Nuclear Associates 76-908 & 76-907
Operators Manual
1.2.1 3D Resolution and Slice (3DRAS) Phantom (Model 76-908)
The 3DRAS phantom has outer dimensions of 6" x 6" x 5" (Figure 1-1). Six resolution inserts and slice thickness 4 ramp sets were placed inside of the rectangular box to allow image acquisition in any one of the three directions (sagital, coronal, and transaxial) without repositioning the phantom.
Outer Shape 6" X 6" X 5" Cubical Box
Figure 1-1. 3DRAS Phantom
The resolution section (Figure 1-2) has square holes of 0.5 mm, 0.75 mm, 1.0 mm and 2.0 mm side dimensions. The spacing between the holes is equal to their side dimensions. The holes are precisely parallel to each other and are ¾” long. Square holes are used rather than drilled cylindrical holes because square holes can be manufactured more precisely than cylindrical holes.
Resolution Block Detail - 2 Required
0.75 x 0.75 mm | 1.0 x 1.0 mm 2.0 x 2.0 mm |
0.5 x 0.5 mm
1”
2 ¼ “
½”
Not to scale
Figure 1-2. Resolution Block Detail
A set of two resolution sections are positioned perpendicular to each other (Figure 1-3) in three imaging planes (sagital, coronal, and transaxial). Two sections are used per imaging plane since the spatial resolution of MR images can be asymmetric between the encoding and frequency (read-out) direction.
1-2
