Radiation Oncology Basics Practice Questions

Q: The important symptom of radiation proctitis is:

Bleeding per rectum. **Explanation:** **Radiation proctitis** is a common complication following pelvic radiotherapy (for cancers of the cervix, prostate, or bladder). It occurs due to the proximity of the rectum to these pelvic organs, making it susceptible to radiation-induced mucosal damage. **Why "Bleeding per rectum" is correct:** The hallmark of chronic radiation proctitis is **painless rectal bleeding (hematochezia)**. Pathophysiologically, radiation causes obliterative endarteritis and mucosal ischemia, leading to the formation of fragile, superficial **telangiectasias**. These neovascular vessels bleed easily upon contact with stool. Other common symptoms include tenesmus and mucus discharge. **Why the other options are incorrect:** * **Weight loss (Options B & C):** While weight loss is a systemic sign of advanced malignancy or malabsorption, it is not a primary or specific symptom of radiation proctitis itself. Proctitis is a localized inflammatory/vascular process. * **Colicky abdominal pain (Option D):** This is more characteristic of intestinal obstruction or small bowel radiation enteritis. Radiation proctitis typically presents with pelvic discomfort or tenesmus rather than generalized colicky abdominal pain. **High-Yield Clinical Pearls for NEET-PG:** * **Acute vs. Chronic:** Acute proctitis occurs within 6 weeks (due to direct mucosal injury); Chronic proctitis occurs months to years later (due to ischemia and fibrosis). * **Endoscopic Finding:** The classic finding on sigmoidoscopy is **multiple telangiectasias** and pale, friable mucosa. * **Treatment:** The first-line treatment for symptomatic bleeding is often **Sucralfate enemas**. For refractory cases, **Argon Plasma Coagulation (APC)** is the gold standard for cauterizing telangiectasias.

Q: After how many days of radiotherapy, mucositis typically appears?

14 days. **Explanation:** Oral mucositis is a common acute complication of radiotherapy, particularly in head and neck cancers. The timing of its onset is dictated by the **kinetics of the oral mucosal epithelium.** 1. **Why 14 days is correct:** The oral mucosa has a rapid cell turnover rate, typically renewing every 10–14 days. Radiotherapy causes DNA damage to the basal germinal cells, inhibiting their ability to proliferate. As the existing mature superficial cells are naturally shed and not replaced by new cells from the basal layer, the mucosal lining thins and eventually breaks down. This process clinically manifests as erythema and ulceration (mucositis) typically at the **end of the second week (14 days)** of standard fractionated radiotherapy (2 Gy/day). 2. **Analysis of Incorrect Options:** * **7 days:** While microscopic damage begins immediately, the superficial layer remains intact for the first week; only mild erythema may be seen. * **10 days:** This is the early transition phase, but frank mucositis usually peaks and becomes clinically significant around day 14. * **30 days:** By this time, mucositis is usually at its peak or beginning to heal if the treatment course is short. 30 days is too late for the *initial* appearance. **High-Yield Clinical Pearls for NEET-PG:** * **Definition of Acute vs. Late effects:** Acute effects (like mucositis) occur within **90 days** of starting therapy; late effects occur after 90 days. * **Grading:** The WHO or RTOG scales are used to grade mucositis (Grade 1: Erythema; Grade 2: Isolated ulcers; Grade 3: Confluent ulcers; Grade 4: Hemorrhage/Necrosis). * **Management:** "Magic mouthwash" (containing lidocaine, antacids, and diphenhydramine) and Palifermin (recombinant keratinocyte growth factor) are high-yield management options. * **Recovery:** Mucositis usually resolves 2–4 weeks after the completion of radiotherapy.

Q: What is the maximum radiation dose to point A for early and advanced Ca cervix?

