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RTforHealthCareProfessionals.pptx
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
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
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. 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
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. 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. 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. 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. 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. 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. The Treatment Process
Referral
Consultation
Simulation
Treatment Planning
Quality Assurance
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. 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. 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. 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. 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. 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.
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
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
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. 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. 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
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
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
33. Public Awareness of Radiation
Therapy
Patients report
going to friends
and family and
their referring
physician to get
cancer treatment
information
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. 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
Notes de l'éditeur
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.