The CQC raised concerns over the cleanliness of the critical care unit at Doncaster Royal Infirmary
An NHS trust that runs four hospitals in South Yorkshire and Nottinghamshire has been rated as "requiring improvement".
A report by the Care Quality Commission, external (CQC) said staff vacancies in some areas of Doncaster and Bassetlaw Hospitals NHS Foundation Trust were "impacting on the quality of service".
It also raised concerns over cleanliness and infection prevention.
But inspectors praised the trust over several areas of outstanding practice.
The CQC inspection of the trust, which runs Doncaster Royal Infirmary, Bassetlaw District General Hospital, Retford Hospital and Montagu Hospital in Mexborough, took place in April.
It rated the trust as "requiring improvement" in three out of five categories, but rated it as "good" at caring and for having well-led services.
Among the areas of concern was the potential for people to be unnecessarily exposed to radiation as a result of poor signage around the X-ray department at all four sites.
However, it highlighted the trust being named as the Best Dementia Friendly Hospital in 2013 and its success in managing the abdominal aortic aneurysm screening programme in South Yorkshire.
Chief executive of the trust Mike Pinkerton said: "We welcomed the CQC's scrutiny of our services and we are pleased that they have recognised the many good and outstanding areas of work which takes place in the trust.
"However, the report does identify a small number of areas where improvements can be made in delivering safe, responsive and effective care.
"I am confident we have either already completed, or are well under way in completing the required actions."
He said staff recruitment was a "big challenge" but hoped the trust's overseas recruitment drives would "go some way" to addressing the shortages.
He said signage around its X-ray departments had been improved.
