radiation therapy 1.2.3 hhholdorf “radiotherapy and radiation oncology”

15
Radiation Therapy 1.2.3 hhholdorf “Radiotherapy and Radiation Oncology”

Upload: jeremy-brown

Post on 22-Dec-2015

236 views

Category:

Documents


3 download

TRANSCRIPT

Radiation Therapy 1.2.3

hhholdorf

“Radiotherapy and Radiation Oncology”

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: o Malcolm Bagshaw, demonstrated the curative potential of Radiation Therapy in prostate cancero Today, based in part on his ground breaking work, radiotherapy is recognized as a mainstay in

the treatment of prostate cancero Samuel Hellman, the founding Chair of the Joint Center

for Radiation Therapy was instrumental in establishing breast conserving therapy (the use of lumpectomy plusradiation instead of mastectomy) as the treatment of choice for women with breast cancer

Malcolm Bagshaw Samuel Hellman

• 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 cancero The size of the cancero The cancer’s location in the bodyo How close the cancer is to normal tissues that are sensitive

to radiationo How far into the body the radiation needs to travelo The patient’s general health and medical historyo Whether the patient will have other types of cancer

treatment o Other factors, such as the patient’s age and other medical

conditions

Historical Background

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 TherapyPart of body being treated Common side effects

Any partHair loss at treatment site (sometimes permanent), skin irritation at treatment site, fatigue

Head and neckDry 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 TestSteps 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

two-dimensional 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’dSteps 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