This is is likely used in a medical context to refer to "pulmonary count rate" or "lung count rate," which involves measuring the radioactivity or specific signals within the lungs using a gamma camera....

pľúcna početnosť refers to monitoring the count rate in the lungs during the inhalation of a product, using a gamma camera equipped with a standard collimator. This is particularly relevant in procedures where radioactive or tracer substances are inhaled, and their distribution and absorption in the lungs are studied for diagnostic purposes.

Here are some of the key examples:
Lung Scintigraphy: In nuclear medicine, lung scintigraphy might involve measuring the "plicní početnost" to assess the distribution of radioactive material in the lungs. This is useful in diagnosing and evaluating conditions such as pulmonary embolism or lung perfusion abnormalities.

Radiopharmaceutical Research: Studies involving new inhalable treatments or diagnostic agents might measure pulmonary count rates to evaluate the efficacy of drug delivery to the lungs.

I also found a relevant reference that may be useful for understanding the use of gamma cameras in measuring lung count rates in nuclear medicine, specifically related to pulmonary ventilation-perfusion (V/Q) scanning, which could relate to the concept of "pulmonary count rate" as discussed earlier.

Lung Ventilation/Perfusion SPECT for Diagnosing Pulmonary Embolism: This article from PubMed discusses the importance of meeting specific count rate ratios in routine lung V/Q SPECT for diagnosing pulmonary conditions like embolism. The focus is on ensuring that the count rate of the perfusion study is at least three times that of the ventilation study to obtain reliable results.
https://pubmed.ncbi.nlm.nih.gov/26392088/

It provides insight into the technical aspects and the importance of count rate measurements in pulmonary diagnostics using nuclear medicine techniques, which might be directly relevant to your inquiry about "pulmonary count rate" or similar concepts.