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Clinical Oncology & Treatment Techniques Flashcards

6 cards from real CMD practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 6 Clinical Oncology & Treatment Techniques flashcards as text

  1. The dose-volume histogram (DVH) type that shows the percentage of a structure volume receiving at least a given dose is called:

    Answer: Cumulative (integral) DVH

    The cumulative DVH plots the fractional volume of a structure receiving at least a specified dose and is the standard format for evaluating treatment plans against dose-volume constraints.

  2. Which organ at risk constraint is commonly applied for the spinal cord in radical radiation therapy to prevent radiation myelopathy?

    Answer: Maximum point dose ≤ 45–50 Gy in conventional fractionation

    The spinal cord maximum dose is typically limited to 45–50 Gy in conventional fractionation to maintain the risk of radiation myelopathy below 0.2%.

  3. In prostate cancer treatment planning, which normal tissue constraint is used to reduce the risk of rectal bleeding?

    Answer: Rectal V70 < 20% (volume of rectum receiving 70 Gy)

    Limiting the rectal V70 to less than 20% reduces the risk of late rectal toxicity, including rectal bleeding, following definitive prostate radiotherapy.

  4. The electron beam depth dose characteristic known as the 'practical range' (Rp) is used to:

    Answer: Estimate the maximum depth of electron beam penetration in tissue

    The practical range Rp represents the depth beyond which the electron dose falls to near zero and is used to select appropriate electron beam energy for target coverage.

  5. Which beam arrangement is used in total body irradiation (TBI) to achieve dose uniformity across the entire patient?

    Answer: Bilateral extended-SSD fields with compensators or lung blocks

    TBI uses extended SSD bilateral fields with tissue compensators and partial lung blocks to achieve ±10% dose homogeneity across the heterogeneous patient anatomy.

  6. In brachytherapy, HDR (High Dose Rate) is defined as a dose rate greater than:

    Answer: 12 Gy/hour

    Per ICRU Report 38, HDR brachytherapy is defined as dose rates exceeding 12 Gy/hour (0.2 Gy/min), typically delivered with Ir-192 sources in outpatient fractionated treatments.