Radiotherapy

• What is the primary use of radiotherapy?

  Treating cancer with high energy X-rays
• Why do cancerous cells respond better to X-rays than healthy cells?

  Cancerous cells divide more frequently
• What is the effect of X-rays on cancer cells compared to healthy cells?

  X-rays destroy cancer cells at a greater rate
• What type of X-rays are used for treating skin cancer?

  Lower-energy X-rays
• What type of X-rays are used for targeting deeper tumors?

  Higher energy X-rays
• What are the two types of external treatment using X-rays?

  • External treatment using low-energy X-rays
  • External treatment using high-energy X-rays
• How do low-energy X-rays treat skin cancer?

  They are directed at surface tumors
• What is the benefit of using low-energy X-rays?

  Reduced risk of damage to deeper tissues
• What is external beam radiotherapy (EBRT)?

  Directing high-energy X-rays at deep tumors
• Why are cells sensitive to X-ray radiation during division?

  They are actively dividing and vulnerable
• How does EBRT minimize exposure to healthy cells?

  By using metal filters and directing X-rays
• What is the purpose of using metal filters in EBRT?

  To remove low-energy X-rays
• How does the patient remain still during EBRT?

  They are held in a made-to-fit mould
• What is the effect of filtering the beam through an aluminium sheet?

  Removes less energetic X-rays
• Why is it important that only more energetic X-rays reach the tumor?

  To avoid damaging healthy tissue
• What is conformal radiotherapy?

  Shaping the X-ray beam to match the tumor
• How are X-rays produced in a linear accelerator (LINAC)?

  By accelerating electrons towards a heavy metal target
• What is the advantage of rotating the LINAC source around the patient?

  It delivers a larger dose to the tumor
• What is internal radiotherapy?

  • Placement of a radioactive implant next to or into the tumor
  • Uses metal 'seeds' containing radioisotopes
  • Irradiates the tumor and surrounding tissue
• What is the main advantage of internal radiotherapy?

  Source of radiation is close to cancer
• What is the main disadvantage of internal radiotherapy?

  Exposure of healthy tissue to radiation
• What characteristics should a radioisotope have for implants?

  Short half-life, short range, highly ionising
• Why is beta radiation commonly used in implants?

  It penetrates the seed's casing but not far
• Why is alpha radiation not suitable for internal radiotherapy?

  It cannot penetrate the metal casing of seeds
• What happens if alpha particles could penetrate the seeds?

  They would harm healthy tissue instead
• Why is EBRT more appropriate for brain tumors than radioactive implants?

  • Radioactive implants are difficult to place in the skull
  • EBRT localizes the largest dose to the tumor
  • No surgery is required for EBRT
• Why are multiple methods for cancer treatment necessary?

  • Cancer can appear in various body parts
  • Different methods work better for different situations
  • Knowledge of each method is essential for exams