InnoVet Select
™
HF APR
Service Manual
62
IMPORTANT: Due to kW limits, exposures at 125 kVp/250 mA, 110 kVp/300
mA and 125 kVp/300 mA are not possible. Change the filament value
numbers at these points as needed to reflect the pattern of values established
at other points. Example: 110 kVp/300 mA will typically be .02 less than the
value at 90 kVp/300.
Note: At lower power levels the mA leading edge may have a one-millisecond
spike of no more than 50 mA. This is from cable capacitance, and can not be
adjusted out by the master or individual filament value numbers.
8.
The Filament Number Table and Recording Calibration Values.
All of the filament numbers can be viewed at one time by selecting the XRAY CAL
screen. Selecting FIL# TBL will display all of the numbers that control mA leading
edge, with the mA stations in columns and the kVp stations in rows. Notice how the
numbers neatly decrease as kVp increases (space charge compensation) and how
for a given kVp the values increase as mA increases.
Table 9-1: Typical Filament Values for a Toshiba 1 x 2 mm X-ray Tube
FIL #
TABLE
50 mA
100 mA
150 mA
200 mA
250 mA
300 mA
40 kVp
4.30 4.57 4.54 4.64 4.74 4.83
50 kVp
4.28 4.54 4.51 4.61 4.71
4.79
70 kVp
4.26 4.50 4.46 4.56 4.66 4.73
90 kVp
4.24 4.47 4.43 4.53 4.62 4.70
110 kVp
4.22 4.44 4.40
4.50
4.60
4.67*
125 kVp
4.20 4.42 4.38 4.48 4.57*
4.64*
* Exposure is not possible at these techniques. Enter values, which follow the
pattern established at lower kVp for the mA station.
Each tube type has individual default filament numbers. These tube specific
defaults will likely be changed during calibration. This chart is shown for reference
only, not as a site-specific calibration record. The actual filament amps required at
this installation will be determined during calibration.
