**Core Concept**
Intraoperative radiotherapy (IORT) is a technique that delivers high doses of radiation directly to the tumor site during surgery, minimizing damage to surrounding healthy tissues. It is particularly useful in treating pancreatic carcinoma, a highly aggressive and locally advanced cancer.

**Why the Correct Answer is Right**
Electron beam radiation is the primary choice for IORT in pancreatic carcinoma due to its ability to deliver precise and conformal doses of radiation to the tumor site, while sparing the surrounding tissues. The electron beam has a finite range, which allows it to be stopped at a specific depth, reducing the risk of damage to adjacent organs. This is particularly important in pancreatic surgery, where the tumor is often in close proximity to critical structures such as the duodenum, stomach, and major blood vessels.

**Why Each Wrong Option is Incorrect**
**Option A:** Alpha Rays are high-energy particles that have a short range and can cause significant damage to surrounding tissues, making them unsuitable for IORT.
**Option B:** Gamma Rays have a long range and can be difficult to control, increasing the risk of damage to adjacent organs and making them less suitable for IORT.
**Option D:** Proton beam radiation is a type of particle therapy that can be effective for certain types of cancer, but it is not typically used for IORT due to its limited availability and higher cost compared to electron beam radiation.

**Clinical Pearl / High-Yield Fact**
When planning IORT for pancreatic carcinoma, it is essential to carefully select the electron beam energy and beam size to ensure that the tumor is adequately covered while minimizing the risk of damage to surrounding tissues. A general rule of thumb is to use a beam energy of 10-12 MeV for pancreatic tumors, which provides a good balance between tumor coverage and tissue sparing.

**✓ Correct Answer: C. Electron Beam**