M4 Explain The Principles And Effects Of Radiation Therapy And The Equipment Used
Assignment Front sheet
BTEC National Extended Diploma in Applied Science
Unit: 20
Medical Physics Techniques
Assignment Number:4
Radiotherapy & Radiation Protection
Subject /Unit Teacher:
Adrian Greaves
Tutor & Tutor Group
Student Name:
KamenStanchev
Feedback Date(s):
Date Received:
Final Hand-in Date:
Student declaration : I declare that the work submitted is my own and has not been lent to anybody else or copied from them; that all internet and other references have been acknowledged. or Signed …………………. ……………………. Date …………….
Final Submission
Grading
Criteria
Task
Number
Outcomes Assessed
Grading Criteria Achieved
P6
Explain the principles and effects of radiation therapy and the equipment used.
M4
Explain …show more content…
how excessive exposure to radiation can cause harm.
D4
Evaluate a range of therapy techniques, types of radiation available and the equipment used.
Functional skills Literacy Level 2
MET
Speaking and listening presenting the result of research into chosen areas
Reading researching chosen industrial applications from a wide range of sources
Writing writing reports
Teacher signature:
Date:
Sampled for Internal Verification: Y/N (see separate sheet)
(this should form the back of the first sheet)
Student Comments:
Date:
Teacher/Assessor comment:
Date:
Internal Verifier feedback to Assessor
Date:
BTEC National Extended Diploma Applied Science
Unit 20 Medical Physics Techniques
Assignment 4 Radiotherapy and Radiation Protection
1. Use this diagram to explain how a LINAC works:
Electron gun is emitting electron beam through thermionic emissionjust the same as the X-ray tube.
The electrons are accelerated to a speed close to the light along with an evacuated tube and in order to generate an X-ray beam, the electrons are being deflected as a general rule to 90o via electromagnets to hit the target. The electrons quickly reduce their speed, giving up their energies to high-energy X-radiation because the electron energies involved are so greater compared to X-ray tube. A transmission target is used whereby X-rays are being produced from the long side of the target and directed into the patient. A computer-controlled gantry and treatment couch ensure any treatment position, whereas a dose monitor is used to measure the cumulative dose and to cut off the device at the appropriate …show more content…
time.
b) Give two differences between this machine and the cobalt 60 machine.
Instead of using high-energy X-ray beams cobalt-60 machine uses y-rays from a radioactive source that could be directed as well as LINAC into a patient to treat a cancer.
A great care should be taken to protect the high-activity cobalt source of all time because it decays spontaneously and cannot be switched off compared to LINAC.
c) Look at the following photographs of two types of brachytherapy. Explain the main features of each type including the type of treatment and the possible sources used.
Cervical brachytherapy
Prostate brachytherapy
Cervical brachytherapy is produced by specially made hollow tubes called "applicators" that are inserted inside the womb or vagina.
During the treatment, a machine is used to place the radioactive material inside the applicator and once the treatment is over the machine takes back radioactive material and the applicators is removed. The brachytherapy could be given into two different treatments(high or low dose rate treatment). With the bothtreatments a same dose of radiotherapy is given, whereas for over a different time. High dose rate treatment is given for a short period of time, whereas low dose are given for longer period of time.
Small radioactive seeds of Iodine-125 could be inserted where the tumor is located and they are left inside to release their radioactivity slowly. This process sometimes is known as low-dose rate treatment. The seeds are not removed from the patient and eventually fades away for the time of six months. All of the radioactivity is absorbed by the prostate so therefore it's safe for the patient to stay next to other
people.
A second option for prostate brachytherapy is that the seeds are being placed in specific catheters, which have been inserted inside the prostate gland while the patient was sleeping in the operating theatre. The seeds are put in a specific period of time and then are removed and this process is known as high-dose rate treatment. Once the treatment is over, the catheters are removed and there is no track of radioactive material inside the prostate gland. P4
2) You are asked to explain the benefits and risks attached to the various uses of radiation in a hospital.
a) Draw a flow chart showing the chain of events which can take place when living tissue is exposed to ionising radiation. Ensure that your chart includes direct and indirect action, deterministic and stochastic effects.
b) Fill out the following table:
Radiation Effect
Definition
Example
Somatic
It is biological effect that does not affect the gonads so therefore they are not transmitted to the offspring.
