Fluke Biomedical 37-001 - Manual (Page 5)

Introduction
Introduction
1
1-1
Section 1
Introduction
1.1 Introduction
Precise radiation therapy requires treatment geometry that is accurate and reproducible. Since machine
parameters can easily become misaligned, they should be checked frequently. The TEL-ALIGN™
Teletherapy Alignment Gauge* permits a quick check of these parameters and facilitates the adjustment
of those which require realignment. It is especially useful in an overall QA program.
1.2 Equipment Required
The TEL-ALIGN consists of a rectangular plastic base, 17 cm x 16 cm x 5 cm, with a removable vertical
scale, 18 cm high. The base is placed on the treatment table and leveled, using the adjusting pads and
the circular bubble level. The upper surface of the base contains lead markers that form a square (10 cm
x 10 cm) for visualization on film. A crosshair in the center of the square lines up with two additional sets
of crosshairs, one on each outer edge of the base.
a. TEL-ALIGN Teletherapy Alignment Gauge
b. Ready-Pack Localization Film
1.3 Test Procedure
A. Place the central axis of the gantry in a vertical position. Set all angles (head rotation, gantry,
collimator and treatment couch at 0° position.
B. Set a 10 cm x 10 cm field size at isocenter.
C. Place the TEL-ALIGN base plate on the Mylar portion of the table. Position and level the plate
symmetrically with the 10 cm x 10 cm light field.
D. Position the top surface of the TEL-ALIGN at the isocenter distance.
1.4 Evaluation
A. Optical Distance Indicator (ODI)
Place the vertical ODI scale on the base plate. The coincidence of the machine's ODI scale can
then be checked with the TEL-ALIGN scale. The vertical scale can then be removed.
B. Collimator
Field size and crosshairs should coincide with the TEL-ALIGN, indicating proper alignment. The
symmetry of the collimator jaws, the alignment of the crosshairs, and angle indicators can be
checked at 90° increments by rotating the collimator.
*Designed and developed by the Medical Physics Department, Memorial Sloan Kettering Hospital, New York, NY
10021.