Calibrating the BI for biological challenge in Autoclave validation

The requirement of F0 = 22.5 minutes originates from the FDA:

TITLE 21–FOOD AND DRUGS
CHAPTER I–FOOD AND DRUG ADMINISTRATION
DEPARTMENT OF HEALTH AND HUMAN SERVICES
SUBCHAPTER F–BIOLOGICS
PART 600 – BIOLOGICAL PRODUCTS: GENERAL

Subpart B–Establishment Standards

Sec. 600.11 Physical establishment, equipment, animals, and care.
(b) Equipment. Apparatus for sterilizing equipment and the method of operation shall be such as to insure the destruction of contaminating microorganisms. The effectiveness of the sterilization procedure shall be no less than that achieved by an attained temperature of 121.5 deg. C maintained for 20 minutes by saturated steam

My interpretation is : 121.5 C in 20 minutes is equivalent to F0 =22.5 minutes.
If the requirement includes SAL overkill.??, then we do not need to reduce the cycle to 119,2 C as the Fbio for the SAL overkill for the BI at 121 is 25.8 minutes > required 22.5. We may hence run the qualification at 121,1 C in 25.8 minutes and when ”No Growth” then the challenge is achieved. Is that correct?. If not, pls explain why?.

To check if the available BI is suitable/can challenge the SAL overkill requirement in the qualification we need to include SAL overkill. Correct?.

The following calculation/statment is wrong:
So, Our MagnaAmp has the following values:
D= 2.1
Z= 8.2
Population: 1.9x10>6
Calculated Fbio : log(1.9x106)* 2.1=13.2 minutes.
Since the calculated Fbio for the BI < the required, the validation should be run at 119.2 C which corresponds to Fbio = 22,5 minutes for the MagnaAmp.

And the following calculation/statment is correct:
Our MagnaAmp has the following values:
D= 2.1
Z= 8.2
Population: 1.9x10>6
Calculated Fbio : (log1.9x106+6)* 2.1=25.8 minutes.
Since the calculated Fbio for the BI > the required, the validation should be run at 121.1 C in 25.8 minutes, when ”No Growth”, then the BI challenge is achieved.

And if we need to qualify a worst case run at approx. 0.5 C below the routin run (121,1-0.5=120.6 C), we must recalculate the Fbio at 120.6 C resulting in 29.8 minutes. And when ”No Growth” at 120.6 C in 29.8 minutes, the challenge of worst Case is acheived. Correct?.
BR//Affe