80-85 Gy and 85-90 Gy. In Carcinoma Cervix, the total radiation dose is a combination of **External Beam Radiotherapy (EBRT)** and **Brachytherapy**. The target for dose prescription is **Point A**, located 2 cm superior to the lateral vaginal fornix and 2 cm lateral to the uterine canal. ### Why Option A is Correct The standard therapeutic window for Point A aims to achieve local control while minimizing toxicity to the rectum and bladder. * **Early-stage (IB1, IIA1):** A total dose of **80–85 Gy** is sufficient for smaller tumor volumes. * **Advanced-stage (IIB, III, IVA):** Due to larger tumor bulk and parametrial involvement, a higher dose of **85–90 Gy** is required to achieve optimal tumor regression. ### Explanation of Incorrect Options * **Option B (85–95 Gy):** These doses exceed the tolerance limits of the surrounding pelvic organs (Rectum and Bladder), significantly increasing the risk of radiation proctitis and fistulas. * **Options C & D (70–85 Gy):** These doses are generally considered sub-therapeutic for definitive management of advanced cervical cancer, leading to higher rates of local recurrence. ### High-Yield Clinical Pearls for NEET-PG * **Point A:** Represents the crossing of the **Ureter and Uterine Artery**. It is the primary point for dose prescription. * **Point B:** Located 3 cm lateral to Point A (5 cm from the midline). It represents the **Obturator nodes** and pelvic wall involvement. * **Manchester System:** The classic system used for cervical brachytherapy dosimetry. * **ICRU 38/89:** Modern guidelines emphasize GEC-ESTRO recommendations, moving from 2D points (Point A) to 3D volume-based planning (HR-CTV).

Q: Which of the following is the most beneficial technique of using chemotherapy with a course of radiotherapy in head and neck malignancies?

Concurrent chemotherapy. **Explanation:** In the management of locally advanced Head and Neck Squamous Cell Carcinomas (HNSCC), **Concurrent Chemoradiotherapy (CCRT)** is considered the gold standard. The primary medical concept behind this is **radiosensitization**. Chemotherapeutic agents (most commonly Cisplatin) act as "sensitizers" that inhibit the repair of sublethal radiation damage in tumor cells and promote synchronization of the cell cycle into the G2/M phase, which is the most radiosensitive phase. This synergy results in superior locoregional control and overall survival compared to radiotherapy alone. **Analysis of Incorrect Options:** * **Neo-adjuvant (Induction) Chemotherapy:** Given before radiotherapy to shrink the tumor. While it may reduce distant metastasis, it has not consistently shown an improvement in overall survival compared to CCRT and may delay definitive local treatment. * **Adjuvant Chemotherapy:** Given after the primary treatment (surgery or RT). In head and neck cancers, its role is limited as it does not significantly improve survival once the primary treatment is completed. * **Alternating Chemotherapy and Radiotherapy:** This involves giving cycles of CT and RT sequentially. It is logistically complex and has been largely superseded by concurrent protocols which offer better biological synergy. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** **Cisplatin** is the most common agent used concurrently with RT in head and neck cancers. * **Spatial Cooperation:** Chemotherapy treats micrometastases (systemic) while RT treats the primary site (local). * **P16 Status:** In Oropharyngeal cancers, HPV/p16 status is a crucial prognostic factor, though CCRT remains a mainstay for advanced stages. * **Toxicities:** While CCRT is most effective, it also increases acute toxicities like severe mucositis and dysphagia.

Q: What dose of radiation therapy is recommended for pain relief in bone metastases?

8 Gy in one fraction. **Explanation:** **1. Why 8 Gy in one fraction is correct:** The primary goal of radiotherapy for bone metastases is **palliation** (pain relief and prevention of skeletal-related events). Multiple randomized controlled trials and international guidelines (ASTRO/ESTRO) have established that **8 Gy in a single fraction** is as effective as longer courses for pain control. It is the preferred regimen because it is convenient for the patient, cost-effective, and minimizes hospital visits for terminally ill patients. **2. Analysis of Incorrect Options:** * **B (20 Gy in 5 fractions) & C (30 Gy in 10 fractions):** These are "multi-fraction" palliative regimens. While they are frequently used in clinical practice (especially if there is an associated soft tissue mass or for spinal stability), they do not provide superior pain relief compared to the 8 Gy single dose. In the context of NEET-PG, 8 Gy is the "gold standard" answer for simple pain relief. * **D (Above 70 Gy):** This is a **radical/curative dose** used for primary epithelial tumors (like Head and Neck cancers). Such high doses would cause significant toxicity and are never used for palliative bone metastasis treatment. **3. Clinical Pearls for NEET-PG:** * **Pain Relief Onset:** Improvement usually begins within 1–2 weeks, with maximum relief at 4 weeks. * **Re-treatment:** Single-fraction (8 Gy) carries a higher rate of "re-treatment" compared to multi-fraction regimens, but the overall pain response rate is identical. * **Pathological Fractures:** If a fracture has already occurred, surgical fixation followed by multi-fraction RT (e.g., 30 Gy/10 fractions) is usually preferred over a single dose. * **Strontium-89 / Samarium-153:** These are systemic radiopharmaceuticals used for widespread, diffuse "blastic" bone metastases (e.g., Prostate cancer).

