Radiation Oncology Basics Practice Questions

Q: Compared to the other options, radiotherapy is LEAST commonly used as a primary treatment modality in:

Stomach cancer. ***Stomach cancer*** - **Radiotherapy** is generally *not* a primary treatment for **stomach cancer** due to the high radiosensitivity of surrounding organs (e.g., small bowel, liver, kidneys) and the difficulty in delivering a curative dose without significant toxicity. - While it may be used as an **adjuvant therapy** post-surgery or for **palliative care** (e.g., pain, bleeding), it is rarely the initial standalone treatment. *Esophageal cancer* - **Radiotherapy** is a common primary or neoadjuvant treatment for **esophageal cancer**, often in combination with chemotherapy (**chemoradiation**), especially for unresectable cases or to downstage tumors before surgery. - It plays a significant role in both curative intent and **palliative management** for dysphagia. *Brain tumor* - **Radiotherapy** is a cornerstone of treatment for many primary and metastatic **brain tumors**, often following surgical resection or as a standalone primary treatment. - Techniques like **stereotactic radiosurgery (SRS)** and **intensity-modulated radiation therapy (IMRT)** allow for precise targeting, minimizing damage to healthy brain tissue. *Cervical cancer* - **Radiotherapy**, particularly external beam radiation therapy (EBRT) combined with **brachytherapy**, is a highly effective primary treatment for **locally advanced cervical cancer**, especially if surgery is not feasible or desired [1]. - It can achieve high cure rates and is often given concurrently with chemotherapy (**chemoradiation**) [1].

Q: Which of the following elements is obsolete in radiotherapy:

Radium 226. ***Radium 226*** - **Radium 226** was one of the earliest radioactive sources used in brachytherapy but has largely been replaced due to its decay products producing **radon gas**, a toxic noble gas. - Its high **gamma energy** and long half-life made it difficult to shield and handle, leading to significant radiation safety concerns. *Iridium 192* - **Iridium 192** is a widely used radioisotope in **HDR (High-Dose Rate) brachytherapy** due to its relatively short half-life and suitable gamma energy for dose delivery. - It allows for flexible treatment planning and precise targeting in various cancer sites. *Cesium 137* - **Cesium 137** is commonly used in **LDR (Low-Dose Rate) brachytherapy** and some teletherapy units, offering a longer half-life than Iridium-192. - Its gamma energy is lower than that of Radium-226, making it safer to handle and shield. *Cobalt 60* - **Cobalt 60** was historically and is still used in **teletherapy units (gamma knives)** for external beam radiotherapy, especially for brain tumors. - Its high-energy gamma rays provide excellent dose penetration, though it has largely been replaced by linear accelerators in conventional external beam radiotherapy.

Q: Radiotherapy is most useful in:

Seminoma. ***Seminoma*** - **Seminoma** is a highly **radiosensitive** tumor, making radiotherapy a cornerstone of its treatment, especially for localized disease and in adjuvant settings. - Due to its chemosensitivity and radiosensitivity, even advanced seminoma often responds well to treatment, leading to **high cure rates**. *Melanoma* - **Melanoma** is generally considered **radioresistant**, meaning that it does not respond well to conventional doses of radiation. - Treatment primarily involves **surgical excision**, immunotherapy, and targeted therapies. *Pancreatic carcinoma* - **Pancreatic carcinoma** is notoriously **radioresistant** and has a poor prognosis, with limited effectiveness of standalone radiation therapy. - Treatment often involves a combination of **surgery**, chemotherapy, and sometimes concurrent chemoradiation, though outcomes remain challenging. *Osteosarcoma* - **Osteosarcoma** is primarily managed with **surgical resection** and **neoadjuvant/adjuvant chemotherapy**, as it is relatively radioresistant. - Radiotherapy is typically reserved for unresectable tumors, palliative care, or when surgery is contraindicated.

Q: The standard radiation therapy dose for consolidation treatment in early-stage Hodgkin lymphoma is:

Standard dose: 20-30 Gy. **Standard dose: 20-30 Gy** - For **early-stage Hodgkin lymphoma**, a dose range of **20-30 Gy** is considered standard for **consolidation radiotherapy** following chemotherapy. - This dose balances efficacy in eradicating residual microscopic disease with minimizing **long-term toxicity**. *Moderate dose: 30-40 Gy* - This dose range is typically used in situations requiring **higher local control** where the risk of recurrence is elevated, or for certain **bulky disease** settings. - It exceeds the standard recommendation for **routine consolidation** in early-stage disease due to potential for increased side effects. *High dose: 50-60 Gy* - Doses in this range are usually reserved for **definitive radiation therapy** in primary malignancy treatment or for **palliation of symptomatic bulky disease**, not early-stage consolidation. - Such high doses would significantly increase the risk of **secondary malignancies** and other late toxicities in Hodgkin lymphoma. *Intermediate dose: 40-50 Gy* - This dose range is generally not a recognized standard for **early-stage Hodgkin lymphoma consolidation**. - It falls between standard consolidation and definitive treatment doses, potentially offering **unjustified toxicity** without a clear benefit over the lower standard dose.

