TO CTDI plus permits the user to measure the dose index for computed tomography systems. The test object consists of three PMMA cylinders, one cylinder represents the paediatric head (100mm diameter), the second the adult head (160mm diameter) and the other represents the body (320mm diameter). The length of each cylinder is 140mm. Each cylinder contains holes large enough to accept a radiation detector, used to take the dose measurements.

There is a hole at the centre of the cylinders and one at each 90° interval, centred 10mm from the edge of the cylinder. This item is available as a nested phantom (the paediatric head phantom fits inside the adult head phantom which fits inside the body phantom).

TO CTDI plus enables the following tests to be made:

• CTDI100 (centre)
• CTDI100 (peripheral)
• CTDIw (weighted CTDI100)
• CTDIvol (weighted CTDIw)
• CTDIfree air

TO CTDI plus is heavy and as such is provided in a tough case with wheels and telescopic handle.

Please note: a CTDI holder is now available for suspension of the TO CTDI plus over the couch end.

SedentexCTIQ consists of a PMMA cylinder (160 mm diameter) with recesses to house test inserts (fig. 1). Within the body of the cylinder are features for the following tests:

• Noise/Uniformity
  The lower section of the phantom is uniform PMMA (density 1.20 +/- 1.00%)
• Geometric Distortion
  An array of 2.0 mm diameter, 3.0 mm deep Air gaps are uniformally pitched at 10.0mm intervals through one slice of the cylinder

Test Inserts are included to perform the following measurements:

• Spatial Resolution
  • Line Spread Function (LSF) – PMMA/PTFE interface (fig. 2)
  • Point Spread Function (PSF) – 0.25mm diameter stainless steel wire suspended in air (fig. 3)
  • LP/mm – alternating Aluminium/polymer (XY)
    (1.0, 1.7, 2.0, 2.5, 2.8, 4.0 and 5.0 LP/mm) (fig. 4)
  • LP/mm – alternating Aluminium/polymer (Z)
    (1.0, 1.7, 2.0, 2.5, 2.8, 4.0 and 5.0 LP/mm) (fig. 5)
• Contrast Resolution (fig. 6)
  1.0, 2.0, 3.0, 4.0, 5.0 mm diameter Al, PTFE, Delrin, LDPE and Air rods suspended in PMMA
• Pixel intensity (fig. 7)
  10.0 mm diameter Al, PTFE, Delrin, LDPE and Air rods suspended in PMMA
• Beam Hardening Artefacts (fig. 8)
  A line of three 5.0 mm diameter rods of Ti suspended in PMMA
• Blank PMMA insert (fig. 9)
• Automatic Scoring Software (available separately)
  See Radia software for more details

The SedentexCT DI dose index phantom comprises a stack of PMMA plates forming a cylinder representing the adult head. Several types of detector system are catered for:

• Ionisation chambers
• Thermoluminescent detectors (TLDs)
• Gafchromic film