CT scan with barium next week + IBS is not a good mix

I was diagnosed with IBS-D over 30 years ago and it's getting worse. I have to go many times a day. I've been having a change in bowel habits that worry me. Constipation is happening more frequently than it used to, lots of straining, incomplete evacuation etc. I have a large ventral hernia too and that may be making this worse.

To make a long story short, I have a CT scan with barium contrast next week. The last time I had one of those I bare!y made it off the table before having to run to the bathroom with severe diarrhea. I can't bear the thought of going through that again.

My primary care doctor said that I can take a couple of Imodium tablets before the test and the imaging center agreed but it's been my experience that stuff rarely works for me.

Does anyone have suggestions on how to overcome this? I thought about doing a liquid diet the day before. And perhaps some laxatives the day before that. I'm worried because I can't control my bowels as much as I used to and I'm taking a wheelchair bus to and from the appointment. I don't want to have an accident. Thank you.