Joe L. Meadows, M.S. DABMP Medical Physicist The Lacks Cancer Center Saint Mary’s Health Care Grand Rapids, MI Joe Meadows M.S. ONS Jan.2009 Radiation Therapy 101.5 Jan 20, 2009 Hope Lodge
Objectives <ul><li>Explanation of “radiation” (non and ionizing) </li></ul><ul><li>Review the basic mechanism of radiobiology </li></ul><ul><li>Review of contemporary radiation treatment technologies </li></ul><ul><li>Review of developing technologies in radiation therapy </li></ul>Joe Meadows M.S. ONS Jan.2009
Trust Me I am an Expert! “ An expert is a man who has made all the mistakes which can be made in a very narrow field” Niels Bohr DISCLAMER I am NOT: Physician,Radiobiologist,Pathologist,Epidemiologist or any other “ologist”. I am only a Physicist!
What is “Radiation”?? http://images.google.com/ <ul><li>Radiation is everywhere in the universe. Since the inception of time, lives on earth have been exposed to radiation in the natural environment. </li></ul><ul><li>Radiation is electromagnetic waves (such as light, radiowaves, x-rays, etc.), ultrasound and particles (such as alpha ( ) particles, beta ( ) particles, etc.) emitted by radioactive materials as they decay . </li></ul>
“ Radiation”- Ionizing or Not? http://images.google.com/ <ul><li>Radiation can be classified as non-ionizing and ionizing . In general, the energy of the non-ionizing radiation (such as light and radiowaves) is low energy and not sufficient to change the chemical properties of a substance. (cannot break the chemical bonds). </li></ul><ul><li>Ultrasound is also non-ionizing radiation. </li></ul>A Day At The Beach. What To Wear?? Ultraviolet radiation of the sun is a kind of non-ionizing radiation Non-Physics People Joe
This is a test! Is still “radiation”, but NOT ionizing. It doesn’t have enough energy to break a chemical bond
Ionizing Radiation http://images.google.com/ <ul><li>Ionizing radiation (such as X-rays, , n particles, etc) has energy high enough to remove electrons from an atom to create an electrically charged ion. This ionization process often results in chemical changes in living tissues, which can lead to injury in the organism. Ionizing radiation is generally referred as harmful radiation. </li></ul><ul><li>Radiation cannot be heard, seen, smelled nor tasted. However, with the use of instruments, it can be detected and measured. </li></ul>
X-ray or - ray? http://hko.gov rays and x-rays are similar, the major difference is their origins. rays are emitted from the nuclei of unstable atoms during radioactive decay, while x-rays are from the electron cloud as the result of electron excitation.
Where Does All It Come From? http://hko.gov Percentage of different types of radiation dose in daily life
Does It Matter How Fast You Give It? <ul><li>In general, cells of late-reacting normal tissues are better able to repair sublethal damage than are cancer cells </li></ul><ul><li>There is a “window of opportunity” at low doses (below about 3.5 Gy ) where the survival of late-reacting normal tissue cells exceeds that of cancer cells. </li></ul><ul><li>This is why we have to fractionate radiotherapy at low doses/fraction </li></ul>
Let Me Prove It To You! Sample calculation On second thought, trust me I am a Physicist!
2007 Estimated US Cancer Deaths ONS=Other nervous system. Source: American Cancer Society, 2007. Men 289,550 Women 270,100 26% Lung & bronchus 15% Breast 10% Colon & rectum 6% Pancreas 6% Ovary 4% Leukemia 3% Non-Hodgkin lymphoma 3% Uterine corpus 2% Brain/ONS 2% Liver & intrahepatic bile duct 23% All other sites Lung & bronchus 31% Prostate 9% Colon & rectum 9% Pancreas 6% Leukemia 4% Liver & intrahepatic 4% bile duct Esophagus 4% Urinary bladder 3% Non-Hodgkin 3% lymphoma Kidney 3% All other sites 24%
2007 Estimated US Cancer Cases *Excludes basal and squamous cell skin cancers and in situ carcinomas except urinary bladder. Source: American Cancer Society, 2007. Men 766,860 Women 678,060 26% Breast 15% Lung & bronchus 11% Colon & rectum 6% Uterine corpus 4% Non-Hodgkin lymphoma 4% Melanoma of skin 4% Thyroid 3% Ovary 3% Kidney 3% Leukemia 21% All Other Sites Prostate 29% Lung & bronchus 15% Colon & rectum 10% Urinary bladder 7% Non-Hodgkin 4% lymphoma Melanoma of skin 4% Kidney 4% Leukemia 3% Oral cavity 3% Pancreas 2% All Other Sites 19%
Source: American Cancer Society, 2007. Five-year Relative Survival (%) During Three Time Periods by Cancer Site Better GOOD BAD!! WHY? Site 1975-1977 1984-1986 1996-2002 All sites 50 53 66 Breast (female) 75 79 89 Colon 51 59 65 Leukemia 35 42 49 Lung and bronchus 13 13 16 Melanoma 82 86 92 Non-Hodgkin lymphoma 48 53 63 Ovary 37 40 45 Pancreas 2 3 5 Prostate 69 76 100 Rectum 49 57 66 Urinary bladder 73 78 82
Why Is Lung Cancer Still BAD ? <ul><li>Efforts at early detection have not reduced the deaths </li></ul><ul><li>CXR and bronchial washings have shown limited effectiveness </li></ul><ul><li>Molecular markers in sputum shown promise of earlier diagnosis when surgery is more promising. </li></ul><ul><li>However, surgical risks are still considerable </li></ul><ul><li>In 2002 a collaborative study by the NCI and ACR was launched to access if the screening of high risks patients with spiral CT or CXR will decrease lung cancer deaths. Results expected 2010 </li></ul>
Problems We Are Aware Of? <ul><li>We know the lung (and tumor) is moving </li></ul>
Moving Targets Need “Gating” <ul><li>Respiratory Gating can help mitigate problems of motion </li></ul>Create a movie loop to look for tumor motion. Will determine if delivery will be “TO Gate or NO Gate”. That is the question! Over-sample(1000 slices) and “BIN” Respiratory Pattern
Why Is Lung Cancer Still BAD ? Ask 10 “experts”, get TEN answers!
