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  1. 1. An Overview of Radiation Therapy for Health Care Professionals American Society for Radiation Oncology
  2. 2. Introduction  Radiation has been an effective tool for treating cancer for more than 100 years  More than 60 percent of patients diagnosed with cancer will receive radiation therapy as part of their treatment  Radiation oncologists are cancer specialists who manage the care of cancer patients with radiation for either cure or palliation Patient being treated with modern radiation therapy equipment.
  3. 3. Overview  What is the physical and biological basis for radiation  What are the clinical applications of radiation in the management of cancer  What is the process for treatment  Simulation  Treatment planning  Delivery of radiation  What types of radiation are available  Summary
  4. 4. What Is the Biologic Basis for Radiation Therapy?  Radiation therapy works by damaging the DNA of cells and destroys their ability to reproduce  Both normal and cancer cells can be affected by radiation, but cancer cells have generally impaired ability to repair this damage, leading to cell death  All tissues have a tolerance level, or maximum dose, beyond which irreparable damage may occur
  5. 5. Fractionation: A Basic Radiobiologic Principle  Fractionation, or dividing the total dose into small daily fractions over several weeks, takes advantage of differential repair abilities of normal and malignant tissues  Fractionation spares normal tissue through repair and repopulation while increasing damage to tumor cells through redistribution and reoxygenation
  6. 6. The Four R’s of Radiobiology  Four major factors are believed to affect tissue’s response to fractionated radiation:  Repair of sublethal damage to cells between fractions caused by radiation  Repopulation or regrowth of cells between fractions  Redistribution of cells into radiosensitive phases of cell cycle  Reoxygenation of hypoxic cells to make them more sensitive to radiation
  7. 7. Clinical Uses for Radiation Therapy  Therapeutic radiation serves two major functions  To cure cancer  Destroy tumors that have not spread  Kill residual microscopic disease left after surgery or chemotherapy  To reduce or palliate symptoms  Shrink tumors affecting quality of life, e.g., a lung tumor causing shortness of breath  Alleviate pain or neurologic symptoms by reducing the size of a tumor External beam radiation treatments are usually scheduled five days a week and continue for one to ten weeks
  8. 8. Radiation Therapy in Multidisciplinary Care  Radiation therapy plays a major role in the management of many common cancers either alone or as an adjuvant therapy with surgery and chemotherapy  Sites commonly treated include breast, prostate, lung, colorectal, pancreas, esophagus, head and neck, brain, skin, gynecologic, lymphomas, bladder cancers and sarcomas  Radiation is also frequently used to treat brain and bone metastases as well as cord compression
  9. 9. Radiation Therapy Basics  The delivery of external beam radiation treatments is painless and usually scheduled five days a week for one to ten weeks  The effects of radiation therapy are cumulative with most significant side effects occurring near the end of the treatment course.  Side effects usually resolve over the course of a few weeks  There is a slight risk that radiation may cause a secondary cancer many years after treatment, but the risk is outweighed by the potential for curative treatment with radiation therapy {Sabin Motwani will send us image of mild skin redness after RT in a treatment field}. Example of erythroderma after several weeks of radiotherapy with moist desquamation Source: sarahscancerjourney.blogspot.com
  10. 10. Common Radiation Side Effects Side effects during the treatment vary depending on site of the treatment and affect the tissues in radiation field:  Breast – swelling, skin redness  Abdomen – nausea, vomiting, diarrhea  Chest – cough, shortness of breath, esophogeal irritation  Head and neck – taste alterations, dry mouth, mucositis, skin redness  Brain – hair loss, scalp redness  Pelvis – diarrhea, cramping, urinary frequency, vaginal irritation  Prostate – impotence, urinary symptoms, diarrhea  Fatigue is often seen when large areas are irradiated Modern radiation therapy techniques have decreased these side effects significantly Unlike the systemic side effects from chemotherapy, radiation therapy usually only impacts the area that received radiation
  11. 11. Palliative Radiation Therapy  Commonly used to relieve pain from bone cancers  ~ 50 percent of patients receive total relief from their pain  80 to 90 percent of patients will derive some relief  Other palliative uses:  Spinal cord compression  Vascular compression, e.g., superior vena cava syndrome  Bronchial obstruction  Bleeding from gastrointestinal or gynecologic tumors  Esophageal obstruction Radiation is effective therapy for relief of bone pain from cancer
  12. 12. The Radiation Oncology Team  Radiation Oncologist  The doctor who prescribes and oversees the radiation therapy treatments  Medical Physicist  Ensures that treatment plans are properly tailored for each patient, and is responsible for the calibration and accuracy of treatment equipment  Dosimetrist  Works with the radiation oncologist and medical physicist to calculate the proper dose of radiation given to the tumor  Radiation Therapist  Administers the daily radiation under the doctor’s prescription and supervision  Radiation Oncology Nurse  Interacts with the patient and family at the time of consultation, throughout the treatment process and during follow-up care
