Download Radiation Therapy 1.2.3

Radiation Therapy 1.2.3
“Radiotherapy and Radiation Oncology”
hhholdorf
Historical Background
•Radiation therapy uses high-energy radiation to shrink tumors and kill
cancer cells by damaging their DNA
•The field of Radiation Therapy is currently referred to as
Radiation Oncology
•Born not long after the discovery of x-rays in 1895
•by physicist Wilhelm Roentgen
•Many early advocates of Radiation Therapy relied
instead on the placement of
radioactive sources in close
proximity or even within the
tumor, a technique known
as brachytherapy or internal
Radiation therapy
Early Radiation Therapy Machine
Historical Background
• Following World War II, England became the primary focus for research
• Ralston Patterson established the optimal treatment approaches for a wide
variety of tumors undergoing external beam radiotherapy
• Together with the noted Physicist Herbert Parker, Patterson developed the
basic principles underlying brachytherapy prescription, the so-called
“Patterson-Parker Rules”.
• By the 1960s, an exciting development was the introduction of high energy
(megavoltage) treatment machines, known as linear accelerators or linacs
• These machines were capable of:
o
producing high energy, deeply penetrating beams, allowing for the
very first time treatment of tumors deep inside the body without
excessive damage to the overlying skin and other normal tissue.
Ralston Patterson
Historical Background
•A prototype linac was developed by Henry Kaplan and his colleagues at Stanford
University
• The first patient treated using this machine was a child with retinoblastoma (a
cancer of the eye)
• Treatment was highly successful for more than 40 years later, and this patient
remained free of disease with good vision
•Many noteworthy Radiation Oncologists made enormous contributions to the
field of Oncology:
oMalcolm Bagshaw, demonstrated the curative potential of Radiation Therapy in prostate cancer
o Today, based in part on his ground breaking work, radiotherapy is recognized as a mainstay in
the treatment of prostate cancer
o Samuel Hellman, the founding Chair of the Joint Center
for Radiation Therapy was instrumental in establishing
breast conserving therapy (the use of lumpectomy plus
radiation instead of mastectomy) as the treatment of
choice for women with breast cancer
Malcolm Bagshaw
Samuel Hellman
Historical Background
• Radiation therapy began with radium and with
relatively low-voltage diagnostic machines
• A major breakthrough took place when it was
discovered that daily doses of radiation over several
weeks greatly improved the patient’s chance for a
cure
• The methods and the machines that deliver radiation
therapy have steadily improved since the past
• Today, radiation is delivered with great precision to
destroy cancer tumors while limiting damage to
nearby normal tissues
Historical Background
• The type of radiation therapy prescribed by a radiation
oncologist depends on many factors, including:
o The type of cancer
o The size of the cancer
o The cancer’s location in the body
o How close the cancer is to normal tissues that are sensitive
to radiation
o How far into the body the radiation needs to travel
o The patient’s general health and medical history
o Whether the patient will have other types of cancer
treatment
o Other factors, such as the patient’s age and other medical
conditions
Indications for When To Order
• Indications for when
to use radiation
therapy include
shrinking a tumor,
removing a tumor
prior to surgery.
Indications for When To Order
• Radiation therapy is also used in
patients with prostate cancer.
External radiation can be used
by placing the machine outside
the body to send radiation
towards the cancer.
• Internal radiation can also be
used by using a radioactive
substance sealed in needles,
seeds, wires, or catheters that
are placed directly into or near
the cancerous site.
Indications for When Used
• Most common indication for the use of
radiation therapy is to treat cancer.
• Radiation therapy controls, prevents, and kills
cancerous cells in the body.
• It also used to shrink and remove cancer
tumors. Radiation therapy is commonly
applied to the cancerous tumor because of its
ability to control cell growth.
Risks of Radiation Therapy
• Side effects of radiation
therapy greatly depend on
which part of your body is
being exposed to radiation
and how much radiation is
used.
• You may experience no side
effects, or you may
experience several.
• Most side effects are
temporary, can be controlled
and generally disappear over
time once treatment has
ended.
Risks of Radiation Therapy
Part of body being treated
Common side effects
Any part
Hair loss at treatment site (sometimes
permanent), skin irritation at
treatment site, fatigue
Head and neck
Dry mouth, thickened saliva, difficulty
swallowing, sore throat, changes in the
way food tastes, earaches, sore jaw,
nausea
Chest
Difficulty swallowing, cough, shortness
of breath
Abdomen
Nausea, vomiting, diarrhea
Pelvis
Diarrhea, bladder irritation, frequent
urination, sexual dysfunction
Benefits of Radiation Therapy
• The purpose of radiotherapy is to destroy cancer cells while
causing as little damage as possible to normal cells. It can be
used to treat many kinds of cancer in almost any part of the
body.
• Curative treatment, which is sometimes called radical
treatment, aims to give long-term benefits to people.
Sometimes radiotherapy is given on its own or it may be given
alongside other treatment. Radiotherapy may be given before
surgery to shrink a tumor or after surgery to stop the growth of
cancer cells that may remain. It can also be given before,
during or after chemotherapy or hormone treatment to
improve overall results.
• Palliative treatment aims to shrink tumors and reduce pain or
relieve other cancer symptoms. Palliative radiotherapy may
also prolong life.
A Patient Being Put Through the Test
Steps for Ultrasound Examination of Tumors in Breast Cancer Patients involved
in the Case Study:
•
Sonograms were used to measure skin thickness in relation to ultrasonic
(high frequency) waves via the Sequoia 512 scanner machine.
•
A specific type of transducer was set to particular settings, in terms of
gain, depth ranges, and other criteria, such as focal zones, etc. (Refer to
Table 1 of article, An ultrasonographic evaluation of skin thickness in
breast cancer patients after post-mastectomy radiation therapy)
•
Scans used certain magnification levels to zoom in and focus on
particular areas of skin on the patients for precise dimensions and
measurements.
•
Patients were to lie on their backs on a soft surface.
•
Points were placed on each patient’s chest to mark the locations for
sonographic measurements. These areas included medial, lateral, and
midline of the portion of the breast per patient. Points of measurements
were also made on the side of the chest that did not receive RT. This was
to maintain accurate readings of skin thickness measurements for each
patient in the case. (Measured points were marked either 1 cm above or
below initial points only if these points were located directly on the scars
from the mastectomies.)
The Test cont’d
• Transducer lied on a heavy coating of gel to prevent inaccurate
readings of skin thickness measurements.
• All areas of skin were measured in transverse by the same
sonographer.
• Points ranging from the frontal layer of the epidermis toward the
back portion of the dermis area of skin were measured in twodimensional view.
• The points of the breasts that did not receive RT were measured
simultaneously to the points of the radiated breasts.
•
All pictures were then saved for further observations.
The Test cont’d
Steps for Radiation Treatments for Patients diagnosed with Breast Cancer:
•
The participants in the study were to lay on their backs throughout the
procedure.
•
Their arms were to be raised above their heads with bending at the
elbows.
•
A pillow helped support their knees throughout radiation treatment.
•
Treatment points were drawn on each patient’s chest with a marker
surrounding the entire half portion of the thoracic cavity right below the
clavicle.
•
A midline and a line located near the underarm region were also drawn
in relation to marking the finalized area to receive radiation.
•
The entire breast received RT; this included near the underarm area and
near the clavicle for all case study patients.
•
The whole dose was 46-50 Gy provided over a course of about a month
distributed in doses of 2Gy five days per week. (Refer to article.)
•
Doses were given fairly and distributed as equally as possible to all
patients via bolus infusions and highly fixed proportions