Q: Mega voltage therapy consists of:

Greater than 1000 kV. **Explanation:** The classification of radiotherapy is primarily based on the energy (voltage) of the X-ray beams used. **Megavoltage therapy** refers to radiation treatment using photon beams with energies of **1 MeV (1000 kV) or higher**. 1. **Why Option A is correct:** By definition, megavoltage equipment (such as Linear Accelerators/LINAC and Cobalt-60 units) operates in the range of 1 MV to 25 MV. These high-energy beams are essential in modern oncology because they provide a **"skin-sparing effect,"** where the maximum dose is delivered at a specific depth below the skin surface (e.g., 1.5 cm for 6 MV), reducing the risk of severe radiation dermatitis. 2. **Why other options are incorrect:** * **Option B & C:** These fall under **Orthovoltage therapy** (typically 150–500 kV) or **Deep therapy**. These lower energies have poor penetration and cause maximum dose deposition on the skin surface, making them unsuitable for deep-seated tumors. * **Option D:** While 2000 kV is technically megavoltage, it is a subset of the "Greater than 1000 kV" category. Option A is the standard threshold definition used in radiological physics. **High-Yield Clinical Pearls for NEET-PG:** * **Grenz Rays:** Very low energy (<20 kV). * **Superficial Therapy:** 50–150 kV (used for skin lesions). * **Cobalt-60:** A common megavoltage source emitting gamma rays at **1.17 and 1.33 MeV** (Average: 1.25 MeV). * **Advantages of Megavoltage:** Greater penetration (depth dose), skin-sparing effect, and reduced bone absorption (less risk of osteoradionecrosis) compared to orthovoltage.

Q: Intracavitary radiation is indicated in which of the following conditions?

Carcinoma of the cervix. **Explanation:** **Intracavitary Brachytherapy** is a form of internal radiation where radioactive sources are placed directly into a body cavity near the tumor site. **Why Carcinoma of the Cervix is Correct:** The most classic and common indication for intracavitary radiation is **Carcinoma of the Cervix**. The anatomy of the vagina and the cervical canal allows for the insertion of specialized applicators (like Tandem and Ovoids or Tandem and Ring). This technique delivers a high dose of radiation directly to the tumor while rapidly "falling off" to spare adjacent critical structures like the bladder and rectum. It is a cornerstone of curative treatment in cervical cancer. **Why the Other Options are Incorrect:** * **Carcinoma of the Lung:** Usually treated with External Beam Radiation Therapy (EBRT). While *intraluminal* brachytherapy (via bronchoscopy) is possible for endobronchial lesions, it is not the standard "intracavitary" approach. * **Carcinoma of the Oesophagus:** Similar to the lung, this requires *intraluminal* brachytherapy. Intracavitary refers to natural body cavities (like the uterus/vagina), whereas intraluminal refers to the lumen of a tube. * **Carcinoma of the Oral Cavity:** This typically requires **Interstitial Brachytherapy**, where radioactive needles or seeds are implanted directly into the tongue or buccal tissues. **High-Yield Clinical Pearls for NEET-PG:** * **Types of Brachytherapy:** * **Intracavitary:** Cervix, Endometrium. * **Interstitial:** Breast, Tongue (Oral cavity), Prostate, Soft tissue sarcoma. * **Surface Mold:** Skin cancers, Hard palate. * **Intraluminal:** Oesophagus, Bronchus, Bile duct. * **Isotopes used:** **Iridium-192** (most common for HDR), Cesium-137, and Cobalt-60. * **Manchester System:** A classic dosimetry system used in cervical brachytherapy to define **Point A** (2cm lateral and 2cm superior to the external os).

