1. An Overview of Radiation Therapy for Health Care Professionals
American Society for Radiation Oncology

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
An introduction to radiation therapy.
Patient being treated with modern radiation therapy equipment.

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
An overview of topics included in the presentation.

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
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.

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. 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
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.

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
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
External beam radiation treatments are usually scheduled five days a week and continue for one to ten weeks

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
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.

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}.
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.
Example of erythroderma after several weeks of radiotherapy with moist desquamation
Source: sarahscancerjourney.blogspot.com

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
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. 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
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.
Radiation is effective therapy for relief of bone pain from cancer

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
The radiation therapy treatment team works closely to ensure that patients are receiving safe, quality treatment.

13. The Treatment Process Referral Consultation Simulation
Treatment Planning
Quality Assurance
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.

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
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.
It is important for a referring physician to discuss all possible treatment options available to the patient

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
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.
The radiation oncologist will discuss with the patient which type of radiation therapy treatment is best for their type of cancer

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
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.

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
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.
Radiation oncologists work with medical physicists and dosimetrists to create the optimal treatment plan for each individualized patient

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
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.

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
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).
The type of treatment used will depend on the location, size and type of cancer.

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
Two dimensional radiation therapy uses X-rays to localize tumor. The other types of External Beam Radiation Therapy are much more

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. 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. 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
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.
Fiducial markers in prostate
visualized and aligned

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
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.

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
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.

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 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.
Proton Gantry
Source: Mevion

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. 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. 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
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.
LDR prostate implant

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
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.

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. 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
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.

33. Public Awareness of Radiation Therapy
Patients report going to friends and family and their referring physician to get cancer treatment information
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.

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
Radiation therapy is safe and effective and should be considered by patients and referring physicians as treatment for numerous cancers.

35. For More Information…
The American Society for Radiation Oncology (ASTRO) can provide information on radiation therapy
Visit to view information on how radiation therapy works to treat various 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.