosn);
var scrnSource = camera.ConvertWorldToScreenCoords(sourcePosn);
double x1 = beam.XJaw.NegativeJawPosition;
double x2 = beam.XJaw.PositiveJawPosition;
double y1 = beam.YJaw.NegativeJawPosition;
double y2 = beam.YJaw.PositiveJawPosition;
//Draw to middle of each jaw
Point3d X1 = new Point3d(iso.X + x1, iso.Y, iso.Z);
transform.Transform(X1, iso, X1);
var sX1 = camera.ConvertWorldToScreenCoords(X1);
context.DrawLine(scrnSource.X, scrnSource.Y, sX1.X, sX1.Y, DicomColors.Yellow);
//The v coordinates below represent the corners of the jaws projected at isocentre with gantry=couch=coll=0
//v11 means the corner of the jaws x1 and y1
//u is the transformed coordinates
Point3d v11 = new Point3d(iso.X + x1, iso.Y, iso.Z + y1);
Point3d v12 = new Point3d(iso.X + x1, iso.Y, iso.Z + y2);
Point3d v21 = new Point3d(iso.X + x2, iso.Y, iso.Z + y1);
Point3d v22 = new Point3d(iso.X + x2, iso.Y, iso.Z + y2);
Point3d u11 = new Point3d(), u12 = new Point3d(), u21 = new Point3d(), u22 = new Point3d();
transform.Transform(v11, iso, u11);
transform.Transform(v12, iso, u12);
transform.Transform(v21, iso, u21);
transform.Transform(v22, iso, u22);
//We now have four jaw coordinates in the coordinate system.
//Now interesect the line between the source and each coordinates and draw lines between those
Point3d w11, w12, w21, w22;
w11 = camera.Intersect(sourcePosn, u11);
w12 = camera.Intersect(sourcePosn, u12);
w21 = camera.Intersect(sourcePosn, u21);
w22 = camera.Intersect(sourcePosn, u22);
var s11 = camera.ConvertWorldToScreenCoords(w11);
var s12 = camera.ConvertWorldToScreenCoords(w12);
var s21 = camera.ConvertWorldToScreenCoords(w21);
var s22 = camera.ConvertWorldToScreenCoords(w22);
context.DrawLine(s11.X, s11.Y, s21.X, s21.Y, DicomColors.Yellow);
context.DrawLine(s22.X, s22.Y, s21.X, s21.Y, DicomColors.Yellow);
context.DrawLine(s22.X, s22.Y, s12.X, s12.Y, DicomColors.Yellow);
context.DrawLine(s11.X, s11.Y, s12.X, s12.Y, DicomColors.Yellow);
//Draw the line between source and isocentre
var line = (sourcePosn - iso);
if (camera.Normal.Dot(line) == 0)
{
var scrnIso = camera.ConvertWorldToScreenCoords(iso);
context.DrawLine(scrnIso.X, scrnIso.Y, scrnSource.X, scrnSource.Y, DicomColors.Yellow);
}
else
{
//var scrnIso = camera.ConvertWorldToScreenCoords(camera.Intersect(iso, sourcePosn));
//context.DrawLine(scrnIso.X, scrnIso.Y, scrnSource.X, scrnSource.Y, DicomColors.Yellow);
//context.DrawEllipse(scrnIso.X, scrnIso.Y, .02, .02, DicomColors.Yellow);
}
}
