• 3D-CRT uses a ________collimator (MLC) in a step-and-shoot technique

is a radiation therapy technique that involves CT/MRI/ PET Scan planning where the volume to be treated is defined on a 3D data set

• A multi-leaf collimator typically consists of __________ tungsten leaves, which can move independently into the beam path and thus create nearly limitless beam shapes

TRUE OR FALSE • Goal of 3DCRT: Conform the prescription dose to the configuration of the target volumes while delivering lower doses to surrounding normal tissues • In 3DCRT, organs at risk can also be delineated to shield these and reduce treatment side effects

TRUE OR FALSE PLANNING CONFORMAL RADIATION THERAPY • The patient usually have a CT/MRI or PET Scan to create a 3D image of the radiotherapy plan that will be based on. • The information from these scans feeds directly into the radiotherapy planning computer. • The treatment team then plan your radiotherapy treatment area in 3 dimensions: -width. - height -depth

• The ____________ designs radiation beams that follow the shape of the tumor very closely. • They make sure that all of the tumor is inside the radiotherapy field • And they avoid as much healthy tissue as possible. • This reduces the risk of side effects.

• The radiographers might make marks on your skin that act as reference points. This is to make sure every treatment session is accurate.

• The _______ or _______ keeps the treatment area completely still. This so your treatment will be as accurate as possible.

SPECIAL TYPES OF CONFORMAL RADIATION THERAPY

• gives radiotherapy from many different angles around the body. • This means the tumor receives a high dose of radiation and the tissues around it receive a much lower dose. - The beams meet at the tumor.

Stereotactic radiotherapy to the brain might be called _________ . This is usually a single treatment. If you have more than one treatment to the brain, this is called stereotactic treatment.

• an advanced form of 3DCRT that uses computer-controlled linear accelerators to deliver precise radiation doses to a malignant tumor or specific areas within the tumor. • IMRT allows for the radiation dose to conform more precisely to the three-dimensional (3-D) shape of the tumor by modulating-or controlling-the intensity of the radiation beam in multiple small volumes.

TYPES OF INTENSITY- MODULATED RADIATION THERAPY (IMRT)

• Is an automated method to deliver an intensity modulated beam at a fixed beam with sequence of MLC segments, in which the radiation is turned on only when the MLC leaves come to step at each proper segment position (step and shoot)

• the MLC leaves are in continuous motion during treatment of each field. • At a fixed beam angle, each pair of opposing MLC leaves is swept across the target volume under computer control to produce the desired profile. • This method does continue to deliver radiation while the MLC is in the beam, producing more leakage and increasing the total body dose.

• The core of IMRT technique is the so called ___________ in which the physician sets ideal dose of targets and normal organs, and relative importance for the tumor and surrounding organs in advance. • Then, the machine computes and determines numbers and angles of the beams.

TRUE OR FALSE FIELD ARRANGEMENT IN EXTERNAL BEAM RADIATION THERAPY • Single Field •Parallel Opposed Field • Multi-field Arrangement • Wedge Field Technique • Moving Field Technique

• Treatment through one _________ arrangement is the simplest treatment and the dose distribution in tissue is essentially as presented on an isodose chart for the particular energy and the field used • With this field arrangement, electron is usually the type of radiation used to treat shallow tumors where a rapid drop in dose beyond the depth of the tumor

• It is a pair of fields directed along the same axis from opposite sides of the treatment volume • Parallel opposed fields are relatively easy to set-up and reproduced from day to day • The 100% isodose line is with in the entire treatment volume

TRUE OR FALSE ADVANTAGES OF PARALLEL OPPOSED FIELD • Simplicity and reproducibility of set-up •Less chance of geometrical miss • Homogenous dose to the tumor

TRUE OR FALSE DISADVANTAGES OF PARALLEL OPPOSED FIELD • Excessive dose to normal tissues critical organs above and below tumors

• The most popular multi-field arrangement is the ____________ which is often used in the treatment of pelvic malignancies.

• The use of _________ directed at the target volume requires that the beam entrance and exit of each field be aimed at different angles/segments, thereby reducing the dose to adjacent tissues • The most popular multi-field arrangement is the "Box Technique" which is often used in the treatment of pelvic malignancies. • The technique consists of opposed anterior and posterior fields and opposed right lateral and left lateral field.

