ABR Radiation Oncology Certification
Examination Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. The most common histology of non-small cell lung cancer (NSCLC) is:
A) Small cell carcinoma
B) Squamous cell carcinoma
C) Adenocarcinoma
D) Large cell carcinoma
C) Adenocarcinoma
Rationale: Adenocarcinoma is now the most prevalent subtype of
NSCLC, particularly in non-smokers.
2. The alpha/beta ratio is highest in which type of tissue?
A) Late-responding normal tissue
, B) Tumor tissue with rapid proliferation
C) Early-responding normal tissue
D) Fibrotic tissue
C) Early-responding normal tissue
Rationale: Early-responding tissues like skin and mucosa have a high
alpha/beta ratio, reflecting sensitivity to fraction size.
3. In Hodgkin lymphoma, the standard radiation field for early-stage
disease is:
A) Whole body
B) Involved field
C) Mantle field
D) Total lymphoid irradiation
B) Involved field
Rationale: Modern practice favors involved-field radiation to
minimize exposure while maintaining disease control.
4. Which imaging modality is most sensitive for detecting intracranial
metastases?
A) CT with contrast
B) MRI with contrast
C) PET/CT
D) Ultrasound
B) MRI with contrast
, Rationale: MRI with contrast provides superior soft tissue resolution,
making it the most sensitive for brain metastases.
5. The primary mechanism of cell kill in radiation therapy is:
A) Protein denaturation
B) DNA damage
C) Membrane disruption
D) Mitochondrial dysfunction
B) DNA damage
Rationale: Ionizing radiation primarily kills cells by inducing DNA
double-strand breaks.
6. Which of the following is a dose-limiting toxicity for cranial irradiation
in children?
A) Alopecia
B) Neurocognitive decline
C) Nausea
D) Dermatitis
B) Neurocognitive decline
Rationale: Pediatric brain irradiation can cause long-term
neurocognitive deficits, making it a key dose-limiting factor.
7. The linear-quadratic model is used to:
A) Predict organ motion
B) Calculate tumor control probability
C) Describe fractionation sensitivity
, D) Estimate toxicity of chemotherapy
C) Describe fractionation sensitivity
Rationale: The linear-quadratic model characterizes the effect of
dose per fraction on tissue response.
8. The typical treatment for localized prostate cancer with intermediate
risk is:
A) Radical prostatectomy alone
B) External beam radiation therapy ± androgen deprivation therapy
C) Watchful waiting
D) Chemotherapy
B) External beam radiation therapy ± androgen deprivation therapy
Rationale: EBRT combined with short-term ADT improves outcomes
for intermediate-risk patients.
9. The most common late toxicity after thoracic radiation is:
A) Esophagitis
B) Pneumonitis
C) Fatigue
D) Alopecia
B) Pneumonitis
Rationale: Radiation-induced pneumonitis can occur months after
treatment and is the most significant late thoracic toxicity.
10. Which of the following cancers is most radiosensitive?
A) Melanoma
Examination Practice Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. The most common histology of non-small cell lung cancer (NSCLC) is:
A) Small cell carcinoma
B) Squamous cell carcinoma
C) Adenocarcinoma
D) Large cell carcinoma
C) Adenocarcinoma
Rationale: Adenocarcinoma is now the most prevalent subtype of
NSCLC, particularly in non-smokers.
2. The alpha/beta ratio is highest in which type of tissue?
A) Late-responding normal tissue
, B) Tumor tissue with rapid proliferation
C) Early-responding normal tissue
D) Fibrotic tissue
C) Early-responding normal tissue
Rationale: Early-responding tissues like skin and mucosa have a high
alpha/beta ratio, reflecting sensitivity to fraction size.
3. In Hodgkin lymphoma, the standard radiation field for early-stage
disease is:
A) Whole body
B) Involved field
C) Mantle field
D) Total lymphoid irradiation
B) Involved field
Rationale: Modern practice favors involved-field radiation to
minimize exposure while maintaining disease control.
4. Which imaging modality is most sensitive for detecting intracranial
metastases?
A) CT with contrast
B) MRI with contrast
C) PET/CT
D) Ultrasound
B) MRI with contrast
, Rationale: MRI with contrast provides superior soft tissue resolution,
making it the most sensitive for brain metastases.
5. The primary mechanism of cell kill in radiation therapy is:
A) Protein denaturation
B) DNA damage
C) Membrane disruption
D) Mitochondrial dysfunction
B) DNA damage
Rationale: Ionizing radiation primarily kills cells by inducing DNA
double-strand breaks.
6. Which of the following is a dose-limiting toxicity for cranial irradiation
in children?
A) Alopecia
B) Neurocognitive decline
C) Nausea
D) Dermatitis
B) Neurocognitive decline
Rationale: Pediatric brain irradiation can cause long-term
neurocognitive deficits, making it a key dose-limiting factor.
7. The linear-quadratic model is used to:
A) Predict organ motion
B) Calculate tumor control probability
C) Describe fractionation sensitivity
, D) Estimate toxicity of chemotherapy
C) Describe fractionation sensitivity
Rationale: The linear-quadratic model characterizes the effect of
dose per fraction on tissue response.
8. The typical treatment for localized prostate cancer with intermediate
risk is:
A) Radical prostatectomy alone
B) External beam radiation therapy ± androgen deprivation therapy
C) Watchful waiting
D) Chemotherapy
B) External beam radiation therapy ± androgen deprivation therapy
Rationale: EBRT combined with short-term ADT improves outcomes
for intermediate-risk patients.
9. The most common late toxicity after thoracic radiation is:
A) Esophagitis
B) Pneumonitis
C) Fatigue
D) Alopecia
B) Pneumonitis
Rationale: Radiation-induced pneumonitis can occur months after
treatment and is the most significant late thoracic toxicity.
10. Which of the following cancers is most radiosensitive?
A) Melanoma
