## Core Concept
The question pertains to the application of radioisotopes in the management of painful bone metastases. Radioisotopes are used for their localized radiation effects, providing palliative relief from pain in patients with metastatic bone disease.

## Why the Correct Answer is Right
Strontium-89 (Sr-89) and Samarium-153 (Sm-153) are well-known radioisotopes used for the treatment of painful bone metastases. They work by being taken up in areas of bone turnover, thereby delivering localized radiation that helps in reducing pain. Phosphorus-32 (P-32) is primarily used for certain hematologic disorders and not commonly for bone pain palliation. Radium-223 (Ra-223) is specifically used for the treatment of bone metastases from prostate cancer, providing a targeted approach to alleviate pain and delay skeletal events.

## Why Each Wrong Option is Incorrect
- **Option A:** Sr-89 is indeed used for treating painful bone metastases, making it an incorrect choice as an exception.
- **Option C:** Sm-153 is also used for similar purposes, providing relief from bone pain in metastatic disease, which makes it incorrect as an exception.
- **Option D:** Ra-223 is specifically approved for the treatment of bone metastases in prostate cancer patients, making it incorrect as an exception.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while these radioisotopes offer palliative benefits for patients with bone metastases, their use is often considered when other treatments like external beam radiation therapy, opioids, and bisphosphonates are insufficient or not feasible. Each radioisotope has specific indications and side effect profiles.

## Correct Answer: B.