Image-Guided Superficial Radiation Therapy (IG-SRT) is a non-surgical approach to treating non-melanoma skin cancers, such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). It works by delivering a beam of low-energy X-rays directly to the cancerous cells. The treatment targets the lesion without requiring any cutting.
Understanding the Technology
Image-Guided Superficial Radiation Therapy is a technological advancement built on the foundation of Superficial Radiation Therapy (SRT). The “Superficial Radiation Therapy” component uses low-energy X-rays, similar in energy to those used for dental X-rays, to treat the skin cancer. These photons have a limited penetration depth, typically reaching only about 2 to 7 millimeters into the skin. This shallow penetration is intentional, as it ensures the radiation dose is concentrated on the surface tumor while minimizing exposure to the deeper, healthy tissues. The low-energy X-rays destroy the cancer cells by damaging their DNA, preventing them from multiplying and causing them to die.
The “Image-Guided” aspect distinguishes IG-SRT from older radiation techniques. This guidance is achieved using high-resolution dermal ultrasound (HRDUS) technology, which operates at a high frequency to create clear images of the skin layers. Before each treatment session, the ultrasound is used to precisely map the tumor’s size, shape, and depth beneath the skin’s surface. This visualization ensures that the radiation beam is accurately targeted to cover the entire cancerous area, which can extend beyond what is visible to the naked eye.
Imaging the tumor before every session allows the medical team to make adaptive adjustments to the radiation energy and dose, tailoring the treatment plan as the tumor responds and shrinks. This high-level precision and ability to measure tumor depth results in improved local control compared to non-image-guided SRT. The imaging also confirms that the prescribed radiation dose is fully encompassing the tumor, monitored through the 90% isodose line.
The Treatment Process
IG-SRT is typically performed in an outpatient setting. The treatment schedule is fractionated, meaning the total dose of radiation is broken up into multiple small doses delivered over several weeks. A common protocol involves receiving sessions three to five times per week, for a total of approximately 20 to 30 sessions over four to seven weeks.
During a typical appointment, the patient is positioned comfortably while the treatment site is prepared. A high-resolution ultrasound is performed first to confirm the exact boundaries and depth of the tumor. The radiation therapist then places an applicator cone over the treatment area to direct the low-energy X-ray beam.
The radiation delivery is quick and painless, lasting about 90 seconds to a few minutes. Because the procedure is non-invasive and does not require anesthesia, patients remain awake and can resume their normal daily activities immediately after leaving the clinic. This lack of downtime is a significant advantage for patients who wish to maintain their regular schedule throughout the course of treatment.
Effectiveness and Expected Results
IG-SRT is a highly effective treatment for non-melanoma skin cancers, with cure rates exceeding 99% for both basal cell and squamous cell carcinomas. This efficacy is comparable to surgical options for early-stage lesions. The high success rate is attributed to the image-guidance, which ensures the entire tumor is precisely targeted with the curative radiation dose.
Since the treatment avoids cutting and stitches, the risk of significant scarring is minimized, often leading to better cosmetic outcomes than traditional surgical excision. Acute side effects are temporary and confined to the treated area, resolving after the treatment course is complete. Common reactions include mild redness, irritation, dryness, or peeling of the skin, similar to a sunburn. Temporary hair loss may also occur.
IG-SRT is recommended for patients with lesions in cosmetically sensitive areas, such as the nose, ears, eyelids, or lips, where surgery could lead to disfigurement or complex reconstruction. It is also an option for elderly patients or those with coexisting medical conditions, like a bleeding disorder, who may not be candidates for surgery. The non-invasive nature and high cure rate make it a preferred alternative for individuals seeking a non-surgical approach to their skin cancer treatment.