Well, the bigger issue (speaking for myself, in my personal day-to-day) is not that WE (the physicians) don't understand it's a bad metric, but the admins in our healthcare systems don't understand. "On beam" is very easy to measure, track, and compare to historical numbers - everything admin loves.
On that note - after reading the Todd Lung Tweetorial, I ran the numbers for my own hospital. All of these are true statements:
1) My hospital admin is still using "on beam" to set/track my department's budget.
2) The Lung Math uses an approximate 10-year comparison, 2013 to 2022.
3) 10 years ago, my hospital had one linac and didn't really do SRS/SBRT (small community hospital).
4) Currently, my hospital has two linacs and I frequently do SRS/SBRT.
5) Despite doubling our linear accelerators, our targeted "on beam" number has only increased approximately 30-35%. As we all know, reimbursements in general have been cut over the last 10 years.
6) Running the numbers for patients treated for lung cancer over the last 5 years (I don't have easy access to older data, and I can't drill down on staging easily), it appears my department has treated 33% fewer lung cancer patients, pretty much exactly in line with Todd's estimates. This makes sense, the LDCT recommendations came out in 2014 and needed time to be adopted.
7) I have my hospital's "Standard Charges" list, and I know that SRS and SBRT generate significantly higher reimbursement than conventional fractions. However, as far as I can tell, none of my admins appear to factor this in to their budget math.
8) In terms of total patients simmed per year, we are slightly busier now than 5 years ago, up approximately 12-15%.
9) Like the rest of the country, we have switched from all conventional fractions for breast/prostate to hypofrac for most patients.
10) In a meeting last week, I was told we are several hundred thousand dollars "below our targeted budget".
So we doubled our linacs, but only increased our targeted "on beam" number by 30%, while reimbursements were cut, are seeing less lung patients, using fewer fractions for prostate and breast, started doing a lot of SRS/SBRT which reimburses a lot more, are simming more patients, and being told we're not meeting financial targets, yet there are no tangible consequences for not meeting these targets (no staff have been laid off, no capital expenses denied, etc).
The only conclusion I have: all these numbers are completely invented.
I am incredibly interested to see this ASTRO economics report. Because this is JUST my little community hospital, these are numbers I can personally verify, and none of this makes sense to me.