Radiation Oncology Basics Practice Questions

Q: Nowadays radium is not used in the Rx of cancer because:

It decays into daughter Radon which is a constant hazard. ***It decays into daughter Radon which is a constant hazard*** - Radium-226 decays into **Radon-222**, a radioactive gas that can leak from sealed sources or medical devices. - This **gaseous daughter product** poses a significant radiation hazard to patients and medical staff, necessitating extensive safety precautions. *It is a very unstable element* - While radium is a **radioactive element** and thus unstable, its inherent instability alone isn't the primary reason for its disuse in cancer therapy. - The specific hazard comes from **what it decays into**, not just the act of decay itself. *It decays faster and needs frequent replacement* - Radium-226 has a **half-life of 1600 years**, meaning it decays very slowly and would not require frequent replacement. - This long half-life is actually a characteristic that makes its daughter product, Radon-222, a persistent issue rather than a rapid decay being the problem. *It has a very long half life* - A long half-life (e.g., 1600 years for Radium-226) means the radioactive material persists for a very long time, leading to a **prolonged source of radiation**. - While this is true, the primary concern in its historical therapeutic use was the **radioactive gaseous daughter product**, Radon, which accumulates and poses an ongoing hazard.

Q: Chronic radiation proctitis is associated with the treatment of all malignancies, EXCEPT:

Carcinoma small bowel. Chronic radiation proctitis is associated with the treatment of all malignancies, EXCEPT: ***Carcinoma small bowel*** - **Radiation therapy** is rarely used as a primary treatment for **small bowel carcinoma**, as surgical resection is the main modality. - Therefore, the small bowel is typically not exposed to direct radiation in a manner that would cause proctitis. *Carcinoma cervix* - **Pelvic radiation** is a common treatment for **cervical carcinoma**, which often involves the rectum within the radiation field. - This proximity makes chronic radiation proctitis a known and relatively frequent complication. *Carcinoma prostate* - **External beam radiation therapy** is a standard treatment option for **prostate cancer**, directly targeting the prostate gland which is anatomically close to the rectum. - This close proximity frequently leads to chronic radiation-induced damage to the rectal tissue, resulting in proctitis. *Carcinoma testes* - While **testicular cancer** itself is not directly adjacent to the rectum, certain stages of testicular cancer are treated with **retroperitoneal lymph node irradiation** or whole-pelvis radiation. - This can expose portions of the rectum to radiation, leading to chronic radiation proctitis as a potential side effect.

Q: The ideal timing of radiotherapy for Wilms' tumor after surgery is -

Within 10 days. ***Within 10 days*** - Postoperative radiotherapy for Wilms' tumor should ideally be initiated within **10 days** of surgery to optimize outcomes and minimize the risk of recurrence. - This **early initiation** helps to control potential microscopic residual disease and is associated with improved outcomes. - **Children's Oncology Group (COG)** protocols recommend starting radiotherapy within **10-14 days**, with 10 days being the preferred timeline. *Any time after surgery* - Delaying radiotherapy beyond the recommended 10-14 day window can significantly increase the risk of **disease progression** and **local recurrence**. - The efficacy of radiotherapy is highest when administered promptly after surgical resection. *Within 2 months* - A delay of two months is considered **suboptimal** and significantly exceeds the recommended timeframe. - This extended delay could lead to progression of any residual tumor cells and compromise treatment outcomes. *Within 2 weeks* - While 2 weeks (14 days) falls within the acceptable **10-14 day window** recommended by most protocols, **10 days is preferred** as the most optimal timing. - The distinction is that initiating within 10 days is considered **ideal**, whereas the full 14-day period represents the outer limit of the acceptable timeframe for standard cases.

Q: Gamma knife utilizes -

Cobalt-60. ***Cobalt-60*** - The **gamma knife** is a highly specialized radiosurgery tool that uses multiple beams of **gamma radiation** to accurately treat targets in the brain or spine. - These beams are generated from approximately 201 individual sources of **Cobalt-60**, which emit high-energy photons focused on the target area, minimizing damage to surrounding healthy tissue. *I-131* - **Iodine-131** is primarily used in the treatment of **thyroid disorders**, such as hyperthyroidism and thyroid cancer, due to its ability to concentrate in thyroid tissue. - It emits both **beta particles** and **gamma rays**, but its primary therapeutic effect comes from the beta particles, not as a source for external beam radiation in radiosurgery. *P-32* - **Phosphorus-32** is a pure beta emitter with a relatively short range, making it suitable for certain **intracavitary or interstitial applications** in oncology. - It is utilized in conditions like **polycythemia vera** or for localized treatment of certain **cancers** but not as an external radiation source for gamma knife radiosurgery. *Strontium-89* - **Strontium-89** is a pure **beta emitter** used for **palliative treatment of bone pain** caused by metastatic bone disease. - It preferentially accumulates in areas of increased bone turnover and is not used as a radiation source for brain or spinal radiosurgery devices like the gamma knife.

