Medical Imaging Alignment Systems

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Which axis represents the patient's right to left direction?

Gantry

Z-axis

Y-axis

X-axis (correct)

What does a negative number on the y-axis indicate?

Cephalad direction

Caudal direction (correct)

Anterior direction

Posterior direction

Which machine component rotates around a vertical axis when the gantry is in the 0-degree position?

Gantry

Collimator (correct)

Couch

None of the above

What is the usual degree position for the gantry rotation?

0 degrees Signup and view all the answers

Which axis in the patient represents the horizontal axis around which the gantry rotates?

Y-axis Signup and view all the answers

Why is consistency necessary in the orientation of axes with respect to the patient?

To align the patient for treatment accurately Signup and view all the answers

What is the purpose of the graticule in the beam during treatment simulation?

To display a scale used for magnification Signup and view all the answers

During the simulation procedure, what is determined by measuring the distance from the origin of the coordinate system indicated by reference marks?

Right/left direction Signup and view all the answers

In treatment simulation, why must the marks made on the patient during data acquisition be realigned with the alignment system?

To ensure accurate delivery of treatment Signup and view all the answers

What is used as a magnification device for transposing internal information onto a transverse contour of the patient?

Graticule Signup and view all the answers

Which component of the treatment machine determines the angle from which radiation is delivered to the patient?

Gantry Signup and view all the answers

What is crucial in determining the central axis and extremes of the desired treatment field under fluoroscopic visualization?

Reference marks on the patient Signup and view all the answers

What is the intersection of the horizontal and vertical axes of rotation referred to as?

Isocenter Signup and view all the answers

Why are alignment systems essential in radiation therapy?

To ensure patient repositioning accuracy Signup and view all the answers

What is necessary in an alignment system to ensure proper alignment with the sagittal, coronal, and axial planes?

Lines intersecting at the isocenter and in parallel with the anatomical planes Signup and view all the answers

In which plane is a contour most frequently obtained for treatment planning purposes?

Transverse plane at the beam central axis Signup and view all the answers

For which field arrangement in radiation therapy is dose typically prescribed at middepth on the central axis?

Opposed fields Signup and view all the answers

Why might it be necessary to obtain contours in multiple planes in areas with irregular external surfaces?

To ensure accurate dose delivery to irregular surfaces Signup and view all the answers