Q: The Marx protocol for osteoradionecrosis is related to which of the following?

Hyperbaric oxygen therapy. **Explanation:** The **Marx Protocol** is the gold-standard therapeutic framework for managing **Osteoradionecrosis (ORN)** of the jaw. It is fundamentally based on the use of **Hyperbaric Oxygen (HBO) therapy**. **Why Option B is correct:** The underlying pathophysiology of ORN, as described by Marx, is the **"3-H" principle**: Hypovascularity, Hypocellularity, and Hypoxia. Radiation damages the microvasculature, leading to chronic tissue ischemia. HBO therapy works by increasing the partial pressure of oxygen in the tissues, which stimulates **angiogenesis** and **collagen synthesis**, thereby promoting healing in the necrotic bone. The protocol typically involves "20 dives" (sessions) of HBO before surgery and "10 dives" after surgery (the 20/10 rule). **Why other options are incorrect:** * **Option A & C:** While antibiotics may be used to manage secondary superficial infections in ORN, they are **not** the core component of the Marx Protocol. ORN is primarily a non-healing, hypoxic wound rather than a primary bacterial infection (like osteomyelitis). Therefore, high-dose antibiotics alone cannot reverse the underlying vascular damage. **High-Yield Clinical Pearls for NEET-PG:** * **Definition of ORN:** Exposed bone in a previously irradiated area that fails to heal over a period of 3–6 months. * **Most Common Site:** The **Mandible** (due to its lower vascularity compared to the maxilla). * **Marx Classification:** Stages ORN from I to III based on the response to HBO and the extent of bone destruction. * **PENTOCLO Protocol:** A newer pharmacological alternative to Marx, involving Pentoxifylline, Tocopherol (Vitamin E), and Clodronate.

Q: Concomitant chemoradiotherapy is indicated in all of the following malignancies except?

T2 N0 M0 Glottic Cancer. **Explanation** The core concept in oncology management is distinguishing between **definitive radiotherapy** (single modality) and **concomitant chemoradiotherapy (CCRT)** (multimodality). CCRT uses chemotherapy as a "radiosensitizer" to enhance the cell-killing effect of radiation in locally advanced or high-risk tumors. **Why Option C is the Correct Answer:** **T2 N0 M0 Glottic Cancer** is considered an early-stage laryngeal malignancy. The standard of care for early glottic cancer (T1-T2, N0) is **single-modality therapy**, either definitive Radiotherapy (RT) or conservative surgery (e.g., laser excision). Chemotherapy is not indicated because it adds significant toxicity without providing a survival benefit in these early stages. CCRT in the larynx is reserved for locally advanced stages (T3-T4) as part of organ-preservation protocols. **Analysis of Incorrect Options:** * **Stage IIIB Ca Cervix:** This is locally advanced cervical cancer. CCRT with Cisplatin is the global standard of care (Eversley protocol) for all stages from IB3 to IVA. * **T2 N0 M0 Anal Cancer:** Unlike other GI cancers, anal canal cancer is primarily treated with the **Nigro Protocol** (CCRT with 5-FU and Mitomycin-C), regardless of the small size, to avoid permanent colostomy. * **T1 N2 M0 Nasopharyngeal Cancer:** Nasopharyngeal carcinoma is highly radiosensitive but also has a high risk of distant metastasis. Even with a small primary (T1), the presence of nodal involvement (N2) necessitates CCRT. **High-Yield Clinical Pearls for NEET-PG:** * **Radiosensitizer of choice:** Cisplatin is the most common agent used in CCRT for head, neck, and cervical cancers. * **Nigro Protocol:** Definitive CCRT for Anal Canal Cancer (avoids surgery). * **Early Glottic Cancer:** Has an excellent prognosis with RT alone (90%+ control rates). * **Concurrent vs. Adjuvant:** Concurrent means "at the same time," whereas adjuvant means "after the primary treatment."

Q: Mantel radiation therapy is indicated for which of the following conditions?

