Thumbnail Image Sizing

Hi there,
I love the plugin. I was just wondering though, I have a website which has two distinct shapes of thumbnails: portrait (book covers) and landscape (article and video images). They are in distcint categories and I have set YARPP to pull results that share a category in common. Is there a way that I can have the width set to say 120 px wide and have the height of the images resized respectively?

At the moment half the images are either cut in half or stretched out of proportion.
Thanks
Rhiannon

https://wordpress.org/plugins/yet-another-related-posts-plugin/