Noticed our chest room’s AEC is delivering 8–10% higher DAP than our March baseline with a 20 cm PMMA phantom at 110 kVp — no changes to filtration or target EI. Before I schedule a recalibration, what action level are you using to keep accuracy tight without letting dose creep — 5% or 10%?
I’d “trust but verify”: use ±5% as the internal action level and ±10% as a hard fail, but first cross-check the room’s DAP with an external meter and spot-check kVp/HVL — DAP heads drift like bathroom scales. If the independent check confirms the 8–10%, run a quick three‑chamber AEC constancy at 110 and 80 kVp to see if it’s chamber‑specific; seeing any EI shift or histogram oddities?
And could be the weight, but the 6 p.m. temp drop can mimic that shift too — next lap, jot pressures and repeat the cloverleaf with and without the “28 lbs” at the same time, or try +1 psi rear to simulate it; the dog’s now your tuning partner. @derekb2000’s tie-down idea is solid for repeatability — what pressures were you running?