Hodgkin's lymphoma. **Explanation:** **Mantel field radiation** is a classic radiotherapy technique historically used as the standard of care for **Hodgkin’s Lymphoma (HL)**. It is designed to treat all lymph node stations above the diaphragm while shielding the lungs, heart, and spinal cord. 1. **Why Hodgkin’s Lymphoma is Correct:** HL typically spreads in a predictable, contiguous fashion through lymphatic chains. The Mantel field covers the submandibular, cervical, supraclavicular, infraclavicular, axillary, and mediastinal nodes in a single portal. While modern practice has shifted toward "Involved Site Radiation Therapy" (ISRT) to reduce toxicity, Mantel radiation remains the definitive historical association for HL in exams. 2. **Why Other Options are Incorrect:** * **Non-Hodgkin’s Lymphoma (NHL):** Unlike HL, NHL is often widespread and non-contiguous at presentation, making localized "field" radiation like the Mantel field less effective as a primary strategy. * **Burkitt’s Lymphoma:** This is a highly aggressive B-cell NHL characterized by rapid systemic spread. Treatment is primarily intensive systemic chemotherapy; radiation plays a very limited role. * **Mycosis Fungoides:** This is a cutaneous T-cell lymphoma. The standard radiation treatment is **Total Electron Beam Skin Irradiation (TSET)**, not nodal field radiation. **High-Yield Clinical Pearls for NEET-PG:** * **Inverted Y Field:** Used to treat nodes below the diaphragm (iliac, inguinal, and para-aortic nodes). * **Total Nodal Irradiation (TNI):** A combination of the Mantel field and the Inverted Y field. * **Complications of Mantel Field:** Increased risk of secondary malignancies (Breast cancer, Papillary Thyroid cancer), premature coronary artery disease, and hypothyroidism. * **Lhermitte’s Sign:** An electric-shock sensation down the spine upon neck flexion, sometimes seen after Mantel radiation due to transient myelopathy.

Question 1

The important symptom of radiation proctitis is:

Accepted Answer

Bleeding per rectum

Answer

Weight loss

Answer

Loss of weight

Answer

Colicky abdominal pain

Question 2

After how many days of radiotherapy, mucositis typically appears?

Accepted Answer

14 days

Answer

7 days

Answer

10 days

Answer

30 days

Question 3

What is the maximum radiation dose to point A for early and advanced Ca cervix?

Accepted Answer

80-85 Gy and 85-90 Gy

Answer

85-90 Gy and 90-95 Gy

Answer

75-80 Gy and 80-85 Gy

Answer

70-75 Gy and 75-80 Gy

Question 4

Which of the following is the most beneficial technique of using chemotherapy with a course of radiotherapy in head and neck malignancies?

Accepted Answer

Concurrent chemotherapy

Answer

Neo adjuvant chemotherapy

Answer

Adjuvant chemotherapy

Answer

Alternating chemotherapy and radiotherapy

Question 5

What dose of radiation therapy is recommended for pain relief in bone metastases?

Accepted Answer

8 Gy in one fraction

Answer

20 Gy in 5 fractions

Answer

30 Gy in 10 fractions

Answer

Above 70 Gy

Question 6

Mega voltage therapy consists of:

Accepted Answer

Greater than 1000 kV

Answer

500-1000 kV

Answer

Less than 500 kV

Answer

More than 2000 kV

Question 7

Intracavitary radiation is indicated in which of the following conditions?

Accepted Answer

Carcinoma of the cervix

Answer

Carcinoma of the lung

Answer

Carcinoma of the oesophagus

Answer

Carcinoma of the oral cavity

Question 8

The Marx protocol for osteoradionecrosis is related to which of the following?

Accepted Answer

Hyperbaric oxygen therapy

Answer

High dose antibiotic therapy

Answer

Both high dose antibiotic therapy and hyperbaric oxygen therapy

Answer

None of the above

Question 9

Concomitant chemoradiotherapy is indicated in all of the following malignancies except?

Accepted Answer

T2 N0 M0 Glottic Cancer

Answer

Stage III B Ca Cervix

Answer

T2 N0 M0 Anal Cancer

Answer

T1 N2 M0 Nasopharyngeal Cancer

Question 10

Mantel radiation therapy is indicated for which of the following conditions?

Accepted Answer

Hodgkin's lymphoma

Answer

Non-Hodgkin's lymphoma

Answer

Burkitt's lymphoma

Answer

Mycosis fungoides

Radiation Oncology Basics — MCQs

Radiation Oncology Basics — MCQs

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