Monday, October 7, 2013

X-Ray Specs

I've been meaning to post these images for a couple of months now but never had the energy or priority until now. I'm feeling slightly more energetic today (maybe 20%?) so here you go.

We developed a great relationship with Dr. Rad, the Radiation Oncologist who treated me. We saw her every Thursday during the seven weeks of radiation plus several follow-ups. We see her again next week.

I was fascinated by the treatment planning process. She was surprised by my knowledge of the area (I worked a lot in medical imaging in the 1990's). Toward the end of treatment, she spent about half an hour with me showing me the treatment planning software and the details of my particular treatment plan.

For a refresher on how IMRT (Intensity-Modulated Radiation Therapy) works, see this post.

The most important part is that the doctors are able to shape the radiation beam somewhat precisely. They can deliver maximum dose to the tumor but almost no radiation to critical structures that are very nearby. That is called "treatment planning". The images below are screen shots from the treatment planning software. Most patients would never see them.

Click any image to embiggen.

Figure 1

Figure 1 is obviously a side view. The colors indicate radiation dose to be delivered. You can see that the base of my tongue was heavily infiltrated by the tumor. In this image, the lymph node is superimposed on the tumor so the outline of the pink thing is not necessarily exactly the tumor outline.

Note that there is a hard boundary in front of my spine. There is also a gap in the front of my throat. This is referred to as the laryngeal block - they don't want to deliver any radiation to my voice box. It is fragile. The green spot at the bottom is the lower portion of the zone that includes all of the lymph nodes in my neck. You'll see that zone better in a later image.

Figure 2

Figure 2 is a front view. The black color is air, so you're seeing my nasal cavity, throat and esophagus (and lungs).

The pink area of highest desired dose is the tumor and surrounding tissue, plus Lumpy the Lymph Node and nearby tissues.

There are several dozen lymph nodes in the neck and they want to treat them all aggressively. The lymph nodes are the first place the cancer moves to when it metastasizes and there could be cancer "seeds" in any of those nodes. The blue zone is encompassing all of those nodes, with the green area delivering a slightly lower dose to surrounding tissues.

In Figure 2 you can clearly see the laryngeal block, sparing my voice box.

Figure 3

Figure 3 is looking down through my head (or up, it doesn't matter).

This image clearly shows just how big Lumpy the Lymph Node was. It also shows that Pappy the Papilloma (the tongue tumor) was larger than I imagined.

In Figure 3 you can also see again how the radiation beams are shaped to avoid irradiating my spine.

Figure 4

Figure 4 really shows the full extent of the treatment field. Note that it reaches all the way past my collarbones.

You can see the blue and green zones that are covering all of the lymph nodes in the neck, and you can see the laryngeal block.

This particular slice happens to not pass through the tumor. Since we can see some of my spine, we can tell that this slice is just behind the back of my throat.

So there you go. Now you know exactly which parts of me were killed with radiation. No wonder the outside of my neck is still puffy and recovering.

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