Sanjay Mehta, M.D.

But depending on the risk factors, if it's a very large tumor or if there was a positive central node, maybe an incomplete axillary dissection, in many cases, we end up treating the full axilla. And in some cases, when it's advanced disease, we end up treating level 2 and level 3. So you end up getting the superclav as well.

But depending on the risk factors, if it's a very large tumor or if there was a positive central node, maybe an incomplete axillary dissection, in many cases, we end up treating the full axilla. And in some cases, when it's advanced disease, we end up treating level 2 and level 3. So you end up getting the superclav as well.

This brings up a point I need to kind of emphasize. It's not so much the total dose, it's the dose per fraction. So how quickly are you getting it? So the standard of care was actually 50 gray rather than today's 40-ish gray, but it would usually be given in two gray per fraction daily doses rather than the 2.6, 2.7 that we're using now.

This brings up a point I need to kind of emphasize. It's not so much the total dose, it's the dose per fraction. So how quickly are you getting it? So the standard of care was actually 50 gray rather than today's 40-ish gray, but it would usually be given in two gray per fraction daily doses rather than the 2.6, 2.7 that we're using now.

So the effective dose, when you take into account, there's a whole radiobiology lecture that we're not going to bore people with, but taking into account the dose per fraction and the total dose, the biologically equivalent dose with the BED is roughly the same now at 39.9 gray given in 15 treatments versus the old 50.4 gray that was given in, say, 25 to 28 treatments.

So the effective dose, when you take into account, there's a whole radiobiology lecture that we're not going to bore people with, but taking into account the dose per fraction and the total dose, the biologically equivalent dose with the BED is roughly the same now at 39.9 gray given in 15 treatments versus the old 50.4 gray that was given in, say, 25 to 28 treatments.

So it was a longer process, you're right. And we still do that in some cases. And this comes back to another question you asked about, about the homogeneity of the dose. And so our goal, of course, is to have 100% coverage of the whole breast.

So it was a longer process, you're right. And we still do that in some cases. And this comes back to another question you asked about, about the homogeneity of the dose. And so our goal, of course, is to have 100% coverage of the whole breast.

But the reality is the way that photons are going to be interacting from different beam angles and whatnot, you're always left with hot spots and cold spots. And so the biggest difference between what we're doing now versus the old days wasn't so much the total dose, it was the actual homogeneity that you touched on.

But the reality is the way that photons are going to be interacting from different beam angles and whatnot, you're always left with hot spots and cold spots. And so the biggest difference between what we're doing now versus the old days wasn't so much the total dose, it was the actual homogeneity that you touched on.

So the heterogeneous old way of doing things with a cobalt machine or with a low-energy x-ray unfortunately meant that there were hot spots and cold spots in the breast. And that, of course, could either be manifested as scar tissue if it's a hot spot or, heaven forbid, a geographic recurrence if there was an area that was underdosed.

So the heterogeneous old way of doing things with a cobalt machine or with a low-energy x-ray unfortunately meant that there were hot spots and cold spots in the breast. And that, of course, could either be manifested as scar tissue if it's a hot spot or, heaven forbid, a geographic recurrence if there was an area that was underdosed.

So with the modern computer planning, we're much more homogeneous. So even though you may say, I got 50 gray back in 1995, and now I'm getting 40 gray, you're now getting 40 gray in two and a half gray fractions, which is equivalent to the old 50. Plus, we don't have 150% hotspot and a 60% cold spot. We have a nice 100% match all the way across. It's like a CAD cam type of thing.

So with the modern computer planning, we're much more homogeneous. So even though you may say, I got 50 gray back in 1995, and now I'm getting 40 gray, you're now getting 40 gray in two and a half gray fractions, which is equivalent to the old 50. Plus, we don't have 150% hotspot and a 60% cold spot. We have a nice 100% match all the way across. It's like a CAD cam type of thing.

I'm about as close to an engineer as an MD can be. And so we do actually simulate the dose distribution of the radiation in the tissue. In modern days, we get a nice homogeneous dose. And therefore, that goes to your next question, which was, what does the patient experience?

I'm about as close to an engineer as an MD can be. And so we do actually simulate the dose distribution of the radiation in the tissue. In modern days, we get a nice homogeneous dose. And therefore, that goes to your next question, which was, what does the patient experience?

Maybe not so much 20 years ago, but more like 30, 40 years ago with the older cobalt machines, they would get a terrible dermatitis. Many times it was moist desquamation confluently over the whole chest wall. Axillary desquamation is always bad because of the friction of the arm.

Maybe not so much 20 years ago, but more like 30, 40 years ago with the older cobalt machines, they would get a terrible dermatitis. Many times it was moist desquamation confluently over the whole chest wall. Axillary desquamation is always bad because of the friction of the arm.

But with the modern treatment now with, first of all, not using cobalt, using linear accelerators, the energy of the photons is higher, which means the skin dose is slightly lower. So you're getting maybe 100% on the skin rather than 150% like you once did. So we don't see anywhere near the skin reaction that we used to. It's more of a maybe a grade one or a grade two erythema.

But with the modern treatment now with, first of all, not using cobalt, using linear accelerators, the energy of the photons is higher, which means the skin dose is slightly lower. So you're getting maybe 100% on the skin rather than 150% like you once did. So we don't see anywhere near the skin reaction that we used to. It's more of a maybe a grade one or a grade two erythema.