Blood cells are measured in number per volume. Mostly it is count per micro-litre (which is a pretty small volume), I guess your lab is giving the figures with a multipler. Are all you figures formatted OK – maybe 1200, 1200, 920 and 320?

If 0.3210*3/uL is
0.32 x 10^3 lymphocytes per microlitre (=300 per microliter). I had a superscript for the 3 but it was removed when I posted 🙁
(uL is microlitre, also µL or mcL)
What are their reference ranges at you lab? Mine gives 1200-3500. (=1.2 x 10^3 - 3.5 x 10^3)

In the previous study I posted before they use “count per nanoliter” which is a thousand times smaller so the count in your case that would be 0.3.

As to actual risk of infection – I’m not sure – studies are contradictory. Personally, I will be a little more cautious but won’t worry too much about it.
I have a followup appointment (6 weeks post RT) next week and intend to discuss it then (with my new results).
I suggest you talk with your Doctor, but the two I have asked were pretty relaxed about it (at 710).

This study says in the conclusions (and is PCa specific) that there was no additional risk.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9375833/
As a result, there is no significant difference between those that did and did not have radiation. Immunocompromised patients are known to have an increase in opportunistic infections. We could detect no long-term difference in opportunistic infection between those that did and did not receive radiation. We have shown that pelvic radiation has minimal lasting effects on lymphocyte and granulocyte counts. In addition, patients receiving radiation do not appear to be significantly immunocompromised.

However this one found some additional risk. Typical contradictionary conclusions 🙂
This study does have a good graph of lymphocyte count over time which I had not seen elsewhere, but I did not understand their second graph at all (nor how they reached those conclusions)!
https://academic.oup.com/ofid/article/4/suppl_1/S702/4295665?login=false