Q: 'Gamma knife' is a term used to denote which of the methods of treatment?

Radiotherapy. ***Radiotherapy*** - The **gamma knife** is a highly precise form of **stereotactic radiosurgery** that delivers many small beams of gamma radiation to a target. - It is used to treat conditions like **brain tumors**, arteriovenous malformations, and trigeminal neuralgia without open surgery. *Chemotherapy* - **Chemotherapy** involves the use of drugs to destroy cancer cells, often affecting the entire body. - It does not involve focused radiation beams and is fundamentally different from a gamma knife. *Radioisotope scan* - A **radioisotope scan** (or nuclear scan) uses radioactive tracers to image the function and structure of organs. - It is a diagnostic imaging technique, not a method of treatment like the gamma knife. *Nuclear medicine* - **Nuclear medicine** is a branch of medicine dealing with the use of radioactive substances in diagnosis and treatment. - While gamma knife uses gamma radiation, the term nuclear medicine encompasses a broader range of diagnostic and therapeutic applications, and "gamma knife" specifically refers to a **radiotherapy technique**.

Q: Radiotherapy has the most significant therapeutic role in:

Sarcomas. ***Sarcomas*** - **Radiotherapy** plays a crucial therapeutic role in **sarcomas**, though typically as **adjuvant therapy** combined with surgical resection - Used for **local control** in soft tissue sarcomas, particularly when wide margins cannot be achieved - **Primary radiotherapy** is the treatment of choice for certain radiation-sensitive sarcomas like **Ewing's sarcoma** and in cases of **inoperable tumors** - Essential for reducing **local recurrence rates** in high-grade soft tissue sarcomas - Among the options listed, sarcomas have the **strongest and most established indication** for radiotherapy *Monoclonal gammopathy* - Generally **observation only** for MGUS (Monoclonal Gammopathy of Undetermined Significance) - Radiotherapy used only for **solitary plasmacytoma**, which is a specific localized manifestation - Multiple myeloma (if it progresses) is treated with **chemotherapy** and targeted agents, not radiotherapy as primary treatment *Tuberculosis* - An **infectious disease** caused by *Mycobacterium tuberculosis* - Treated exclusively with **anti-tubercular drug regimens** (RIPE: Rifampicin, Isoniazid, Pyrazinamide, Ethambutol) - Radiotherapy has **no role** in treating infections *Sarcoidosis* - A **systemic inflammatory condition** with non-caseating granulomas - Primary treatment is **corticosteroids** for symptomatic cases - Immunosuppressants used for refractory cases - Radiotherapy has **no role** in inflammatory/granulomatous diseases

Q: Which of the following radioactive isotopes is not used for brachytherapy?

Iodine-131. ***Iodine-131*** - **Iodine-131** is primarily used for **systemic radionuclide therapy** due to its emission of **beta particles** and **gamma rays**, making it suitable for treating diffuse diseases like **thyroid cancer** and **hyperthyroidism**. - Its mechanism of action relies on systemic uptake rather than localized placement within or next to a tumor, which defines **brachytherapy**. *Iodine-125* - **Iodine-125** is a common isotope used in **low-dose-rate (LDR) brachytherapy**, particularly for **prostate cancer** and **ocular melanoma**. - It emits **low-energy gamma and X-rays**, providing highly localized radiation with a steep dose fall-off, minimizing damage to surrounding healthy tissue. *Iridium-192* - **Iridium-192** is widely used in **high-dose-rate (HDR) brachytherapy** for various cancers, including **cervical**, **prostate**, **breast**, and **skin cancers**. - It emits **gamma rays** and has a shorter half-life than Iodine-125, allowing for higher dose rates over shorter treatment durations. *Cobalt-60* - **Cobalt-60** was historically used in **brachytherapy** and **teletherapy** but has largely been replaced by newer isotopes for brachytherapy due to its high energies and larger source size. - While its use in brachytherapy has decreased, it is still employed in specific applications and **external beam radiation therapy (teletherapy)**.