• Wedges are frequently inserted into the beam to alter the shape of the isodose curve • They can be use as compensators to reduce the dose in a region of high dose as a result of the patient shape • 45 degree wedge can be inserted so that the thick part of the wedge is directed at the region of high dose that will result in a uniform dose distribution

• A technique in which the axis of the rotation of the therapy machine, the isocenter, is positioned in the center of the target volume • The radiation source is moved around the patient through a complete circle • It yields a high dose in the target volume where the dose outside this volume falls off rapidly

• Megavoltage electron beams represent an important treatment modality in modern radiotherapy, often providing a unique option in the treatment of superficial tumors ( less than 5 cm deep)

• cones are used to collimate the beam and are attached to the treatment unit head such that the electron field is defined at distances as small as 5 cm from the patient • Several cones are provided usually in square field sizes ranging from 5x5 cm" to 25x 25 cm 2

• (sometimes referred to as "Curietherapy" or"Endocurie Therapy" is a term used to describe the short distance treatment of cancer with radiation from small, encapsulated radionuclide sources • This type of treatment is given by placing sources directly int or near the volume to be treated • Most common brachytherapy sources emit photons, however, in a few specialized situations, beta or neutron emitting sources are used

• dose is delivered over a short period of time and the sources are removed after the prescribed dose has been reached

• dose is delivered over the lifetime of the sourc until complete decay

BRACHYTHERAPY TREATMENTS CLASSIFIED WITH RESPECT TO TREATMENT DURATIONS

BRACHYTHERAPY TREATMENTS CLASSIFIED WITH RESPECT TO SOURCE LOADING

Low Dose Rate (LDR)

Medium Dose Rate (MDR)

High Dose Rate (HDR)

TRUE OR FALSE IMPLANTATION TECHNIQUES • Intracavitary Technique • Interstitial Technique • Mould Therapy or Plesiocurie • Transluminal Brachytherapy

• Consists of positioning applicators containing radioactive sources into a body cavity in close proximity to the target tissue • Eg. Cervix Intracavitary Brachytherapy

• Consists of surgically placing small radioactive sources directly into the target tissue with the used of needles • Hollow stainless steel needles are inserted through the lesion with both ends visible • Plastic tubing with button affixed to the sealed and is threaded throu each needle

• Consist of an applicator containing an array of radioactive sources usually designed to deliver a uniform dose distribution to the skin or mucosal surface

• Consist of inserting a line source into a body lumen to treat it's surface and adjacent tissues

TRUE OR FALSE PHYSICAL STATES OF BRACHYTHERAPY SOURCES • Tubes • Needles • Seeds • Fluids • Opthalmic Applicators.

• are the standard capsules for the radioactive sources used for the treatment of gynecological malignancies • Radium 226, Cobalt 60 and Cesium 137 are normally used isotopes for these tubes • The tube is encapsulated in 0.5 mm platinum that serves as a dual function, one is to prevent tissue and body fluid contact and the other one is to filter beta radiation emitted by Cesium 137 and Alpha particle emitted by Radium 226 • The amount of radioactivity in each tube is usually expressed as milligram radium equivalent (mg Ra eq.)

- Radioactive substances used for interstitial treatment are usually encapsulated in a shield shaped as a needle • These needles are longer than tubes but has small diameter to allow it to penetrate the body or tissue • Indian Club Needles- needles with non-uniform distribution of activity - these needles have greater activity at one end • Dumbbell Needles- have greater activity at both ends and may be used without crossing needles in either end

• These ________ are left in place permanently since their half-life is short • lodine 125 and Gold 198 seeds are routinely left in place permanently while Iridium 192 seeds are removed after a few days when the desired dose has been delivered • The longer half life of Iridium prevents safe permanent implantation • The activity per seed is usually less than 1 mg Ra eq

• The most frequently used radionuclide administered with fluid are Iodine 131 and Phosphorus 32 * These "unsealed" sources are used in the nuclear medicine department

• Some conditions of the conjunctiva, primarily pterygia, is effectively treated with Strontium 90 (Sr-90) source with a half life of 28 years • Beta particles from Yttrium 90- daughter product of Sr-90 are used • This source is encapsulated in a small, semi circular applicator placed directly on the conjunctiva

- Accelerate charged particles - Some are built for basic research in nuclear and high energy physics - Most of them have been modified for radiotherapy

TRUE OR FALSE 2 BASIC CONDITIONS MUST BE MET FOR PARTICLE ACCELERATION: - The particle to be accelerated must be charged - An electric field must be provided in the direction of particle acceleration

TRUE OR FALSE TYPES OF PARTICLE ACCELERATORS • VAN DE GRAAF GENERATOR • MICROTRON • BETATRON • CYCLOTRON LINEAR ACCELERATOR • COBALT-60 UNIT

• This machine was the first particle accelerator that can accelerate electrons up to 2 MV and was developed by R.J. Van de Graaf in 1931 • It is an electrostatic accelerator designed to accelerate charged particles

- Is an electron accelerator which combines the principles of both the linear accelerator and the cyclotron - The electrons are accelerated by the oscillating electric field of a single microwave cavity - As the electron receive higher and higher energy by repeated passes through the cavity, The radius of the orbit in the magnetic field also increases

- Developed by Kertz in 1941 - Is a machine in which the electrons are accelerated inn a circular orbit via a changing magnetic field - The accelerating tube is shaped like a doughnut and is placed between the poles of an alternating current magnet

TRUE OR FALSE BETATRONS WERE FIRST USED FOR RADIATION THERAPY DURING THE 1950'S BUT ARE NOW REPLACED BY LINEAR ACCELERATORS