Q: Point A and point B Manchester locations are important for treatment of which cancer –

Cervix. ***Cervix*** - **Point A** and **Point B Manchester** locations are historical references used in **brachytherapy** for **cervical cancer**, defining critical dose points within the pelvis. - These points help guide the placement of radiation sources to ensure adequate tumor coverage while sparing surrounding healthy tissues. *Vagina* - While radiation therapy is used for vaginal cancer, the **Manchester system's Point A and B** are specifically defined for cervical anatomy, not primarily for vaginal tumors. - Different dosimetry systems or specific vaginal applicators are often used for vaginal brachytherapy. *Ovary* - Ovarian cancer is primarily treated with **surgery and chemotherapy**; external beam radiation is sometimes used, but brachytherapy with **Point A and B** is not a standard approach. - The anatomical location of the ovaries makes brachytherapy less suitable for delivering targeted, high-dose radiation compared to cervical cancer. *Uterus* - Endometrial (uterine) cancer treatment may involve brachytherapy, but it typically uses different applicators (e.g., **tandem and ovoids** or cylinders) and dose specifications that are distinct from the Manchester system's **Point A and B** for the cervix. - The geometry and treatment volumes for uterine brachytherapy are different due to the distinct anatomy and tumor spread patterns.

Q: Mantle Field Radiotherapy is generally used in treatment of?

Hodgkins Lymphoma. **Hodgkins Lymphoma** - **Mantle field radiotherapy** is a classic technique used to treat Hodgkin's lymphoma, particularly when the disease is localized to the **mediastinum, neck, and axillary lymph nodes** [1]. - This field encompasses the major lymphatic regions above the diaphragm, providing comprehensive treatment for common sites of involvement without exceeding dose limits to critical organs [1]. *Breast carcinoma* - Treatment for **breast carcinoma** typically involves surgery, chemotherapy, and localized radiation therapy to the breast and regional lymph nodes (axillary, supraclavicular, internal mammary), but not a widespread "mantle field." - Radiation fields for breast cancer are more specific to the breast tissue and regional nodes, aiming to minimize cardiac and pulmonary toxicity. *Neuroblastoma* - **Neuroblastoma** is a childhood cancer originating from neural crest cells and typically involves the adrenal glands or sympathetic ganglia; its treatment involves surgery, chemotherapy, and sometimes localized radiation, not mantle fields. - Radiation therapy for neuroblastoma is usually directed at specific tumor sites, such as the abdomen or chest, with techniques tailored to spare developing organs. *Lung cancer* - **Lung cancer** radiation therapy focuses on the primary tumor in the lung and involved mediastinal lymph nodes, using highly conformal techniques like IMRT or SBRT [2]. - A "mantle field" would be too broad and deliver unnecessary radiation to healthy lung tissue and other structures, increasing toxicity without improving outcomes for lung cancer.

Q: True about Gamma Knife radiotherapy

It is used for both benign and malignant cases. ***It is used for both benign and malignant cases*** - **Gamma Knife radiosurgery** precisely targets and treats various intracranial conditions, including both **benign tumors** (e.g., meningiomas, acoustic neuromas) and **malignant tumors** (e.g., metastatic brain lesions). - Its high precision allows for effective treatment while minimizing damage to surrounding healthy tissue. *Reduced blood loss in surgery* - While Gamma Knife is a **non-invasive procedure** that does not involve surgical incisions or general anesthesia, it is not a traditional "surgery" in the sense that involves blood loss. - The primary benefit is avoiding surgical risks, not reducing blood loss during an actual incision. *Gamma rays are emitted from uranium* - Gamma Knife technology utilizes **cobalt-60** as its radioactive source, not uranium. - Cobalt-60 emits **gamma rays** that are precisely focused to target the intended lesion. *It is a special kind of knife* - The term "knife" in Gamma Knife refers to its **precision and cutting-like accuracy** in targeting and ablating lesions, not to an actual surgical blade. - It is a form of **stereotactic radiosurgery**, delivering highly focused radiation beams.

