Point A in radiotherapy for Ca cervix corresponds to
**Core Concept**
Point A in radiotherapy for cervical cancer is a critical target volume defined by the International Brachytherapy Working Group (IWG). It represents a specific dose point that ensures adequate coverage of the tumor and the obturator lymph nodes, while minimizing exposure to surrounding tissues.
**Why the Correct Answer is Right**
The Point A dose is prescribed to an isodose line that covers at least 70% of the high-risk clinical target volume (HR-CTV), which includes the primary tumor and the obturator lymph nodes. This dose point is typically set at 85-90 Gy to the point A, considering the ICRU 38 recommendations. The point A is usually located 2 cm lateral to the cervical canal and 2 cm superior to the external os.
**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not correspond to the definition of Point A in radiotherapy for cervical cancer.
**Option B:** Incorrect because it is not a standard nomenclature for dose points in cervical cancer brachytherapy.
**Option C:** Incorrect because it is not the correct anatomical location of Point A.
**Clinical Pearl / High-Yield Fact**
When prescribing dose to Point A, it is essential to consider the ICRU 38 recommendations and the individual patient's anatomy to ensure optimal tumor coverage and minimize side effects.
**Correct Answer: D. Point A in radiotherapy for cervical cancer corresponds to a dose point 2 cm lateral to the cervical canal and 2 cm superior to the external os.**