An example of somatic effect would be radiation sickness.
Genetic
Genetic effect is suffered by the offspring of the single exposed. Small dose of ionizing radiation could permanentlydamage the DNA in germ cells.
c) Use the information in the table to answer the following questions:
i) What is the source of the radiation you are exposed to on a flight?
The exposure of radiation on a flight that the aircrew and passengers is 2 mSv.
ii) Why is this higher than when you are on the ground?
It is higher than the ground because of the cosmic rays. Most of the cosmic rays on the ground are being absorbed by the atmosphere, whereaswhen is higher than on the ground the absorption of these rays is lower.
d) The following questions are about doses received from CT (computerised tomography) scans.
Examination
Typical equivalent dose (mSv) chest CT
5.8
whole torso (chest, abdomen, pelvis) CT
9.9
i) How many whole torso CT scans would produce a dose that causes immediate radiation sickness? (equivalent dose which causes immediate radiation sickness is 1000mSv)
1000÷9.9= 101.01 so therefore approximately 101 typical whole torso CT are needed to causes immediate radiation sickness.
ii) How many chest X-rays would have the same effect as a dose that causes immediate radiation sickness?
1000÷5.8=172.41 so therefore approximately 172.41 typical chest CT are needed to cause immediate radiation sickness,
e) During radiation testing a health worker is exposed to 10µGy of α radiation with quality factor of 20 and 25µGy of γ rays (qf=1). Calculate the total equivalent dose for these radiations.
α radiation x quality factor--> 10 x 20 = 200µGy
Total equivalent dose= 200+25= 225 µGy
M4
3) What are the two main advantages of megavoltage therapy over superficial therapy?
It decreases the damage sustained by the patient's skin.
It reduces the damage to the bones.
b) Use the diagram below to describe in detail how gamma radiation from a radioactive source is used to treat a tumour in a cancer patient while doing the minimum damage to healthy tissue.
For treating tumors deep within the body, higher-energy X-ray photons are required because lower-energy photons are more easily absorbed by the soft tissue. They do not reach deep enough into the body and could cause damage to the tissues that absorb them. Therefore, to do the minimum damage to healthy tissues, different type of beams are used. X-ray are delivered by different beams that meet on the side of the malignant cells and by this way the harm of the surrounding tissue is being reduced. Multiple beam therapy gives short doses of radiation at each of the number of the positions as the diagram shows above 1, 2 and 3 and only the tumor receives the dose each time. By rotating the patient around the axis of the tumor the same effect could be obtained. Another way to do this process is by using a single beam while rotating the patient around and always aiming the beam towards the tumor.
c) What method do you think would be used to ensure that the beam is focused directly onto the tumor? You should consider what needs to be done to keep the patient in one place and how the beam of radiation is precisely focused onto the patient.
In order to minimize the damages inthe patient's body and ensure that the beam is focused directly onto the tumor, a number of low-intensity beams are directed into the patient from different locations. If all the different low-intensity beams combine at the tumor, the dose that would be produced could be enough to destroy the cancer cells while not damaging healthy tissues around it. This process could be performed by using the multiple and rotational beams, which I have already explained in the previous question.
Usually patient lie down on a couch and radiation machines are positioned above the patient. The therapist may adjust the patient position, the angle and the position of the machine which means that when the machine emits radiation the rays would be focused on the exact part of the body that they want. Lead shields could be placed over certain areas of the body of the patient to protect them from the radiation.
Once the patient is being settled inside the machine, the therapist has to leave and go to separate control room. This is done for their own protection from repeated exposure to radiation, whereas in the control room they still see and talk to the patient.
d) Brachytherapy implants a tiny amount of a radioactive material directly into a tumour where it remains for several days.
i) The radioisotope iridium-192 often used emits beta particles and low energy gamma rays. Why would this source not be suitable for external beam therapy?
