Radiology Letters of Recommendation

I know the consensus is that clinical letters are important but people also say that radiology letters are important as well. Does this matter where the clinical letters are from? For example, if I obtain a pediatrics letters of recommendation would this be as strong as a radiology or internal medicine one? Is it three letters maximum or three letters minimum?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Tags: Radiology Source Type: forums