The PET Scan, a Chemist’s View

This entry is part 2 of 3 in the series "Radiation" --

Liam had a Positron Emission Tomography (PET) scan on 19Sept2014. For this the radioactive tracer is Fludeoxyglucose (18F) or (18F-FDG) for short. For those of you crazy chemistry people out there (like Jenn and myself), check this out:

a)Fludeoxyglucose b) β+ Decay of a proton emits a positron (and changes Fluorine to Oxygen); Since a positron is the antimatter equivalent of an electron, when it finds the closest electron it will annihilate. The matter will cease to exist, and it will turn into energy in the form of light (gamma rays). The two gamma rays produced each will have 511 keV of energy. c) With a little acid, the product will be glucose and continue through the energy cycle in the cell. Until the radioactive decay, the molecule is stuck. There is no chemistry available to the cell to process the glucose with substituted Fluorine, once the F gets converted to a hydroxyl, the chemistry can proceed as normal (With a heavy, but stable Oxygen atom)

The 18F-FDG looks just like the glucose molecule except for a heavy fluorine in place of the  2′ hydroxyl group.  Since all cells use glucose as a power source, the PET scan exploits the fact that cancer cells require more energy, and they will take up more of the compound than normal cells. The areas of the body emitting large amounts of gamma radiation are likely to have concentrations of cancer cells.

For those of you (and I know who you are) who would like even more information, here are some links that I found helpful when I was coming up to speed on the technique:

Fludeoxyglucose (18F)

Positron Emmision Tomography

A Molecular Imaging Primer: Modalities, Imaging Agents, and Applications (scroll down to figure 13)

Decay scheme of 18F

What does it mean to be Liam’s Shield Bearer?







A Stressful Time Back at Home After Round 1

This entry is part 7 of 10 in the series "Liam's Battle" --
A bucket full of Liam's medications

A bucket full of Liam’s medications

The day my son was released from the hospital after his first round of chemo (a 5 day round that with complications led to 22 days in hospital), I came home to find my wife frantically working on Excel with the hustle and bustle of a full house exploding around her. There was a lot going on, but it was clear that what she was doing was important. The kids, who had not seen her in a long time, were siphoned off into another room every time they would show up to hang out with her.

Medicine Delivery Schedule

The Medicine Matrix

What was she doing that was so pressing? She was making a matrix of all of the medications that needed to be administered to Liam.

I found this odd. How many medications had been sent home with him?  Quite a few. When it was broken down on how many doses he is getting a day there are thirty-one.  Thirty-one different things to keep track of. Twenty-nine syringe cleanings. Thirty-one administrations by mouth with differing volume amounts.

As I watched Jenn frantically come to terms with the reality of this situation, i.e. that there were no nurses to administer and keep track of all of the medications that Liam needs, I had the stark revelation that many parents out there must not be able to keep all of this straight.  All that the discharge paperwork said was which medications he was on, the doses per day, and when the last dose was given.

This seems like a poor system.  We have figured it out, but perhaps there is a better way than, “Here you go. Good luck!”

Our experience at Children’s Medical Center has been very positive.  The medical professionals (doctors, nurses, technicians, social worker, child life specialist, music therapists, physical therapists, kitchen staff, janitorial staff, volunteers, etc., etc.) have all been wonderful.  They all created a very safe bubble for Jenn and Liam; however, I think that the transition from the hospital to home has been a little more like the bubble popping than staying in the bubble and floating home on the breeze.

It is good for the two of them to be back home. It has been a wonderful time for me to regain some of the sanity that I had lost, and I enjoy interacting with Liam all of the chances I can get.  When he is home, I get more time with him.

The bubble with all of its iridescent protection returns next Wednesday 21Sept2014 when chemo round 2 starts.

Stem Cells, A Weakened Immune System, and a Dirty House

This entry is part 6 of 10 in the series "Liam's Battle" --
"GCSF Crystal Structure.rsh" by Ramin Herati

“G-CSF Crystal Structure” by Ramin Herati

Liam was allowed to come home for a week before he has to go back in to the hospital for round 2 chemo. Exciting, yes; however, I am forced to look at my home in a different manner.  I have never had to worry about a weakened immune system before.

A typical motto in our house has been, “A few germs will build your immune system.” — You people out there with small kids know what I mean.

A few germs, however,  can be deadly to a little guy that has an impaired immune system.  It is true that after this first round of chemo, his white blood cells are coming back.  But after every successive round of chemo, his immune system will get hammered to the point that it will be close to death (if not dead). So much so, that after the next round of chemo (round 2), they will harvest stem cells from his bone marrow so that they can use them later to reboot his immune system.

The process is pretty neat. They will actually administer a drug (Granulocyte colony-stimulating factor G-CSF) that stimulates the bone marrow to push stem cells out into the peripheral blood.

The collection is performed through a process known as “apheresis.” Blood is drawn and passed into a machine that spins the blood to remove certain stem cells (those identified as “CD34+”), and then the blood is returned to the child. [1]

After the cells have been collected, they will be used during the consolidation phase to give a boost or jump start to the bone marrow.  The autologous (meaning he is his own donor) stem cell transplant will occur under a very strict, positive pressure, wing on the oncology floor.

Having the ability for forward vision, however, only makes me more concerned about what I can do today. While Liam’s immune system is not completely compromised yet, the house as well as the lifestyle of three siblings and a dog have me a bit on edge. What needs to change so that Liam is protected? How do we make it through this time in our life when it seems impossible to keep out external germs while he is at home?

So, the immediate family and myself have spent the day attempting to prepare for Liam’s return to home, albeit for a short while.  We have vacuumed, mopped the floor, washed all of the sheets, removed all that can potentially have germs.  Still, my vision leads me to despair. I know how tiny these bacteria are. I know how my kids will interact with one another.

This problem is beyond me. So, I must keep the cub scout motto in my mind, “Do your best!”  It is all I can do, nothing more.

MetaIodoBenzylGuanidine (mIBG) [update]