  13. 13. The Treatment Process  Referral  Consultation  Simulation  Treatment Planning  Quality Assurance
  14. 14. Referral  Tissue diagnosis has been established  Referring physician reviews potential treatment options with patient  Treatment options may include radiation therapy, surgery, chemotherapy or a combination It is important for a referring physician to discuss all possible treatment options available to the patient
  15. 15. Consultation  Radiation oncologist determines whether radiation therapy is appropriate  A treatment plan is developed  Care is coordinated with other members of patient’s oncology team The radiation oncologist will discuss with the patient which type of radiation therapy treatment is best for their type of cancer
  16. 16. Simulation  Patient is set up in treatment position on a dedicated CT scanner  Immobilization devices may be created to assure patient comfort and daily reproducibility  Reference marks or “tattoos” may be placed on patient  CT simulation images are often fused with PET or MRI scans for treatment planning
  17. 17. Treatment Planning  Physician outlines the target and organs at risk  Sophisticated software is used to carefully derive an appropriate treatment plan  Computerized algorithms enable the treatment plan to spare as much healthy tissue as possible  Medical physicist checks the chart and dose calculations  Radiation oncologist reviews and approves final plan Radiation oncologists work with medical physicists and dosimetrists to create the optimal treatment plan for each individualized patient
  18. 18. Safety and Quality Assurance  Each radiation therapy treatment plan goes through many safety checks  The medical physicist checks the calibration of the linear accelerator on a regular basis to assure the correct dose is being delivered  The radiation oncologist, along with the dosimetrist and medical physicist go through a rigorous multi-step QA process to be sure the plan can be safely delivered  QA checks are done by the radiation therapist daily to ensure that each patient is receiving the treatment that was prescribed for them
  19. 19. Delivery of Radiation Therapy  External beam radiation therapy typically delivers radiation using a linear accelerator  Internal radiation therapy, called brachytherapy, involves placing radioactive sources into or near the tumor  The modern unit of radiation is the Gray (Gy), traditionally called the rad  1Gy = 100 centigray (cGy)  1cGy = 1 rad The type of treatment used will depend on the location, size and type of cancer.
  20. 20. Types of External Beam Radiation Therapy  Two-dimensional radiation therapy  Three-dimensional conformal radiation therapy (3-D CRT)  Intensity modulated radiation therapy (IMRT)  Image Guided Radiation Therapy (IGRT)  Intraoperative Radiation Therapy (IORT)  Stereotactic Radiotherapy (SRS/SBRT)  Particle Beam Therapy
  21. 21. Three-Dimensional Conformal Radiation Therapy (3-D CRT)  Uses CT, PET or MRI scans to create a 3-D picture of the tumor and surrounding anatomy  Improved precision, decreased normal tissue damage
  22. 22. Intensity Modulated Radiation Therapy (IMRT)  A highly sophisticated form of 3-D CRT allowing radiation to be shaped more exactly to fit the tumor  Radiation is broken into many “beamlets,” the intensity of each can be adjusted individually  IMRT allows higher doses of radition to be delivered to the tumor while sparing more healthy surrounding tissue
  23. 23. Image Guidance  For patients treated with 3-D or IMRT  Physicians use frequent imaging of the tumor, bony anatomy or implanted fiducial markers for daily set-up accuracy  Imaging performed using CT scans, high quality X-rays, MRI or ultrasound  Motion of tumors can be tracked to maximize tumor coverage and minimize dose to normal tissues Fiducial markers in prostate visualized and aligned
  24. 24. Stereotactic Radiosurgery (SRS)  SRS is a specialized type of external beam radiation that uses focused radiation beams targeting a well-defined tumor  SRS relies on detailed imaging, 3-D treatment planning and complex immobilization for precise treatment set-up to deliver the dose with extreme accuracy  Used on the brain or spine  Typically delivered in a single treatment or fraction
  25. 25. Stereotactic Body Radiotherapy (SBRT)  SBRT refers to stereotactic radiation treatments in 1-5 fractions on specialized linear accelerators  Uses sophisticated imaging, treatment planning and immobilization techniques  Respiratory gating may be necessary for motions management, e.g., lung tumors  SBRT is used for a number of sites: spine, lung, liver, brain, adrenals, pancreas  Data maturing for sites such as prostate
  26. 26. Proton Beam Therapy  Protons are charged particles that deposit most of their energy at a given depth, minimizing risk to tissues beyond that point  Allows for highly specific targeting of tumors located near critical structures  Increasingly available in the U.S.  Most commonly used in treatment of pediatric, CNS and intraocular malignancies  Data maturing for use in other tumor sites Proton Gantry Source: Mevion
  27. 27. Types of Internal Radiation Therapy  Intracavitary implants  Radioactive sources are placed in a cavity near the tumor (breast, cervix, uterine)  Interstitial implants  Sources placed directly into the tissue (prostate, vagina)  Intra-operative implants  Surface applicator is in direct contact with the surgical tumor bed
  28. 28. Brachytherapy  Radioactive sources are implanted into the tumor or surrounding tissue  125I, 103Pd, 192Ir, 137Cs  Purpose is to deliver high doses of radiation to the desired target while minimizing the dose to surrounding normal tissues Radioactive seeds for a permanent prostate implant, an example of low-dose-rate brachytherapy.
