Radiation Therapy for Cancer Patients

--------- #1416 - Radiation Therapy for Cancer Patients?

- Attachments : none

- Sonoma State University lecture, 2-17-12 , by Joseph Perl of SLAC, Stanford Linear Accelerator. The subject was radiation treatment for cancer patients. Joseph is an expert in particle physics and using GEANT4 software to plot the path of sub-atomic particles to target cancer tumors. Particles must pass through the radiation machinery, air, flesh, bone, muscle, heart, lungs, vessels, etc. Each medium influences the path the radiation particle will take. The goal is to hit the target only and destroy the cancer cells.

- Each atomic particle is like a bullet that we want to aim precisely at a cancer cell. The software calculates the path of the particle then simulates the tracking to the target. Cancer cells are runaway dividing cells and are more susceptible to radiation destruction than normal cells. However, the goal is to kill as few normal cells as possible and at the same time kill 100% of the cancer cells.

- Each type of atomic particle ( radiation ) travels a different distance into the body. Different particle radiations are chosen depending on the type of cancer being treated.

---------------- Electrons that are 4 mega-electron-volts travel the shortest distance into the flesh. This radiation would work for skin cancer.

--------------- X-rays that are 20 mega-electron-volts travel the farthest into the body.

------------- X-rays that are 4 mega-electron-volts travel not as far.

--------------- Protons that are 150 mega-electron-volts travel 15 centimeters into the body and stop. This is the best therapy when there is a need to not damage an organ that is behind the tumor. Proper dosage can gauge the depth of the radiation using protons. Secondary neutron emissions at the target must also be taken into account.

- Proton beams can be sent from several angles to intersect at the target. The software has to plot the path of each projection. Sometimes the calculations can take a super computer up to 250 hours to complete the simulation for one treatment. Each person and each type of cancer requires a custom plan of attack. Often 20 to 40 separate doses are required for one complete treatment.

- The particle paths get even more complicated to calculate because the patient is breathing. Organs, tumors, rib bones are always moving into and out of the path of the particles. This all has to be integrated into the strategy of treatment.

- 23,000,000 Americans are getting radiation treatment for cancer today. Chemotherapy and blunt radiation treatments are crude and overkill for the ideal treatment. This targeted radiation therapy is a revolution in cancer research that can bring precise doses of treatment to the tumor alone. This precise dose treatment is especially critical for children because radiation has long term side effects that can affect a patient in 20 years after treatment. When you are 70 years old it does not matter, but, when you are 7 this is a serious consideration.

- 1,500,000 new cancer patients are diagnosed every year.

- 1,000,000 of these will get radiation treatments each year.

- The radiation therapies range from:

------------------- LINAC
------------------- Cyber Knife
------------------ TomoTherapy
---- -------------- Gamma Knife
------------------- Proton Therapy
------------------- Ion Therapy
------------------ HDR Brach therapy
------------------ radioactive seed implants,( prostrate)

- Some cells are more sensitive to radiation than others. So each type of cancer takes its own therapy strategy. Cells that divide frequently are the most sensitive to radiation. That is why the patient’s hair falls out with treatments. Chemotherapy and radiation therapy work together to optimize the effectiveness of each treatment. Both therapies rely heavily on medical imaging such as:

--------------------- CT , CAT scans
-------------------- MRI
-------------------- PET

-Medical imaging needs to tell radiation therapy the exact location and extent of each tumor in the body.

- The software to plan the radiation particles paths and create the simulations uses the Monte Carlo statistical technique. Each path is broken down into small segments and probabilities are calculated at each step. Multiple steps complete the path. Then, millions of particles are repeated to get a statistical picture of the behavior of the radiation to the target. When the simulation matches the data the therapy for that patient is planned out.

- Proton radiation machines cost $200,000,000. There are less than 20 of these in the U.S.

- Ion radiation machines use heavier particles and they cost $400,000,000 each.

- This amazing Object Oriented software ( C++ ) is free. Anyone can download it off the internet. It does geometry and tracking not just for radiation therapy. It works for Cosmic Ray tracking, for X-ray reflections off the surface of Mercury, for Fermi Gamma Ray telescope design, and any application requiring geometry and tracking. The software is complicated and most users need to attend a 5 day training seminar.

- The group at SLAC is trying to develop a very user friendly version of GEANT4 software for exclusive use in medical proton radiation therapy of cancer patients. 23,000,000 Americans are currently using radiation therapy today and they need quick and reliable implementation of these new innovations to save a life. An announcement will be made shortly, stay tuned.

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707-536-3272, Tuesday, February 28, 2012