Q: A radioisotope used in both teletherapy and brachytherapy is

Cesium-137. ***Cesium-137*** - Cesium-137 is used in both **teletherapy (external beam radiation)** units, particularly older ones, and in **brachytherapy sources** for interstitial or intracavitary applications. - It emits **gamma rays** with an energy suitable for both types of therapy, giving it versatility. *Gold-198* - **Gold-198** is primarily used in **brachytherapy** as temporary or permanent implants, particularly for conditions like prostate cancer. - Its short half-life and primary emission of **beta particles** with accompanying gamma rays make it less suitable for external teletherapy applications. *Iodine-125* - **Iodine-125** is almost exclusively used in **low-dose-rate (LDR) brachytherapy**, commonly for prostate cancer and ocular melanomas. - It emits **low-energy gamma and X-rays**, which have a very limited range, making it unsuitable for teletherapy. *Radium-226* - **Radium-226** was historically one of the first radioisotopes used in brachytherapy but has largely been replaced due to its strong **gamma emissions** and the associated safety risks. - It was never widely adopted for teletherapy machines because its decay products include gaseous **radon**, posing significant handling and safety challenges.

Q: Classical indication of gamma knife amongst the following is:

Arterio-venous malformation. ***Arterio-venous malformation*** - Gamma Knife radiosurgery is a well-established and highly effective treatment for **intracranial arterio-venous malformations (AVMs)**, particularly those that are small to medium-sized and surgically inaccessible. - It works by delivering a highly focused dose of radiation to the abnormal blood vessels, causing them to gradually scar and occlude over time. *Hepatocellular carcinoma* - Gamma Knife radiosurgery is primarily designed and used for treating **intracranial lesions**, not peripheral solid organ tumors like hepatocellular carcinoma. - Treatment for hepatocellular carcinoma typically involves systemic therapies, surgical resection, or other localized interventions like transarterial chemoembolization (TACE) or radiofrequency ablation. *Tuberculoma* - Tuberculoma is an infectious granulomatous lesion, usually managed with **anti-tubercular drug therapy**. - Radiosurgery is not the primary treatment for infectious processes unless there's a specific indication for mass effect not responding to medical therapy, which is rare. *Glioblastoma* - While radiation therapy is a cornerstone of glioblastoma treatment, **Gamma Knife radiosurgery** is generally not a primary treatment for diffuse, infiltrative tumors like glioblastoma, especially at initial diagnosis. - It may be considered as an adjuvant or salvage therapy for small, recurrent lesions or focal recurrences, but its role is limited due to the infiltrative nature of the disease.

Question 1

Nowadays radium is not used in the Rx of cancer because:

Accepted Answer

It decays into daughter Radon which is a constant hazard

Answer

It is a very unstable element

Answer

It decays faster and needs frequent replacement

Answer

It has a very long half life

Question 2

Chronic radiation proctitis is associated with the treatment of all malignancies, EXCEPT:

Accepted Answer

Carcinoma small bowel

Answer

Carcinoma cervix

Answer

Carcinoma prostate

Answer

Carcinoma testes

Question 3

The ideal timing of radiotherapy for Wilms' tumor after surgery is -

Accepted Answer

Within 10 days

Answer

Any time after surgery

Answer

Within 2 months

Answer

Within 2 weeks

Question 4

Gamma knife utilizes -

Accepted Answer

Cobalt-60

Answer

1-131

Answer

P-32

Answer

Strontium 89

Question 5

'Gamma knife' is a term used to denote which of the methods of treatment?

Accepted Answer

Radiotherapy

Answer

Chemotherapy

Answer

Radioisotope scan

Answer

Nuclear medicine

Question 6

Intraoperative radiation therapy (IORT) is most commonly used in which of the following cancers?

Accepted Answer

Ca Pancreas

Answer

Ca Thyroid

Answer

Ca Cervix

Answer

Ca Breast

Question 7

Radiotherapy has the most significant therapeutic role in:

Accepted Answer

Sarcomas

Answer

Monoclonal gammopathy

Answer

Tuberculosis

Answer

Sarcoidosis

Question 8

Which of the following radioactive isotopes is not used for brachytherapy?

Accepted Answer

Iodine-131

Answer

Iodine-125

Answer

Iridium-192

Answer

Cobalt-60

Question 9

A radioisotope used in both teletherapy and brachytherapy is

Accepted Answer

Cesium-137

Answer

Gold-198

Answer

Iodine-125

Answer

Radium-226

Question 10

Classical indication of gamma knife amongst the following is:

Accepted Answer

Arterio-venous malformation

Answer

Hepatocellular carcinoma

Answer

Tuberculoma

Answer

Glioblastoma

Radiation Oncology Basics — MCQs

Radiation Oncology Basics — MCQs

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