Conference organizers generated hype around Twitter and pre-announced that Twitterers should include the #RSNA09 hash tag to label their RSNA related tweets. A live feed of #RSNA09 tweets was posted prominently on the main RSNA conference web page. Yellow-shirted Twitter teams walked around the conference to promote the medium by drawing attention to themselves (yellow t-shirts in a sea of suits) and sponsoring Twitter-mediated giveaways. 

As a result, 163 Twitterers sent a combined 857 tweets in the nine days around the official four and a half days of the conference (see Figure 1).  The top 15 Twitterers, who generated over 55% of the total tweets, were overwhelmingly represented by commercial vendors and the RSNA staff (see Figure 2). 

Figure 1: Analysis of tweets containing the #RSNA09 hash tag, decomposed into tweets, re?tweets, and replies.

Figure 2: Top 15 tweeters, re?tweeters and repliers. Analysis of all tweets containing the #RSNA09 hash tag.

A lexical analysis showed that 141/857 (16%) of the #RSNA09 tweets were re-tweets, indicating that one person thought it worthy to repeat what another person had said. An additional 80/857 (11%) of the #RSNA09 tweets were directed at, or explicitly mentioned, another Twitterer. Using the re-tweets and referential/conversational tweets as a measure of social interaction among conference attendees and vendors, this analysis shows that there was only a moderate amount of Twitter-mediated social interaction at RSNA 2009 (27% of all tweets). 

Was Twitter an effective outbound marketing channel at RSNA09? Perhaps; the silent customers, including physicians and hospital administrators, who may have been following the #RSNA09 twitter feed, may have read vendors’ tweets and subsequently followed a hyperlink or visited their exhibit at the trade show. The entry cost for vendors to use this communication channel is negligible and their actions are immediately observable, which facilitates a rapid competitive response (see Figure 3). Yet, the modest level of social interaction suggests that the Twitter audience was not fully engaged by this social technology. 

Figure 3: Three large medical imaging vendors: cumulative tweeting by day at RSNA 2009. Philips and Siemens demonstrated a relatively consistent level of twittering, while General Electric had a surge of activity on the second day of the conference.