radthera

Shanks Redhaired · 7問 · 1年前

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Types of brachytherapy Depends on

Duration of implant Source position Source loading pattern Dose rate

Brachytherapy treatment classified with respect to treatment duration

Temporary Implant Permanent Implant

Dose is delivered over a short period of time and the sources

temporary

It may be LDR or HDR.

temporary

The specific treatment duration will depend on many different factors, including the required rate of dose delivery and the type, size and location of the cancer.

temporary

Isotopes in temporary

Cesium 137 Iridium 192

Dose is delivered over a lifetime of the source until complete decay.

permanent

Permanent implantation

seed implantation

Placing small LDR radioactive seeds (about the size of a grain of rice) in the tumor or treatment site and leaving them there permanently to a gradually decay.

permanent

Isotopes in permanent

Iodine 125 Palladium 103 Gold 198

Source Position

interstitial contact

the sources are placed directly in the target tissue of the affected site, such as the prostate or breast.

interstitial

involves placement of the radiation source in a space next to the target tissue.

contact

The applicator is preloaded and contains radioactive sources at the time of placement into the patient.

hot loading

Who developed remote controlled trolley

cyril jayachandran

The applicator is placed first into the target position and the radioactive sources are loaded later

afterloading

Ir192 wires, sources manipulated into applicator by means of forceps & hand-held tools

manual afterloading

consists of pneumatically or motor-driven source transport system

remote afterloading

The use of remote afterloading devices offers several practical advantages over manual procedures, such as

Increased patient treatment capacity; Consistent and reproducible treatment delivery; Reduced radiation exposure of staff

Remote afterloading devices are used in both WHAT clinical applications. The anatomic sites commonly treated with these devices are similar to those treated with conventional brachytherapy procedures

interstitial and intracavitary

are used in both interstitial and intracavitary clinical applications. The anatomic sites commonly treated with these devices are similar to those treated with conventional brachytherapy procedures

remote after loading

The three commonly used radioactive sources in remote afterloading devices are

60Co, 137Cs and 192Ir.

Currently the most commonly used source for afterloading is

ir192

Implantation Technique

Inracavitary Interstitial Mould therapy Transluminal

Emit radiation at a rate of 0.4–2 Gy/hour.

LDR

LDR dose rate

0.4–2 Gy/hour.

characterized by a medium rate of dose delivery, ranging between 2-12 Gy/hour.

MDR

Dose rate MDR

2-12 Gy/hour.

when the rate of dose delivery exceeds 12 Gy/h.

HDR

HDR dose rate

exceeds 12 Gy/h.

involves short pulses of radiation, typically once an hour, to simulate the overall rate and effectiveness of LDR treatment.

PDR

Dose range 0.03 to 0.3 Gy/Hr

ULDR

ULDR dpse rate

0.03-0.3 gy/h

The advantages of using HDR systems over LDR systems are:

optimization of dose distribution; outpatient treatments; and elimination of staff radiation exposure.

ADVANTAGES USING PULSED-DOSE RATE

The patient is not irradiated for most of each hour. The computer control the source. It is easy to correct for natural source decay.

Fletcher suit system

Tandem Ovoid Keel

Cylinders

Burnett Cylinder

is mostly used for cancers of the uterine cervix, uterine body and vagina. Various applicators are in use to hold the sources in an appropriate configuration

intracavitary

Consists of surgically placing small radioactive sources directly into the target tissue with the use of needles.

interstitial

Hollow stainless steel needles are inserted through the lesion with both ends visible, plastic tubing with button affixed through each needle.

interstitial

most widely used source for the treatment of gynaecological cancers is

cs137

It is often necessary to use sources of different strengths in order to achieve the desired dose distribution.

interstitial

Consist of applicator array of radioactive sources usually designed to deliver a uniform dose distribution to the skin of mucosal surface.

mould therapy

Lumen of the tissue

translimal brachytherapy

Physical states of brachytherapy source

Tubes Needles Seeds Fluids Ophthalmic Applicators

Are standard capsules for the radioactive source used for the treatment of gynecological malignancies.

tubes

Tube are standard capsules for the radioactive source used for the treatment of WHAT?

gynecological malignancies

Encapsulated with platinum.