Iridium-192 is not a suitable source for external beam therapy because it emits beta particles and low energy gamma rays. In external beam therapy therapist want to destroycancer cell,prevent the cancer from coming back and help other cancer treatment work better. Since, Iridium-192 emits beta particles that are less ionizing and more dangerous compared to gamma rays because they are not able to travel to far away inside the body and the soft tissues would absorb them. This would cause many hazardous effects such as damaging of the cells and DNA molecules that could lead to several cell changes known as mutations.
ii) Why is it suitable for brachtherapy?
Iridium-192 is suitable for brachtherapy because it is a radionuclide with high specific activity, which means that a very small source could provide a very high dose rate. The effective photon energy of around 350 keVis ensuring enough absorption dose at a good distance from the source to the treatment target.
iii) What is the main advantage of brachytherapy over external beam therapy?
In brachytherapy, the radiation is precisely delivered within the body, reducing the risk of unnecessary damages to healthy tissues and organs close to the tumor, whereas in external beam therapy, the radiation has to travel through healthy tissues and organs to reach the tumor. Therefore more healthy tissues and organs would be exposed to the radiation and that's why brachytherapy is better compared to external beam therapy.D4
Corrections
Task 1 (c)
There are two main types of brachytherapy; Intracavitary radiation and interstitial radiation. Both of the methods are using radioactive implants such as seeds, wires, needles, capsules or tubes.
Intracavitary brachytherapy- The radioactive source, which is called implant, are put into a space next to the tumour where is actually located. This space may be a body cavity such as the cervix, uterus or vagina.
Interstitial brachytherapy- the radioactive source, which is called implant, are put directly into the tissue or near to the affected site, whereas not in body a cavity, such as the prostate or breast.
Task 2 b)
An example of genetic effects is that the affected cells are the reproductive cells such as the egg and sperm cells.
Task 3 (c)
Before a any treatments to begin, the specific area that must be target is identified by using a special x-ray machine known as a stimulator. This machine has a rotating gantry almost the same as the treatment machine whereas instead is fitted with diagnostic X-ray system and an image intensifier.
Also the radiation therapist could mark the treatment area on the body of the patient with non-permanent ink. These methods are done because it helps the technicians to line up the radiotherapy equipment correctly. Once locating the perfect position for the treatment, the radiation therapist may mart certain points of patient's body with a tiny permanent skin mark to make sure that any further treatment are accurately deliver.
BTEC National Extended Diploma in Applied Science
Unit: 20
Medical Physics Techniques
Assignment Number:4
Radiotherapy & Radiation Protection
Subject /Unit Teacher:
Adrian Greaves
Tutor & Tutor Group
Student Name:
KamenStanchev
Feedback Date(s):
Date Received:
Final Hand-in Date:
Student declaration : I declare that the work submitted is my own and has not been lent to anybody else or copied from them; that all internet and other references have been acknowledged. or Signed …………………. ……………………. Date …………….
Final Submission
Grading
Criteria
Task
Number
Outcomes Assessed
Grading Criteria Achieved
P6
Explain the principles and effects of radiation therapy and the equipment used.
M4
Explain …show more content…
how excessive exposure to radiation can cause harm.
D4
Evaluate a range of therapy techniques, types of radiation available and the equipment used.
Functional skills Literacy Level 2
MET
Speaking and listening presenting the result of research into chosen areas
Reading researching chosen industrial applications from a wide range of sources
Writing writing reports
Teacher signature:
Date:
Sampled for Internal Verification: Y/N (see separate sheet)
(this should form the back of the first sheet)
Student Comments:
Date:
Teacher/Assessor comment:
Date:
Internal Verifier feedback to Assessor
Date:
BTEC National Extended Diploma Applied Science
Unit 20 Medical Physics Techniques
Assignment 4 Radiotherapy and Radiation Protection
1. Use this diagram to explain how a LINAC works:
Electron gun is emitting electron beam through thermionic emissionjust the same as the X-ray tube.
The electrons are accelerated to a speed close to the light along with an evacuated tube and in order to generate an X-ray beam, the electrons are being deflected as a general rule to 90o via electromagnets to hit the target. The electrons quickly reduce their speed, giving up their energies to high-energy X-radiation because the electron energies involved are so greater compared to X-ray tube. A transmission target is used whereby X-rays are being produced from the long side of the target and directed into the patient. A computer-controlled gantry and treatment couch ensure any treatment position, whereas a dose monitor is used to measure the cumulative dose and to cut off the device at the appropriate …show more content…
time.
b) Give two differences between this machine and the cobalt 60 machine.
