For high-through drug screening with organoids or other cell tissues, 2D images of the dye will allow rapid assessment of drug penetration, fraction of drug-resistant cells and level of immune cell activation. However, such accurate quantitative assessment is only possible if the 2D images are converted into 3D profiles. Other than the usual projection effects, 3D transport issues can lead to cell quiescence and low metabolism activity that reduce drug efficacy. Using a diffusion-reaction equation as a model, a code is written to rapidly assess the viability fraction, quiescent cell penetration and overall drug efficacy. This image inversion code should be valuable to any organoid drug screening efforts. In the manuscript, we explain a curious phenomenon that 3D organoids can never achieve 50% inhibition even when the drug dosage exceeds 1000x that of a 2D cell culture. Using the software, the existence of a quiescent cell layer with low metabolism that absorbs the drug but is not inhibited by it is shown to be responsible for this curious phenomenon. In the process, two cancer drugs that can also inhibit quiescent cells are uncovered.