Radiotherapy Questions and Answers

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Questions and Answers on Radiotherapy

1. What is the equivalent square field size of a rectangular 10 x 15 cm2 field ?
(1) 11x 1 cm2
(2) 12 x 12cm2
(3) 13x 13 cm2
(4) 14x 14 cm2

2. What is the primary radiobiological rationale of accelerated hyperfractionation ?
(1) Reduce the extent of intra-tumoral hypoxia
(2) Reduce the level of acute normal tissue toxicity
(3) Diminish the repopulation of tumor cells
(4) Decrease late effects while improving tumor control

3. For a cervical brachytherapy implant using the Manchester system, which point should receive the highest dose ?
(1) Point A
(2) Point B
(3) Bladder point
(4) Rectum point

4. Charged particle interactions with matter are predominately mediated by which effect ?
(1) Photoelectric effect
(2) Compton effect
(3) Pair production
(4) Direct Ionization

5. How many times greater is the mass of a proton compared to an electron ?
(1) 20
(2) 200
(3) 2,000
(4) 20,000

6. With a patient in the head-first supine position, an anterior-posterior (AP) beam is delivered on a linear accelerator using International electro-technical Commission (IEC) standards. What is the gantry angle?
(1) 0°
(2) 90°
(3) 180°
(4) 270°

7. Which electron energy exhibits the lowest surface dose ?
(1) 6 MeV
(2) 9 MeV
(3) 12 MeV
(4) 15 MeV

8. The typical cell cycle time (TC) for proliferating cells in human tumors is in the range of
(1) <1 day
(2) 1-5 days
(3) 6-25 days
(4) 26-100 days

9. High LET radiation are beneficial over low LET X-rays in treating tumors under which environmental constraint ?
(1) Hypoxia
(2) Hyperthermia
(3) High vascularization
(4) Low inflammation

10. In ICRU-83, what is the planning organ at risk volume (PRV) ?
(1) Volume to account for motion of the target to an organ at risk
(2) Volume to account for uncertainties and variations in position of a specific organ
(3) Volume that delineates the portion of an organ that is most at risk
(4) Volume of a parallel organ that is critical for radiation injury

11. What advantage does MV portal imaging offer when compared to kV planar imaging ?
(1) It allows for better soft tissue contrast for kV portal imaging
(2) It delivers a lower imaging dose than kV planar imaging
(3) It allows for the visualization of the treatment field with blocking
(4) It is uniquely capable of verifying that the patient is setup to isocenter

12. Which linear accelerator head component is necessary when delivering an electron beam ?
(1) Target
(2) Scattering foil
(3) Multi-leaf collimator (MLC)
(4) Jaw collimators

13. Why more monitor units are typically required for IMRT than for 3D CRT?
(1) Dose per fraction is typically higher for IMRT than for 3D CRT
(2) A higher beam energy is used for IMRT than for 3D CRT
(3) IMRT employs more fields than 3D CRT
(4) Large portions of the fields are blocked in IMRT compared to 3D CRT

14. What is the principal interaction process of megavoltage X-rays in tissue ?
(1) Pair production
(2) Photoelectric effect
(3) Compton effect
(4) Coherent scatter

15. Globally, what percent of cancer is estimated to be caused by infections?
(1) 1-2
(2) 5-10
(3) 15-20
(4) 40-50

16. DNA double strand breaks are repaired by which mechanism ?
(1) Mismatch repair
(2) Base Excision repair
(3) Nucleotide Excision Repair
(4) Nonhomologous End-Joining

17. Which treatment technique is most demanding on the performance and accuracy of a treatment delivery system ?
(1) 3D conformal therapy
(2) Volumetric-modulated arc therapy
(3) Conformal arc therapy
(4) Segmental intensity-modulated radiation therapy

18. Which of the following is an advantage of MR imaging over CT imaging ?
(1) MRI has better geometric accuracy
(2) MRI has smaller voxel sizes
(3) MRI provides electron density information
(4) MRI generates image sets in axial, sagittal, coronal or oblique planes

19. If the energy of an electron beam is increased for a treatment, what happens to the skin dose ?
(1) Increases
(2) Decreases
(3) Stays the same
(4) Depends on the energies used

20. Which cancer may be treated with radioactive iodine ?
(1) VIPoma
(2) Hurthle cell cancer
(3) Medullary thyroid cancer
(4) Anaplastic thyroid cancer

21. A miultifraction protocol for cancer cells exposed to x-rays produces an effective survival curve that is :
(1) Linear-quadratic
(2) Linear
(3) Parabolic
(4) Exponential

22. Which of the following match-up concerning radiation units is false ?
(1) KERMA- Curie
(2) Absorbed dose- Gray
(3) Exposure-Roentgen
(4) Equivalent dose-Sievert

23. An accidental exposure to a radiation source is reported one month following irradiation of a person not wearing a dosimeter. Which of the following assay would represent the best method to estimate the radiation dose received by this person ?
(1) Alkaline elution
(2) Staining with a monoclonal antibody to gamma-H2AX
(3) Karyotyping peripheral blood lymphocyte
(4) Pulsed-field gel electrophoresis

24. Which of the following research designs are the quickest and least expensive studies to undertake ?
(1) Clinical Trials
(2) Cohort Studies
(3) Case Control Studies
(4) Cross-Sectional Studies

25. The main cause of death from the hematopoietic syndrome is :
(1) Hypotension arising from microvascular destruction
(2) Haemolytic anemia
(3) Infection and haemorrhage resulting from loss of white cells and platelets
(4) Loss of erythrocytes resulting in organ ischemia

26. What was the most significant factor associated with secondary sarcoma development after treatment of childhood cancer ?
(1) Radiation dose
(2) Anthracycline exposure
(3) Age at treatment
(4) Gender

