For Hodgkin lymphoma patients with initial splenic involvement, do you ever include the pre-chemotherapy involved spleen as part of your consolidative ISRT treatment after a CR?

Our long standing policy, first at Yale, for the last 3 decades at Duke, has been to use consolidation RT to all sites of disease known to be present prior to chemotherapy, irrespective of "bulk".   On a log scale little difference between bulk and clinically detectable disease of any size.   The original papers from NCI in the 70's that demonstrated relapse was most likely at sites of original disease did not mention bulk.   So yes, include the spleen after 6 cycles ABVD if it was clearly involved prior to chemo as well as the other sites.   After 6 cycles ABVD, we use 20gy only, again irrespective of bulk.  Our local failure rate less then 5%.  If pt had stage IV disease and we were irradiating organs such as lung or liver, dose should be limited to 13-14gy.  After 4 cycles ABVD German data suggest 30gy is appropriate dose.   We have numerous publications on this - contact me if you need specific references.

Whether to treat above and below diaphragm at the same time depends on the exact areas being treated.   If both fields are relatively small, it is OK.   in the past when treating a mantle and paraaortic nodes and spleen for example they were done separately with a gap of about 3 weeks to allow for marrow recovery and avoid excessive nausea.