Instead of using high-energy X-ray beams cobalt-60 machine uses y-rays from a radioactive source that could be directed as well as LINAC into a patient to treat a cancer.
A great care should be taken to protect the high-activity cobalt source of all time because it decays spontaneously and cannot be switched off compared to LINAC.
c) Look at the following photographs of two types of brachytherapy. Explain the main features of each type including the type of treatment and the possible sources used.
Cervical brachytherapy
Prostate brachytherapy
Cervical brachytherapy is produced by specially made hollow tubes called "applicators" that are inserted inside the womb or vagina.
During the treatment, a machine is used to place the radioactive material inside the applicator and once the treatment is over the machine takes back radioactive material and the applicators is removed. The brachytherapy could be given into two different treatments(high or low dose rate treatment). With the bothtreatments a same dose of radiotherapy is given, whereas for over a different time. High dose rate treatment is given for a short period of time, whereas low dose are given for longer period of time.
Small radioactive seeds of Iodine-125 could be inserted where the tumor is located and they are left inside to release their radioactivity slowly. This process sometimes is known as low-dose rate treatment. The seeds are not removed from the patient and eventually fades away for the time of six months. All of the radioactivity is absorbed by the prostate so therefore it's safe for the patient to stay next to other
people.
A second option for prostate brachytherapy is that the seeds are being placed in specific catheters, which have been inserted inside the prostate gland while the patient was sleeping in the operating theatre. The seeds are put in a specific period of time and then are removed and this process is known as high-dose rate treatment. Once the treatment is over, the catheters are removed and there is no track of radioactive material inside the prostate gland. P4
2) You are asked to explain the benefits and risks attached to the various uses of radiation in a hospital.
a) Draw a flow chart showing the chain of events which can take place when living tissue is exposed to ionising radiation. Ensure that your chart includes direct and indirect action, deterministic and stochastic effects.
b) Fill out the following table:
Radiation Effect
Definition
Example
Somatic
It is biological effect that does not affect the gonads so therefore they are not transmitted to the offspring.
An example of somatic effect would be radiation sickness.
Genetic
Genetic effect is suffered by the offspring of the single exposed. Small dose of ionizing radiation could permanentlydamage the DNA in germ cells.
c) Use the information in the table to answer the following questions:
i) What is the source of the radiation you are exposed to on a flight?
The exposure of radiation on a flight that the aircrew and passengers is 2 mSv.
ii) Why is this higher than when you are on the ground?
It is higher than the ground because of the cosmic rays. Most of the cosmic rays on the ground are being absorbed by the atmosphere, whereaswhen is higher than on the ground the absorption of these rays is lower.
d) The following questions are about doses received from CT (computerised tomography) scans.
Examination
Typical equivalent dose (mSv) chest CT
5.8
whole torso (chest, abdomen, pelvis) CT
9.9
i) How many whole torso CT scans would produce a dose that causes immediate radiation sickness? (equivalent dose which causes immediate radiation sickness is 1000mSv)
1000÷9.9= 101.01 so therefore approximately 101 typical whole torso CT are needed to causes immediate radiation sickness.
ii) How many chest X-rays would have the same effect as a dose that causes immediate radiation sickness?
1000÷5.8=172.41 so therefore approximately 172.41 typical chest CT are needed to cause immediate radiation sickness,
e) During radiation testing a health worker is exposed to 10µGy of α radiation with quality factor of 20 and 25µGy of γ rays (qf=1). Calculate the total equivalent dose for these radiations.
α radiation x quality factor--> 10 x 20 = 200µGy
Total equivalent dose= 200+25= 225 µGy
M4
3) What are the two main advantages of megavoltage therapy over superficial therapy?
It decreases the damage sustained by the patient's skin.
It reduces the damage to the bones.
b) Use the diagram below to describe in detail how gamma radiation from a radioactive source is used to treat a tumour in a cancer patient while doing the minimum damage to healthy tissue.