Q: Stereotactic Radiotherapy is used in:

Inoperable Stage 1 Lung Tumor. ***Inoperable Stage 1 Lung Tumor*** - **Stereotactic Radiotherapy (SRT)** is highly effective for **inoperable Stage 1 lung tumors** because it delivers high doses of radiation with extreme precision, maximizing tumor control while sparing surrounding healthy tissue. - The **precision** of SRT makes it an excellent option for localized, small tumors that cannot be surgically removed due to patient comorbidities or tumor location. *Lymphangitis Carcinomatosa* - **Lymphangitis carcinomatosa** involves diffuse infiltration of the pulmonary lymphatic system by cancer cells and is not amenable to localized radiation techniques like SRT. - Treatment for lymphangitis carcinomatosa typically involves **systemic therapy** such as chemotherapy or targeted therapy, rather than focal radiation. *Miliary Lung Metastasis* - **Miliary lung metastases** refer to widespread, small (~2-4mm) nodules throughout both lungs, indicating advanced systemic disease. - SRT is a **localized treatment** and therefore not appropriate for diffuse, multifocal disease like miliary metastases, which requires systemic treatment. *Tumor at the base of tongue with new Lymph Node enlargement* - A tumor at the **base of the tongue with new lymph node enlargement** indicates a larger disease burden, likely requiring a combination of **surgery, conventional radiation therapy, and/or chemotherapy**. - While radiation is a component of treatment for head and neck cancers, **SRT is typically reserved for smaller, well-defined lesions**, or in specific cases as a boost or for recurrences, not usually for initial treatment of a larger primary tumor with nodal involvement.

Q: The ideal timing of radiotherapy for Wilms tumour after surgery is:

Within 10 days. ***Within 10 days*** - For patients with **Wilms tumour** requiring adjuvant radiotherapy, treatment should ideally commence within **10 days following surgery**. - This prompt initiation minimizes the time for any residual microscopic disease to proliferate and potentially spread, optimizing local control and overall outcome. *Any time after surgery* - This timing is too broad and does not adhere to the recommended protocol for Wilms tumour, which emphasizes early post-operative radiotherapy. - Delaying radiotherapy beyond the recommended window can increase the risk of tumour recurrence and negatively impact prognosis. *Within 2 weeks* - While 2 weeks is a relatively short timeframe, **10 days** is the more precise and **ideal window** for initiating radiotherapy according to established protocols for Wilms tumour. - Waiting up to 2 weeks (14 days) might still introduce an unnecessary delay compared to the optimal 10-day goal. *Within 3 weeks* - A delay of up to **3 weeks** is considered suboptimal and potentially risky, as it allows a longer period for any remaining tumour cells to regrow. - This interval significantly deviates from the **evidence-based guidelines** for timely adjuvant therapy in Wilms tumour management.

Question 1

Compared to the other options, radiotherapy is LEAST commonly used as a primary treatment modality in:

Accepted Answer

Stomach cancer

Answer

Esophageal cancer

Answer

Brain tumor

Answer

Cervical cancer

Question 2

Which of the following elements is obsolete in radiotherapy:

Accepted Answer

Radium 226

Answer

Iridium 192

Answer

Cesium 137

Answer

Cobalt 60

Question 3

Radiotherapy is most useful in:

Accepted Answer

Seminoma

Answer

Melanoma

Answer

Pancreatic carcinoma

Answer

Osteosarcoma

Question 4

The standard radiation therapy dose for consolidation treatment in early-stage Hodgkin lymphoma is:

Accepted Answer

Standard dose: 20-30 Gy

Answer

Moderate dose: 30-40 Gy

Answer

High dose: 50-60 Gy

Answer

Intermediate dose: 40-50 Gy

Question 5

Point A and point B Manchester locations are important for treatment of which cancer –

Accepted Answer

Cervix

Answer

Vagina

Answer

Ovary

Answer

Uterus

Question 6

Mantle Field Radiotherapy is generally used in treatment of?

Accepted Answer

Hodgkins Lymphoma

Answer

Breast carcinoma

Answer

Neuroblastoma

Answer

Lung cancer

Question 7

True about Gamma Knife radiotherapy

Accepted Answer

It is used for both benign and malignant cases

Answer

Reduced blood loss in surgery

Answer

Gamma rays are emitted from uranium

Answer

It is a special kind of knife

Question 8

Stereotactic Radiotherapy is used in:

Accepted Answer

Inoperable Stage 1 Lung Tumor

Answer

Lymphangitis Carcinomatosa

Answer

Miliary Lung Metastasis

Answer

Tumor at the base of tongue with new Lymph Node enlargement

Question 9

The ideal timing of radiotherapy for Wilms tumour after surgery is:

Accepted Answer

Within 10 days

Answer

Any time after surgery

Answer

Within 2 weeks

Answer

Within 3 weeks

Question 10

All of the following are true about long-term sequelae of craniospinal radiotherapy for children with CNS tumors except:

Accepted Answer

Neuropsychological sequelae are independent of radiation dose

Answer

Musculoskeletal hypoplasia

Answer

Neurocognitive dysfunction

Answer

Endocrinologic dysfunction

Radiation Oncology Basics — MCQs

Radiation Oncology Basics — MCQs

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