PET/CT- Metabolic Targeting Functional imaging obtained by PET, which depicts the Spatial distribution of metabolic or biochemical activity in the body which can be precisely aligned with anatomic imaging obtained by CT scanning.
Why Is PET Helpful? Where is the tumor? When the CT alone is used, often time for lung cancer it is difficult (at best) to discern tumor from collapsed lung.
Some Treatment Techniques How we have been treating prostate cancer for the past 25 years using 4 static beams. All the intervening tissues get dosed as well! Today, you can have your treatment on a device that uses THOUSANDS of beams directed at the tumor while missing most of the normal anatomy!
Image Guided Radiotherapy (IGRT) 2D radiographic film 3D Ultrasound Full Helical CT localization
Why Is IGRT Important? Uncorrected treatment Corrected Treatment Note : Large tumor cold spot if treatment is not corrected. If you can’t see what you are doing clearly, you may not get the desired outcome!
What to Do If Feel Lost? If all of this is starting to make your head spin, I have a recommendation for all the Medical Device companies to add this menu to their product
What Is Next- Protons? Due to their relatively enormous mass, protons scatter less easily whereby minimizing lateral damage to surrounding tissue. Furthermore, the dosage to tissue is maximum just over the last few millimeters of the particle’s range; this maximum is called the Bragg Peak . This depth can be optimized to match the tumor depth by varying the proton energy. In theory it is possible to focus the cell damage due to the proton beam at the very depth in the tissues where the tumor is situated; Still River Tomo Proton DWA Mobile Proton Accelerator That’s What I’m Talking About!
What Is Next- Protons? Example : Two Field approach in the head and neck region showing resulting entrance and tumor doses How many proton beam therapy centers are enough? The United States now has 5 in operation with at least 10 more on the horizon. The price tag is mind-boggling, upward of $200 million for a single PBT facility. To justify this huge capital investment, a proton center needs a strategic model, in other words, a high-volume disease, such as prostate cancer. Table 1. Proton facilities operating in the US • The James M. Slater, MD, Proton Treatment and Research Center - Loma Linda, California • Midwest Proton Radiotherapy Institute at Indiana University - Bloomington, Indiana • Francis H. Burr Proton Therapy Center - Massachusetts General Hospital-Harvard, Boston • M.D. Anderson Proton Therapy Center - Houston • University of Florida Proton Therapy Institute - Jacksonville, Florida Selected proton facilities under development in the US • The Roberts Proton Therapy Center at University of Pennsylvania Health System, Philadelphia • Hampton University, Hampton, Virginia • Seattle Cancer Care Alliance • The Oklahoma ProCure Treatment Center, Oklahoma City • Siteman Cancer Center – St. Louis, Missouri. • The Northern Illinois Proton Treatment and Research Center -- Chicago The big advantage of CPT, however, is that as these charged particles traverse through tissue they initially deposit energy at a low LET, followed by a sharp increase to high-LET deposition at the Bragg peak. The tissue depth of this peak can be tailored to each treatment.
Protons- Is it ALL Good? <ul><li>One of the largest hurdles is the cost for a facility. Recent expenditures range 100-150 million per facility! </li></ul><ul><li>There are large biological implications treating with protons, one being the spallation by-products (nuclear fragments) that are NOT currently accounted for in the patient dosimetry and the biological implications are not well known. </li></ul><ul><li>Who is going to pay for this VERY expensive technology that has yet to be proven in a randomized setting? </li></ul>