Table 1. Descriptions of the parameters used in Eq. (1), with the relevant values for the EMCCD and sCMOS systems.

Parameter	Description	EMCCD value	sCMOS value
QE	Quantum efficiency at peak wavelength	92%	60%
F	Excess noise factor induced by the stochastic process in the electron multiplying register	$\sqrt{2}$	1
T	Image integration time	(varies)	(varies)
D	Thermal noise	0.0002 e-/pixel/s	0.08 e-/pixel/s
C	Charge injection noise	< 0.001 e-/pixel	0
σ	Readout noise	100 e-/pixel	1.5 e-/pixel
G	Amplification gain	Up to 5000	1
IPpIX	Fluorescence signal from PpIX	-	-
IBkg	Non-specific contributions to the signal: autofluorescence and ambient light	-	-
$(I^{\text{PpIX}}+I^{\mathrm{Bkg}})\times QE$	Signal	-	-
$\sqrt{(I^{\mathrm{PpIX}}+I^{\mathrm{Bkg}})\times QE}$	Shot noise	-	-