tube

Tube isotopes

Radium-226 Cobalt 60 Cesium-137

Radioactive substance use for interstitial treatment are usually encapsulated in a shield shape

needles

Longer than tubes but small in diameter

needles

are left in placed permanently.

seeds

Isotopes in seeds

Iodine-125 and gold 198 Iridium 192

Fuild isotopes

Iodine 131 and phosphorus 32

Decays alpha emission and part of a long decay chain with natural Uranium and concludes in an isotopes of stable lead

Ra226

was very practical because it has a very high specific activity.

radium 226

Specific activity is the activity per unit mass of radioactive material. It dictates the total activity that a small source can have.

radium 226

One of the most widely used of the radium substitutes and has largely replaced radium as the primary isotope for brachytherapy of the uterus and cervix.

cesium 137

It reduces the radiation safety hazard.

cesium 137

Less problematic when it comes to storing compared with radium.

cesium 137

sources in a wide variety of needle or tube configurations.

cesium 137

Supplied in form of wires of this – platinum alloy or a small seeds of this alloy attached to the nylon ribbon with spacing of 1 cm between seeds.

ir192

Undergoes beta decay and has average energy of 380 KeV

ir192

They were being inserted into the tissue carrier needles that penetrate through the tumor or around the tumor.

iridium 192

They are not commonly used in brachytherapy applications.

co60

Undergoes a two tiered beta decay after its neutron activation that produces 1.117 and 1.33 MeV gamma rays which averaged of 1.25 MeV.

co60

It has been used for ophthalmic applicators in some application in some needles and tubes.

co60

Popular replacement for radium – 222 in permanent implants.

au198

Radiation safety is less problem and more dose is absorbed locally.

au198

They are formed in a cylinder grains or seeds.

au198

They have an activity of approximately 5 mCi/seeed.

au198

gives tissue a very high dose rate in a short time, a method called high-dose rate therapy.

au198

Becoming more common in interstitial seed plants.

I125

Making iodine therapy a low dose rate therapy.

I125

Dosage System

Paris System Paterson-Parker (Manchester) Quimby

calculated and tabulated dose distributions for linear radium sources with different active lengths and wall thickness.

quimby

The tabulated data give the centigrays per hour at locations along as well as away from the axis of 1 mg –radium radium source.

quimby

Manchester system

Paterson parker

Establishes a set of guidelines that, if followed, will provide dose of 10% within the implanted area.

Paterson parker

devised to deliver a reasonably uniform dose to a plane or volume.

Paterson parker

The system assumes the use of linear sources to be implanted in tissue in planes or other geometric shapes and gives rules for placing the radium sources in this case.

Paterson parker

The sources are distributed non-uniformly following certain rules, based on the size of the target volume, with more source strength concentrated in the periphery. Usually the prescribed dose is about 10% higher than the minimum dose within the treated volume.

Paterson parker

The source arrangement treats a slab of tissue 1 cm thick. The prescribed dose is on a parallel plane, 0.5 cm away from the source plane.

single plane

Thicker slabs of tissue, usually up to about 2.5 cm, are treated with sources placed in two parallel planes. The required total source strength is equally divided between the two planes, following the distribution rules for single plane implants

double plane

The planes should be 1 cm apart and parallel

planar implants

Square and rectangle implants The planes should be 1 cm apart and parallel.

planar implants

If the shape of the implanted volume resembles a three dimensional shape more than a plane.

volume implants

Cylinders, ellipsoids, spheres and cubes.

volume implants

This type of calculations are done for seed implants of the prostate and other implants

volume implants

Utilizes uniform distribution of the radioactivity and the rules can be applied to volumes of any shape

paris

Aid in treatment setup and reproducibility.

immobilization device

Support the conditions prescribe in the treatment plan

immobilization device

Devices designed to place the patient in particular position for treatment. Restrict the movement of the patient during treatment.

immobilization device

are individualized immobilizers that restrict patient movement and ensure reproducibility in positioning.

complex immobilization device

Immobilization devices

Masking tape or paper tape. Plastic or cloth straps with Velcro. Rubber bands Head frame with bite block. Plaster cast Foaming agents Alpha cradle Vac-Lok Thermoplastic molds

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