27. A 60-year-old post-menopausal woman has completed adjuvant chemotherapy for a stage II breast cancer. The cancer was ER+, PR+ and her2/neu negative. She had a mastectomy as initial treatment. Which of the following is the most appropriate next step to reduce her risk of recurrence ?
(1) An aromatase inhibitor for 5 to 10 years
(2) Tamoxifen for 5 years followed by an aromatase inhibitor for 5 years
(3) Tamoxifen for 2 years followed by an aromatase inhibitor for 3 years
(4) Tamoxifen for 5 to 10 years

28. Continuous hyper-fractionated accelerated radiation therapy (CHART) involved all except –
(1) Short overall treatment time of 12 consecutive days
(2) Three fractions of radiation per day
(3) Six day per week radiotherapy
(4) Low dose per fraction (1.4 — 1.5 Gy)

29. Which of the following is considered a postoperative chemoradiotherapy indication in cervical cancer ?
(1) Positive surgical margin
(2) Tumor size >4 cm
(3) Deep stromal invasion
(4) Clear cell histology

30. A 71-year-old woman diagnosed with 7 left ovarian mass in pelvic ultrasound. CT abdomen/pelvis reveals left inguinal lymphadenopathy. She undergoes full cytoreductive surgery with left inguinal lymphadenectomy. Pathology is significant for 2.5 cm left overian papillary serous carcinoma, implants on the left fallopian tube, one left pelvic lymph node and two left inguinal lymph nodes. What is the stage?
(1) I
(2) II
(3) IV
(4) III

31. Optimal treatment strategy for stage II-III soft tissue sarcomas extremity
(1) Surgery + IORT
(2) Surgery + adjuvant chemotherapy
(3) Surgery + chemoradiotherapy
(4) Preoperative radiotherapy = + surgery

32. A 55 year male with oropharyngeal cancer stage T3N2 stage IVa was treated with cisplatin and radiation for 7 weeks. He completed his therapy 12 months ago. Now complains severe fatigue, forgetfulness, dry skin, no sexual drive. He has dry mouth, but he can cat solid food. Which of the following is the most appropriate next step ?
(1) Order PET/CT scan to rule out brain metastatic disease
(2) Check TSH and free T4
(3) Explain to patient that this is normal part of the process and he may never feel back to normal
(4) Send patient to psychiatrist to evaluate for possible depression.

33. What is the most significant prognostic risk factor regarding early breast cancer ?
(1) Number of involved regional nodes
(2) hormone receptors —Ve
(3) High K167 proliferation markers
(4) Larger initial size

34. Tamoxifen and aromatase inibitors can be used in the treatment of ER+/PR+ breast cancer. In port-menopausal women, which of the following side effect profiles would favour the use of tamoxifen over aromatase inhibitors ?
(1) Fracture risk
(2) Hot flushes
(3) Vaginal bleeding
(4) Uterine cancer

35. Which of the following parameters is not used in the Van Nuys prognostic index ?
(1) Size
(2) Grade
(3) Surgical margin
(4) Hormone receptor status

36. Which is not a paraneoplastic syndrome associated with small cell Lung Cancer ?
(1) Ectopic Cushing’s syndrome
(2) Lambert-Eaton syndrome
(3) Sweet’s Syndrome
(4) Dermatomyositis

37. What was the total preoperative RT dose for initially unresectable vulvar cancer in the GOG 205 study when given along with weekly cisplatin chemotherapy ?
(1) 45 Gy
(2) 50.4 Gy
(3) 57.6 Gy
(4) 63 Gy

38. According to the RTOG breast cancer contouring atlas, what is included in the chest wall CTV for a patient receiving PMRT ?
(1) Mastectomy scar and chest wall excluding pectoralis muscles and ribs
(2) Mastectomy scar and chest wall including pectoralis muscles and excluding ribs
(3) Mastectomy scar and chest wall including pectoralis muscles and ribs, excluding latissimus dorsi muscle
(4) Mastectomy scar and chest wall including pectoralis muscles, ribs and latissimus dorsi muscle

39. What is the estimated rate of radio necrosis in modern studies following intracranial radiosurgery alone ?
(1) 1%
(2) 5%
(3) 9%
(4) 13%

40. What was the difference in 3-year OS between HPV +ve and HPV —ve oropharyngeal cancer patients in the RTOG 0129 trial ?
(1) 5%
(2) 25%
(3) 45%
(4) 65%

41. Which one of these breast cancer histologies is most favourable outcome?
(1) Apocrine
(2) Pleomorphic lobular
(3) Medullary
(4) Metaplastic

42. Which patient would be considered “Suitable” for consideration of APBI according to the updates ASTRO consensus statement ?
(1) 42 yr old, pT1NO ER positive ILC, 3 mm margins
(2) 52 yr old, pTINO ER positive IDC, 2 mm margins
(3) 62 yr old, pTINO ER negative IDC, 3 mm margins
(4) 62 yr old, pTis, 1.5 cm, low grade, 2 mm margins

43. What imaging feature is characteristic of a low grade oligodendrogliomas?
(1) Haemorrhage
(2) Calcification
(3) Occipital lobe location
(4) Ring-enhancement

44. What is hybrid brachytherapy in cervical cancer?
(1) Interdigitated EBRT and brachytherapy
(2) Combination of intracavitary and interstitial source placement
(3) Delivery of brachytherapy after EBRT
(4) Addition of weekly chemotherapy

45. For locoregionally advanced cancer Nasopharynx, which induction chemotherapy regimen given prior to concurrent chemo-radiotherapy improved OS compared to standard in a randomized controlled Phase III trial ?
(1) Cetuximab
(2) Carboplatin and paclitaxel
(3) Gemcitabine and cisplatin
(4) Carboplatin and 5-fluorouracil