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Questions and Answers
What are the two methods used to move the teletherapy source from the BEAM-OFF to the BEAM-ON position?
What are the two methods used to move the teletherapy source from the BEAM-OFF to the BEAM-ON position?
What function does the primary timer serve in the teletherapy machine?
What function does the primary timer serve in the teletherapy machine?
What happens to the beam in the event of a power failure?
What happens to the beam in the event of a power failure?
What is the average permissible leakage radiation from a teletherapy machine head as per international regulations?
What is the average permissible leakage radiation from a teletherapy machine head as per international regulations?
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What additional time should be included in the treatment setting for the teletherapy machine?
What additional time should be included in the treatment setting for the teletherapy machine?
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What material is the source head of the teletherapy machine primarily made from for shielding?
What material is the source head of the teletherapy machine primarily made from for shielding?
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What is the typical amount of head leakage radiation at a distance of 1 meter from the source?
What is the typical amount of head leakage radiation at a distance of 1 meter from the source?
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Which of the following is a feature that appears when the source is in the BEAM-OFF position?
Which of the following is a feature that appears when the source is in the BEAM-OFF position?
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What does the secondary timer act as in the teletherapy machine?
What does the secondary timer act as in the teletherapy machine?
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What component of the teletherapy machine is responsible for creating the clinical gamma ray beam?
What component of the teletherapy machine is responsible for creating the clinical gamma ray beam?
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Which safety feature is incorporated into both methods for moving the teletherapy source?
Which safety feature is incorporated into both methods for moving the teletherapy source?
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What applies to leakage radiation from the teletherapy machine when the source is in the BEAM-OFF position?
What applies to leakage radiation from the teletherapy machine when the source is in the BEAM-OFF position?
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What is the primary purpose of the secondary timer in the teletherapy machine?
What is the primary purpose of the secondary timer in the teletherapy machine?
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During treatment with teletherapy machines, what is included in the set treatment time?
During treatment with teletherapy machines, what is included in the set treatment time?
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Which of the following describes the head of a cobalt-60 teletherapy machine?
Which of the following describes the head of a cobalt-60 teletherapy machine?
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What characteristic is true about the source moving mechanisms in cobalt-60 teletherapy machines?
What characteristic is true about the source moving mechanisms in cobalt-60 teletherapy machines?
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How does optical visualization of the radiation field occur in a cobalt-60 teletherapy machine?
How does optical visualization of the radiation field occur in a cobalt-60 teletherapy machine?
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Which of these statements about the motion of the teletherapy source is most accurate?
Which of these statements about the motion of the teletherapy source is most accurate?
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Which of the following is a key function of the primary timer in the teletherapy machine?
Which of the following is a key function of the primary timer in the teletherapy machine?
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What should be the average leakage radiation from a teletherapy machine head according to regulations?
What should be the average leakage radiation from a teletherapy machine head according to regulations?
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Study Notes
Cobalt-60 Teletherapy Machine
- The source head is constructed with a steel shell incorporating lead for effective radiation shielding.
- Mechanism utilized to position the radiation source in front of the collimator to generate the gamma ray beam.
Source Movement Methods
- Two primary methods for transitioning the teletherapy source from BEAM-OFF to BEAM-ON:
- Sliding drawer mechanism.
- Rotating cylinder mechanism.
Safety Features
- Both source movement methods include an automatic beam termination feature during power failures or emergencies.
- Optical visualization is provided when the source is in the BEAM-ON position, indicated by a light source above the collimator opening.
Leakage Radiation
- Leakage radiation can occur even when the source is in the BEAM-OFF position.
- Head leakage typically measures less than 1 mR/h (0.01 mSv/h) at a distance of 1 meter from the source.
- International safety standards mandate that average leakage from a teletherapy machine head remains below 2 mR/h (0.02 mSv/h).
Dose Delivery Mechanism
- Treatment dose delivery is regulated by two timers: primary and secondary.
- The primary timer controls the beam time and switches it off after the prescribed duration.
- The secondary timer functions as a backup to ensure the beam is turned off if the primary timer fails.
- Treatment time must factor in shutter correction time, accounting for the source's travel time between BEAM-OFF and BEAM-ON positions.
Cobalt-60 Teletherapy Machine
- The source head is constructed with a steel shell incorporating lead for effective radiation shielding.
- Mechanism utilized to position the radiation source in front of the collimator to generate the gamma ray beam.
Source Movement Methods
- Two primary methods for transitioning the teletherapy source from BEAM-OFF to BEAM-ON:
- Sliding drawer mechanism.
- Rotating cylinder mechanism.
Safety Features
- Both source movement methods include an automatic beam termination feature during power failures or emergencies.
- Optical visualization is provided when the source is in the BEAM-ON position, indicated by a light source above the collimator opening.
Leakage Radiation
- Leakage radiation can occur even when the source is in the BEAM-OFF position.
- Head leakage typically measures less than 1 mR/h (0.01 mSv/h) at a distance of 1 meter from the source.
- International safety standards mandate that average leakage from a teletherapy machine head remains below 2 mR/h (0.02 mSv/h).
Dose Delivery Mechanism
- Treatment dose delivery is regulated by two timers: primary and secondary.
- The primary timer controls the beam time and switches it off after the prescribed duration.
- The secondary timer functions as a backup to ensure the beam is turned off if the primary timer fails.
- Treatment time must factor in shutter correction time, accounting for the source's travel time between BEAM-OFF and BEAM-ON positions.
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Description
This quiz explores the components and mechanisms of the Cobalt-60 teletherapy machine used in cancer treatment. It covers the structure of the source head, including shielding and the methods for moving the source between BEAM-OFF and BEAM-ON positions. Perfect for students in Medical Physics.