• was developed by E.O. Lawrence in 1930 for acceleration of ions to a kinetic energy for a few megaelectronvolts. • Initially, the cyclotron was used for basic nuclear physics research; • Later on, found the important medical uses in the production of radioisotopes for nuclear medicine as well as in the production of proton and neutron beams for radiotherapy

machines that produce high electron beams using high- frequency electromagnetic waves to accelerate charged particles in a linear structure • It was first developed by Wideroe in 1928 to accelerate heavy ions like proton • Source-to-axis distance: 100

Five main structures of LINAC

-is the power source of the accelerator -it transforms the alternating current (AC) to direct current (DC) which is needed by the components in the stand

- Contains the klystron which plays a primary role in amplifying the radiofrequency waves for accelerating the electrons - Water used for cooling the pipes and the target are found in the stand

- Contains the treatment head - The treatment head is consist of thick shell of high density shielding material (e.g. lead, tungsten, lead-tungsten alloy) - The treatment head should provide sufficient shielding against leakage radiation - It contains a x-ray target, scattering foil, beam flattening filter ionization chamber, primary and secondary collimators

• "brain" of the accelerator • has the controlling circuit boards and tuning capacitors • used for output and steering adjustment • Daily operation is controlled from the console

•it is where the patient lie during treatment • is not part of the radiation delivery system • main factor in the gantry installation and patient set-up

TRUE OR FALSE OTHER STRUCTURES OF LINAC • MAGNETRON • ELECTRON GUN • WAVE GUIDE • BENDING MAGNET • TARGET • BEAM FLATTENING FILTER • SCATTERING FOIL • IONIZATION CHAMBER • COLLIMATORS - PRIMARY COLLIMATOR - SECONDARY COLLIMATOR • ELECTRON APPLICATOR

• is a device that produces microwaves • the frequency of the microwaves within each pulse is about 300 MHZ • it functions as a high power oscillation generating microwave pulses of several microsecond

• is an electronic device that produces electron to be accelerated and used for radiation therapy and to produce x-rays

• is a vacuum tube that consist of a copper tube with it's interior divides by copper discs or diaphragms of varying aperture and spacing • it is where the electrons are accelerated

• the target of the linear accelerator is transmission-type - because as the kinetic energy of electron increases, the direction of the x-ray emission becomes increasingly forward in which the electrons bombard the target from one side and the x-ray beam is obtained on the other side • it is where the electrons interact to produce x-rays

•place along the path of the x-ray beam in order to attain homogenous intensity of the x-ray beam in the entire field • usually made of tungsten, uranium, steel, aluminum or a combination can be used • used during the x-ray mode of the linear accelerator and removed with the target in placed of scattering foil via a carousel

• used to scattered the pencil thin electron beam • 3 mm in diameter and usually made up of tin • causes a uniform electron distribution within the field

• is a gas filled detector • used to monitor the dose rate, integral dose and field symmetry • controls and switches off the equipment for an adequate radiation to be used

- fixed collimator of LINAC - designed to confine the photon beam or x-ray beam and is essentially a conical opening

• Movable collimator of LINAC • A square aperture that further confines the size of the beam • Consist of two pairs of tungsten blocks (x-jaw and y-jaw) • Provide a rectangular opening from 0 x 0 cm2 to the maximum field size of 40 x 40 cm • Light Localizing System- provided the field size definition • Multi-leaf collimator is used as a secondary collimator in the advancement of technology

• used to restrict the electron beam to a desired field size because the restriction of the primary and secondary collimators are not enough

• The ________source has the shape of a cylinder filled with disks or pellets of isotope with a diameter of 1 to 1.5 cm • The circular end of the cylinder faces the collimator opening grom which the gamma radiation escapes when the machine is in the "on" position • Source Head- housing for the source - consists of a steel shell filled with lead for shielding purposes and a device for bringing the source in front of an opening in the head from which the useful beams emerges

types of simulation

• The purpose of a radiation therapy simulation is to mimic the radiation treatment unit, but instead of a high-energy therapy beam, it produces low-energy, diagnostic quality x-rays for imaging.

• In the mid-1980s, Sherouse and colleagues introduced the term virtual simulation to describe a computer-based simulation process. • They developed a software package that allowed the user to carry out simulation at a computer workstation instead of at a real simulator. • The advantage of this method compared with plain radiographs is that the target volumes and anatomic structures, outlined on the CT scans, are used to make the decision about the position of the isocenter, field sizes, beam directions, and shielding blocks.

May be used to position both arms above the head. This is commonly used with patients with lung and esophageal cancer. Having both arms above the head allows for a better treatment plan to be designed.

Is like a bean bag and consists of a cushion and vacuum compression pump. The patient is placed in the treatment position on a partially inflated cushion. Vac Lok bags are typically used to keep extremities (legs as well as arms) immobilized so that patients are in the same position every day.

used to position the arms and shoulders away from the chest and at the same time elevate the patient on an adjustable-angle board for positioning and daily reproducibility.