  29. 29. Brachytherapy Dose Rate  Low-Dose-Rate (LDR)  Radiation delivered over days and months  Prostate, breast, head and neck, and gynecologic cancers may be treated with LDR brachytherapy  High-Dose-Rate (HDR)  High energy source delivers the dose in a matter of minutes rather than days  Gynecologic, breast, head and neck, lung, skin and some prostate implants may use HDR brachytherapy LDR prostate implant
  30. 30. Permanent vs. Temporary Implants  Permanent implants release small amounts of radiation over a period of several months  Examples include low-dose-rate prostate implants (“seeds”)  Patients receiving permanent implants may be minimally radioactive and should avoid close contact with children or pregnant women  Temporary implants are left in the body for several hours to several days  Patient may require hospitalization during the implant depending on the treatment site  Examples include low-dose-rate GYN implants and high-dose-rate prostate or breast implants
  31. 31. Intraoperative Radiation Therapy (IORT)  IORT delivers a concentrated dose of radiation therapy to a tumor bed during surgery  Advantages  Decrease volume of tissue in boost field  Ability to exclude part or all of dose-limiting normal structures  Increase the effective dose  Multiple sites  Pancreas, stomach, lung, esophagus, colorectal, sarcomas, pediatric tumors, bladder, kidney, gyn  Several recent trials have shown efficacy for breast cancer
  32. 32. Systemic Radiation Therapy  Radiation can also be delivered by an injection.  Metastron (89Strontium), Quadramet (153Samarium) and Xofigo (223Radium) are radioactive isotopes absorbed primarily by cancer cells  Used for treating bone metastases  Radioactive isotopes may be attached to an antibody targeted at tumor cells  Zevalin, Bexxar for Lymphomas  Radioactive “beads” may be used to treat primary or metastatic liver cancer  Y90-Microspheres
  33. 33. Public Awareness of Radiation Therapy  Patients report going to friends and family and their referring physician to get cancer treatment information
  34. 34. Summary  Radiation therapy is a well established modality for the treatment of numerous malignancies  Radiation oncologists are specialists trained to treat cancer with a variety of forms of radiation  Treatment delivery is safe, quick and painless
  35. 35. For More Information…  The American Society for Radiation Oncology (ASTRO) can provide information on radiation therapy  Visit www.rtanswers.org to view information on how radiation therapy works to treat various cancers

Hinweis der Redaktion

  • An introduction to radiation therapy.
  • An overview of topics included in the presentation.
  • Radiation therapy has multiple sources to be used for delivery.
    Most radiation therapy treatments are delivered using photons which are either delivered with Gamma Rays (such as radioisotopes used in brachytherapy) and X-rays (generated by a linear accelerator)
    Additional sources include particle beams such as protons, neutrons and electrons
  • Radiation therapy damages the DNA of cells – normal cancer cells are able to repair themselves but cancer cells have an impaired ability to repair the damage, unlike healthy cells.
  • Between each treatment, healthy cells are able to repair themselves and cancer cells slowly break down. As the cell life continues, the repeated treatments continue to kill the cancer cells as they become sensitive to the radiation.
  • Radiation therapy typically has two primary uses:
    To cure cancer by destroying tumors that have not spread or to kill residual disease left after chemotherapy or surgery
    To reduce or palliate symptoms by shrinking tumors that affect quality of life or alleviate pain or neurologic symptoms by reducing the tumor size
  • Radiation therapy treatment plans often include adjuvant therapies, such as surgery and/or chemotherapy, in order to to enhance its effectiveness and reduce the chance of the tumor recurring.
  • While the delivery of external beam radiation therapy is painless, patients may experience side effects throughout their treatments and at the end. Side effects typically resolve within a few weeks of treatment completion. Side effects can be anything from skin redness in the are treated to GI discomfort.
    There is a risk of secondary cancers from treatment, but the benefits from the potential cure usually far outweighs the risk.
