How Low-Dose Radiation Therapy Works
A different kind of radiation than the one used for cancer. A much lower dose. A different goal. Here's the science — explained the way we'd explain it across a kitchen table.
Does this sound like you?
- You have a condition that keeps causing pain and inflammation
- Your body seems to stay in a constant state of irritation
- You've tried things — pills, injections, therapy — and the relief doesn't last
If that's familiar, the rest of this page explains why your pain may have become a self-sustaining problem, and what LDRT actually does to interrupt it.
Your immune system has two modes
Inside your body, certain immune cells called macrophages have two main settings — sometimes called M1 and M2. Both are normal. The problem is when one gets stuck.
M1 — attack mode
When you get hurt or sick, M1 cells take charge. They release inflammatory signals — TNF-α, IL-1, and IL-6 — that cause pain, swelling, and heat. These signals call in more fighter cells to handle the threat. In an acute injury, this is exactly what should happen.
M2 — healing mode
Once the threat is handled, M2 cells take over. They release IL-10 and TGF-β — calming signals that tell the immune system to slow down, repair tissue, and restore balance. M2 cells are your body's "off switch" for inflammation.
Why your pain won't go away
In chronic conditions — chronic plantar fasciitis, knee osteoarthritis, frozen shoulder, tennis elbow — the immune system gets stuck in M1. The fight signals stay elevated. The heal signals get drowned out. Your tissues keep getting damaged without a chance to repair.
The result: ongoing pain, swelling, and poor healing — your body is fighting itself instead of recovering.
Two very different uses of radiation
When most people hear "radiation," they think of cancer treatment. LDRT is a fundamentally different application of radiation. The dose, the goal, and the mechanism are all different.
Cancer radiation therapy
Cancer radiation therapy is designed to destroy diseased cells. The dose is high (typically 45–70 Gy), the goal is DNA damage, and side effects in surrounding tissue are an unavoidable trade-off.
Low-Dose Radiation Therapy (LDRT)
LDRT uses a 10–25× lower dose than cancer radiation. The goal is not to destroy cells but to change the signals they send — specifically, to nudge stuck M1 cells back toward the M2 healing state. The DNA stays intact. The cells stay alive. The biology changes.
Is LDRT safe?
- The dose used in LDRT is 10–25× lower than cancer radiation therapy.
- At these doses there is no tissue destruction and negligible DNA damage — well within the body's natural repair capacity.
- LDRT works with your body — it gently recalibrates the immune response rather than fighting against it.
- Think of it as a dimmer switch that turns down inflammation, not a weapon that destroys cells.
- LDRT for benign conditions has been used in Europe for decades with a well-characterized safety profile.
How LDRT actually works at the cellular level
LDRT works at the cellular level by changing how immune cells communicate. Specifically:
- Fewer fighter cells crowd in. Inflammatory cells stop sticking to blood vessel walls near the painful area, so fewer of them flood into the tissue.
- Less swelling at the source. Fewer inflammatory cells build up in the affected joint or tissue.
- Blood vessels calm down. The lining of your blood vessels stops sending out "come fight here" signals.
- Your body's signals rebalance. The chemical messengers shift from "keep fighting" to "start healing."
What patients can expect to feel
- Less pain as the "attack" signals calm down
- Less swelling as healing cells take over
- Better movement with less inflammation in the joint or tissue
- Healing restarts as your body's natural repair process gets back on track
These results come from restoring your body's balance — not from destroying tissue.
The simple version
"LDRT reduces key inflammatory signals like TNF-α and IL-1 while increasing healing signals like IL-10 — shifting the immune system from M1 (inflammation) to M2 (healing)."
In plain language:
- It turns down your body's "attack" signals that cause pain and swelling
- It turns up your body's natural "healing" signals that repair tissue
- Your immune cells shift from fighting to repairing
- Your immune system rebalances itself — naturally
Think of it as resetting your body's thermostat — not replacing it.
The bottom line
It's gentle
A much lower dose than cancer radiation — it works with your body, not against it.
It's targeted
Focused directly on the area causing your pain — telling those specific cells to switch from attacking to healing.
It restores balance
Your immune system gets stuck. LDRT helps reset it so your body can heal the way it's supposed to.
References
The mechanism summarized on this page is supported by the following peer-reviewed publications.
- Genard G, Lucas S, Michiels C. Reprogramming of tumor-associated macrophages with anticancer therapies: radiotherapy versus chemo- and immunotherapies. Front Immunol. 2017;8:828.
- Donaubauer AJ, et al. Low dose radiation therapy induces long-lasting reduction of pain and immune modulations in the peripheral blood (IMMO-LDRT01 trial). Front Immunol. 2021;12:740742.
- Deloch L, et al. Low-dose radiotherapy ameliorates advanced arthritis in hTNF-α tg mice by particularly positively impacting on bone metabolism. Front Immunol. 2018;9:1834.
- Riehl TE, et al. Low-dose radiation therapy (LDRT) in managing osteoarthritis: a comprehensive review. Semin Radiat Oncol. 2025 (in press).
- Deloch L, et al. Low-dose radiotherapy leads to a systemic anti-inflammatory shift and reduces osteoarthritic pain in patients. Front Immunol. 2022;12:803360.
- Frey B, et al. Low dose radiation, particularly with 0.5 Gy, improves pain in degenerative joint disease of the fingers. Cancers. 2020;12(10):2838.
- Genest L, et al. Low-dose irradiation differentially impacts macrophage phenotype in dependence of FLS and radiation dose. J Inflamm Res. 2019;12:69–83.
- Boustani J, et al. Low-dose radiation therapy (LDRT) against cancer and inflammatory or degenerative diseases: three parallel stories with a common molecular mechanism. Cancers. 2023;15(5):1438.
- Wunderlich R, et al. Modulation of inflammatory reactions by low-dose ionizing radiation: cytokine release of murine endothelial cells. Dose-Response. 2019;17(2).
- Kwon J, et al. Immune-modulatory effects of LDRT through macrophage polarization and transcriptional rewiring in triple-negative breast cancer. Biochem Biophys Res Commun. 2025 (in press).