Final answer:
Positive radiological reports should be referred directly to a medical provider due to the need for clinical expertise and potential immediate medical intervention.
Step-by-step explanation:
The medical assistant should refer calls involving positive radiological reports directly to the provider. Positive radiological reports are significant because they may indicate the presence of a new diagnosis, changes in an existing condition, or require immediate medical intervention. As such, these require the clinical expertise of a provider to interpret and decide on the next steps for patient care.