IEC 60336:2020 applies to FOCAL SPOTS in medical diagnostic X-RAY TUBE ASSEMBLIES for medical use, operating at X-RAY TUBE VOLTAGES up to and including 150 kV. This document describes the test methods employing digital detectors for determining: a) FOCAL SPOT dimensions in terms of NOMINAL FOCAL SPOT VALUES, ranging from 0,1 to 3,0; b) LINE SPREAD FUNCTIONS; c) one-dimensional MODULATION TRANSFER FUNCTIONS; d) FOCAL SPOT PINHOLE RADIOGRAMS, and the means for indicating compliance. In informative annexes, STAR PATTERN imaging and BLOOMING VALUE are described. IEC 60336:2020 cancels and replaces the fourth edition published in 2005. This edition constitutes a technical revision. The significant changes of this fifth edition with respect to the previous edition are detailed in Clause E.6. These changes are: a) introduction of digital detectors and discretization errors; b) fewer normative requirements; c) support for both SLIT CAMERA and PINHOLE CAMERA; d) reintroduction of distorted (skewed) FOCAL SPOT; e) keeping of STAR PATTERNS and BLOOMING VALUE as informative.