I had SBRT in 2018 for a bone metastasis on my left femur. It was targeted and mappeds out with a CT/PET scan.
My radiation oncologist told me that he recommended a single higher radiation dose over having several doses at a lower Gray (Gy). Based on his recommendation and my own ignorance on this topic, I agreed. It worked to kill the cancer lesion and my pain almost un noticable.
2 years later, a sprained by left ankle badly running for a light rail to work. I attended to it, expecting to recover from it quickly. Instead, I had series of these sprains occur. I went to a podiatrist who recommended I get a nerve conductivity test because she thought it might be neurological. The test confirmed this I had nerve damage to my peroneal nerve running down the outside of my leg to my foot.
Ultimately, I was diagnosed by a neurologist with "foot drop". This is a progressive loss of motor control of the foot (paralyzation) and my need for a rigid leg/foot brace. The pain in my left lower leg and foot was extreme and unpredictable. It disturbed my sleep and my mobility. I was forced to quit work and to go onto SS Disability, a major loss of income and of a career I enjoyed. However, it was the right choice for me.
Bottom line is that I believe the high dose of radiation, while it was likely on target for the lesion, penetrated the bone and caught the nerve as well. It may have been in the fine print for the release I signed before having the therapy but it was not discussed as potential side effect. After the fact, I was told that this happen sometimes and is not uncommon for some percentage of patients to have nerve damage. Whether it was operator error or a mistake my RO made, it is done and it is permanent. It greatly limits my activities and makes it much harder to exercise.
I recommend that anyone considering radiation therapy to do their homework about benefits and side effects of the proposed treatment before moving ahead. I also recommend pressing the RO about possible side effects and their incidence, as a percentage of patients treated. If you don't get straight answers go to an RO who will provide the answers to your questions.