  • Modern radiation therapy techniques have decreased these side effects significantly
  • Palliative radiation therapy is commonly used to relieve pain from bone cancers. It has been shown that 80 to 90 percent of patients derive some relief from this.
    Additional palliative uses include spinal cord compression, vascular compression, bronchial or esophageal obstruction or bleeding from GI for gyn tumors.
  • The radiation therapy treatment team works closely to ensure that patients are receiving safe, quality treatment.
  • Because the referring physician kicks off the treatment process, it is extremely important for the referring physician to have a basic understanding of potential treatment options available.
  • Once a patient has been diagnosed with a cancer, it is important for their referring physician to discuss all of the possible treatment options available to the patient.
  • A radiation oncologist will discuss with the patient if radiation is the appropriate treatment for their cancer. Care is then coordinated with other members of the patient’s oncology team, which could include a medical oncologist or surgical oncologist. It is important for the referring physician to be kept in the loop about the treatment plan.
  • Simulation is an important step in the beginning of the treatment process. The patient is set up for treatment so that immobilization devices can be created, reference marks may be placed on the patient. Measurements and additional scans may be taken at this time.
  • The radiation oncologist works very closely with the medical physicist and dosimetrist to create the optimal individualized plan for each patient.
    The radiation oncologist uses consensus atlases to outline the target and avoidance structures and then uses sophisticated software to create an appropriate treatment plan. Using nationally approved constraints, the treatment team creates a plan that will spare as much healthy tissue as possible.
  • Safety is very important in the delivery of radiation therapy and each radiation therapy treatment team goes through many checks and balances to ensure that patients are receiving the correct dose to the correct area. The radiation oncologist works with the dosimetrist and medial physicist to go through rigourous quality assurance processes to be sure that the radiation therapy plan can be safely delivered.
    In addition, each facility works follows state and federal regulations to help with their checks and balances.
  • Radiation therapy is delivered in two ways, External Beam Radiation Therapy and Internal Radiation Therapy. The absorbed dose is the quantity of radiation absorbed per unit mass of absorbing material. The RAD, or Radiation absorbed dose, is the traditional basic unit. The modern unit is the Gray (Gy), and is defined as 1 joule absorbed/kg. A dose may be prescribed as a Gy or cGy (centigray).
  • Two dimensional radiation therapy uses X-rays to localize tumor. The other types of External Beam Radiation Therapy are much more
  • There are specially designed linear accelerators with built in imaging capabilities that allow for simultaneous imaging to assure precise radiation delivery.
    Motions of tumors can be tracked to ensure that the maximum dose is delivered to the tumor while minimizing dose to the normal tissues.
  • Stereotactic Radiotherapy, commonly referred to as SRS, was developed in 1949 to treat small targets in the brain that could not be surgically removed. It uses a 3-D coordinate system device and fiducial markers, along with specialized immobilization to deliver very precise treatment and is typically delivered in a single fraction.
  • SRS is now more commonly referred to as stereotactic body radiotherapy or SBRT and is used to treat a number of sites in addition to the brain including spine, lung, liver, adrenal, pancreas and prostate)
    There are several external beam machines used to deliver SBRT such as linear accelerators, Cyberknife and Gamma Knife.
    SBRT is typically delivered in a few high-dose fractions.
  • Proton therapy is increasingly becoming available in the United States with more centers opening each year. Protons have historically been used to treat CNS tumors and pediatric cancers.
  • Low-dose-rate brachytherapy is delivered over the course of 48 to 120 hours and is typically used to treat prostate, breast, head and neck and gyn cancers. High-dose-rate brachytherapy is delivered in minutes rather than days and is typically used to treat certain types of gyn, breast, head and neck, lung and skin cancers. Some prostate cancers may be treated with high-dose-rate brachytherapy.
  • Brachytherapy is delivered through permanent or temporary implants depending on the cancer and location. Permanent implants remain in the patient and eventually lose their radioactivity. An example of this is prostate seed implants. Temporary implants may require hospitalization and are left in the body for several hours to days and are then removed. An example of this is high-dose-rate breast implants.
  • Systemic radiation therapy uses radiopharmaceuticals, given by injection or intravenously, that collect where the cancer is and deliver their radiation to kill the cancer cells. Some of the radioactive isotopes used are listed on this slide.
  • ASTRO recently conducted public awareness research on the public’s perception of radiation therapy as a treatment for cancer. The research continues to show that patients typically go to their friends and family, or primary care physician for information and advice when making their cancer treatment decisions.
  • Radiation therapy is safe and effective and should be considered by patients and referring physicians as treatment for numerous cancers.
  • ASTRO has developed patient focused brochures and a website, RTAnswers.org, to provide up-to-date, easy to understand information to help patients make an educated decision when making their treatment decisions.