For treating tumors deep within the body, higher-energy X-ray photons are required because lower-energy photons are more easily absorbed by the soft tissue. They do not reach deep enough into the body and could cause damage to the tissues that absorb them. Therefore, to do the minimum damage to healthy tissues, different type of beams are used. X-ray are delivered by different beams that meet on the side of the malignant cells and by this way the harm of the surrounding tissue is being reduced. Multiple beam therapy gives short doses of radiation at each of the number of the positions as the diagram shows above 1, 2 and 3 and only the tumor receives the dose each time. By rotating the patient around the axis of the tumor the same effect could be obtained. Another way to do this process is by using a single beam while rotating the patient around and always aiming the beam towards the tumor.
c) What method do you think would be used to ensure that the beam is focused directly onto the tumor? You should consider what needs to be done to keep the patient in one place and how the beam of radiation is precisely focused onto the patient.
In order to minimize the damages inthe patient's body and ensure that the beam is focused directly onto the tumor, a number of low-intensity beams are directed into the patient from different locations. If all the different low-intensity beams combine at the tumor, the dose that would be produced could be enough to destroy the cancer cells while not damaging healthy tissues around it. This process could be performed by using the multiple and rotational beams, which I have already explained in the previous question.
Usually patient lie down on a couch and radiation machines are positioned above the patient. The therapist may adjust the patient position, the angle and the position of the machine which means that when the machine emits radiation the rays would be focused on the exact part of the body that they want. Lead shields could be placed over certain areas of the body of the patient to protect them from the radiation.
Once the patient is being settled inside the machine, the therapist has to leave and go to separate control room. This is done for their own protection from repeated exposure to radiation, whereas in the control room they still see and talk to the patient.
d) Brachytherapy implants a tiny amount of a radioactive material directly into a tumour where it remains for several days.
i) The radioisotope iridium-192 often used emits beta particles and low energy gamma rays. Why would this source not be suitable for external beam therapy?
Iridium-192 is not a suitable source for external beam therapy because it emits beta particles and low energy gamma rays. In external beam therapy therapist want to destroycancer cell,prevent the cancer from coming back and help other cancer treatment work better. Since, Iridium-192 emits beta particles that are less ionizing and more dangerous compared to gamma rays because they are not able to travel to far away inside the body and the soft tissues would absorb them. This would cause many hazardous effects such as damaging of the cells and DNA molecules that could lead to several cell changes known as mutations.
ii) Why is it suitable for brachtherapy?
Iridium-192 is suitable for brachtherapy because it is a radionuclide with high specific activity, which means that a very small source could provide a very high dose rate. The effective photon energy of around 350 keVis ensuring enough absorption dose at a good distance from the source to the treatment target.
iii) What is the main advantage of brachytherapy over external beam therapy?
In brachytherapy, the radiation is precisely delivered within the body, reducing the risk of unnecessary damages to healthy tissues and organs close to the tumor, whereas in external beam therapy, the radiation has to travel through healthy tissues and organs to reach the tumor. Therefore more healthy tissues and organs would be exposed to the radiation and that's why brachytherapy is better compared to external beam therapy.D4
Corrections
Task 1 (c)
There are two main types of brachytherapy; Intracavitary radiation and interstitial radiation. Both of the methods are using radioactive implants such as seeds, wires, needles, capsules or tubes.
Intracavitary brachytherapy- The radioactive source, which is called implant, are put into a space next to the tumour where is actually located. This space may be a body cavity such as the cervix, uterus or vagina.
Interstitial brachytherapy- the radioactive source, which is called implant, are put directly into the tissue or near to the affected site, whereas not in body a cavity, such as the prostate or breast.
Task 2 b)
An example of genetic effects is that the affected cells are the reproductive cells such as the egg and sperm cells.
Task 3 (c)
Before a any treatments to begin, the specific area that must be target is identified by using a special x-ray machine known as a stimulator. This machine has a rotating gantry almost the same as the treatment machine whereas instead is fitted with diagnostic X-ray system and an image intensifier.
Also the radiation therapist could mark the treatment area on the body of the patient with non-permanent ink. These methods are done because it helps the technicians to line up the radiotherapy equipment correctly. Once locating the perfect position for the treatment, the radiation therapist may mart certain points of patient's body with a tiny permanent skin mark to make sure that any further treatment are accurately deliver.