Dose Rate Control setting Optimus for Computed Radiography (PCR or other imaging plates)

Select:
Optimus (XRG90) >> Program >> Dose Rate Control >> AMPLIMAT >> Chamber 1...5 >> Data Set 1...5>> DRC Handling:
Start Automatic DRC Processing >> <OK>

The following example is for a 400 speed system, determined by the selection of the LG06 400 speed type from file LUMAT_LG.TDL (luminous groups).
Ignore the violet screen colour of LG06, the data set just requires its kV characteristic.

FILM: Select from FILM.TDL : X-CONSTANT RLF=1
SCREEN: Select from LUMAT_LG.TDL : LG06 S400 vi
CHAMBER: Select from CHAMBER.TDL : the installed chamber type
CASSETTE: Select from CASSETTE.TDL : normal cassette(def)
SYSTEM CORRECTION: Select from SYSCOR.TDL : no corr.(ISO9236-1)
CORRECTION FACTOR: 1.00

Transmit the screen with <F2>.

Call the same Data Set >> DRC Handling: Start Automatic DRC Processing >> again, but now use <ESC> to open the data set screen:

Two data fields can be modified, all others must not be changed:

> Abbreviation: Any name up to six characters can be given. The abbreviation name should indicate the programmed speed type if different speeds shall be used with the same imaging plates.

Dose of FSC [µGy]: Use Ks explanation this page. The value can be adapted to the local "density taste".

All other data (kV70-Char. and RLF) must remain as they have been calculated during the programming and loading process to obtain the chamber type + imaging plate depending kV characteristic. RLF is constant = 1.

Formula to determine the speed = S of a film-screen-combination:

K0 1000 µGy >> use speed as !! S = speed must not be mixed up !!

S = ------- = --------------------------- >> abbreviation !! with S = sensitivity PCR !!

Ks Dose of FSC [µGy]: >> name

K0 is a constant with a value of 1000 µGy.

Ks is a variable value principally representing a switch off dose to obtain a density of 1.0 above base and fog, (normal films determined by the manufaturer of a film-screen system for defined processing conditions which are different in a computed RAD system). Can be adapted to the local "density taste"

If e.g Ks = 2.5 µGy (like the example of the previous page)

1000 µGy

S = = 400

2.5 µGy

Range of speed values S within the standard speed class SC systems:

only valid for film-screen-combinations for an optical density of 1.0
Speed class SC Standard | dose / exposure [µGy] Standard class SC | Speed value S Range
6 | 167 | 5 - 9
12 | 83 | 10 - 18
25 | 40 | 20 - 36
50 | 20 | 40 - 71
100 | 10 | 80 - 140
200 | 5 | 160 - 280
400 | 2.5 | 320 - 560
800 | 1.25 | 630 – 1100
1600 | 0.625 | 1250 – 2200

If different speeds shall be used copy one screen with <F3> and load it to all other data sets of the chamber with <F4>. Change Abbreviation names and Dose of FSC values accordingly afterwords

To complete the overview of the entire data set screen:

More information available in booklet "Radiographic screens and films", manual order No. 4512 980 50592.