AAPM CT Performance Phantom - 76-410-4130
Introduction
The increasing use of computed tomography (CT) as a diagnostic tool creates the need for an efficient means of evaluating the performance of the CT scanners now in use. Recognizing this requirement, the American Association of Physicists in Medicine established the AAPM Task Force on CT Scanner Phantoms. Its goals are to define CT scanner performance and present practical methods of performance testing through the utilization of special phantoms. This phantom design is based on the guidelines presented in Report #1 of the Task Force and approved by the AAPM.
ApplicationsThe modular 76-410-4130 AAPM CT Performance Phantom offers the CT user a single system with which to measure nine performance parameters. This phantom permits the routine standardization of alignment, beam width, spatial uniformity, linearity/contrast, spatial resolution, linespread, noise, size independence, and absorbed dose. All components of the phantom are housed in a compact, transparent tank that holds the system together in the correct orientation.
The phantom consists of an 8.5-inch diameter acrylic tank containing a beam-width insert, a spatial resolution and linespread block, a high-contrast insert, and a means for inserting alignment pins and/or TLD holders. Additionally, a 0.25-inch thick Teflon® band, positioned at the base of the tank and concentric to the 8-inch internal diameter, simulates human bone. Attached to the base of the tank is a low-contrast section with resealable cavities (from 1 in to 0.125 in diameter) which can be filled with a diluted dextrose or other appropriate solution to provide a low-contrast media. The optional external resolution and noise ring slides snugly over the outside diameter of the tank, allowing whole-body scanner systems to be evaluated.
Features- Meets guidelines in AAPM Report No. 1 for Performance Evaluation and QC of CT Scanners
- Single system measures nine performance parameters
- Noise
- Spatial resolution
- Sensitivity (low contrast resolution)
- Absorbed dose
- Size dependence
- Contrast scale
- Slice thickness
- Alignment
- Linearity
- Beamwidth
| Watertank | |
| Material | Made of acrylic |
| Dimensions (ODxIDxL) | (8.5 in x 8 in x 12.75 in) |
| Resealable with fill and drain ports. Low-contrast detectability block is attached to base | |
| Linearity and contrast insert | |
| Dimensions (ODxL) | (7.5 in x 2.5 in) |
| Contains 1 inch diameter contrast pins of polyethylene, acrylic, polycarbonate, polystyrene and nylon. Density values: polyethylene, 0.95 gm/cc; polystyrene, 1.05 gm/cc; nylon, 1.1 gm/cc; acrylic, 1.19 gm/cc; polycarbonate, 1.2 gm/cc | |
| Note: The contrast pins in each AAPM CT Performance Phantom are identical in density to the contrast pins of similar material in every other Fluke Biomedical CT Phantom. For example, the nylon pin in every CT Phantom we manufacture has the same density. | |
| This uniform density among all Fluke Biomedical phantoms provides the user with a standard for comparing the performance of different scanners | |
| Resolution insert | |
| Dimensions (ODxL) | (7.5 in x 2.5 in) with 6 inch diameter solid acrylic block |
| 76-410-4130 | Block has eight sets of five holes: 1.75 mm, 1.5 mm, 1.25 mm, 1.00 mm, 0.75 mm, 0.61 mm, 0.5 mm, and 0.4 mm round |
| In both phantom inserts, the holes are spaced longitudinally on 5 mm centers and vertically on centers equal to twice the hole width. All cavities are filled with air. The 6 inch block is sectored 1.25 inch out on radius. The insert contains 0.014 inch stainless steel wire positioned longitudinally to the insert plates. The wire allows simple computation of linespread functions. A sectored 1.25 inch portion of the main 6 inch block permits an edge gradient to be measured. | |
| Beam width insert | |
| Dimensions (ODxL) | (7.5 in x 3.5 in) |
| Contains three 0.020 in x 1.00 in aluminum strips angled at 45°, positioned on the center line and displayed vertically. A simple, direct calculation permits the accurate measurement of beam width. Adjacency is determined merely by a double exposure of two adjacent frames. | |
| Low-contrast extension | |
| Dimensions (ODxL) | (7.5 in x 3.5 in) |
| Has two each of the following 2.25 inch deep cavities: 1 in, 0.75 in, 0.5 in, 0.375 in, 0.25 in, and 0.125 in diameter, spaced twice the appropriate diameter apart, one row of cavities on each side of the center line. Cavities with screw-locking sealing ports are easily filled with dextrose or sodium chloride solutions of various densities. The user may adjust densities to any value suitable for the scanner. Typically, 2 % or 3 % differentials in density between cavities are used. | |
| Alignment pin | |
| Dimensions (ODxL) | (0.25 in x 3 in) aluminum with tapped hole, allowing pin to be secured to cover plate |
| TLD insert | |
| Dimensions (ODxL) | (0.5 in x 3.5 in) polystyrene rod drilled 3 inch deep to accept TLD inserts |
| Resealable cavity. Tapped on other end to allow mounting to cover plate. | |
| External (whole-body) resolution and noise ring (76-411) | |
| Annulus 12 in OD x 8.5 in ID x 2.5 in long contains the same hole pattern as the Resolution Insert, at two locations 90°°apart. Permits whole-body resolution and noise measurements when positioned on the main tank. Inner and outer resolution values are easily determined. | |
| CT-SSP insert (76-412) | |
| The CT-SSP (Slice Sensitivity Profile) Point Response Phantom can be used as a stand-alone phantom or as an insert with the AAPM CT Performance Phantom. The AAPM CT Performance Phantom meets the guidelines in AAPM Report #1 for Performance Evaluation and QC of CT Scanners. The AAPM CT Performance Phantom is described in the report by the AAPM Task Force on CT Scanner Phantoms. The acrylic and closed-cell foam ball bearing size is 0.01 in, diameter is 7.5 in, width is 3.5 in, and weight is 0.825 lb. | |
| Low-Contrast CT Resolution Insert (76-421) | |
| The insert consists of an almost-water-equivalent plastic disc, 201 mm Ø x 25 mm thick, protected on both sides by clear plastic. The resolution targets are a series of water-filled holes from 2.5 mm to 7.5 mm in Ø, in 0.5 mm steps. For each target size, the center-to-center distance between holes is twice the hole diameter to ensure meaningful resolution testing. The insert's 25 mm thickness eliminates alignment problems. Dimensions are 201.6 cm x 32.5 cm thick. Weight is 1 lb. | |
| Dimensions (ØxD) | 21.59 cm x 39.37 cm (8.5 in x 15.5 in) |
| Weight | 7.84 kg (17.25 lb) |
| Models | |
| Number | Description |
| 76-410-4130 | AAPM CT Performance Phantom with Resolution Insert (to 0.4 mm) |
| Optional Accessories | |
| 76-411 | External (Whole-Body) Resolution and Noise Ring |
| 76-412 | CT-SSP Point Response Phantom |
| 76-421 | Low-Contrast CT Resolution Insert |