The Critical Role of Skin Sensitization Testing in Radiotherapy Equipment
Patient positioning are essential in modern radiotherapy, ensuring accurate dose delivery, minimizing exposure to healthy tissues and enhancing treatment reproducibility. However, these devices come in direct contact with the patient’s skin, often for prolonged durations. This makes biocompatibility testing a critical component in product development and validation.
In radiotherapy positioning systems come into direct contact with a patient’s skin, often for extended sessions across multiple fractions. To ensure their safe clinical use, materials used in these devices must undergo biological evaluation for potential dermal irritation.
Panacea Medical Technologies conducted an evaluation of its carbon fiber material, used in patient positioning boards that come in direct contact with patients, to confirm its non-sensitizing nature at a NABL-accredited test laboratory.
Testing facility: GLR Laboratories Private Limited
This summary presents findings from a skin irritation study on a carbon fiber sheet intended for use in external patient-contact components of radiotherapy systems.
Objective
To evaluate the cutaneous irritation potential of the test item using polar and non-polar solvent extracts, as per the elution method described in ISO 10993-10:2020(E).
Study Design Summary
- Test System: Female New Zealand White Rabbits (n=3)
- Extracts Prepared In:
- Polar solvent: Physiological saline
- Non-polar solvent: Sesame oil
- Extraction Ratio: 3 cm²/mL
- Extraction Conditions: 50 °C for 72 hours
- Application Area: 6 cm² on clipped dorsal skin
- Exposure Duration: 24 hours under semi-occlusive dressing
- Assessment Intervals: 1, 24, 48, and 72 hours post removal
- Evaluation Criteria: Erythema and edema scoring based on ISO grading scale
Results
- Visual Observation:
- No erythema or edema was observed at any evaluation time point (1h, 24h, 48h, 72h)
- No skin abnormalities or reactions in any of the test or control sites
- Animal Health:
- No signs of distress, systemic illness, or mortality
- All animals gained weight during the observation period
- Primary Irritation Index (PII):
- Calculated as 0.00 for both polar and non-polar extracts
- According to ISO 10993-10 classification, the material is considered non-irritant
- Assay Validity:
- Positive control (Sodium Lauryl Sulfate) in separate study produced expected reaction
- Extraction vehicles remained stable and unchanged in clarity and pH
Conclusion
Based on the study conducted in accordance with ISO 10993-10:2020(E), the carbon fiber sheet extract demonstrated no evidence of skin irritation under the test conditions. It is classified as non-irritant, supporting its safe use in patient-contact immobilization devices for radiotherapy.
Relevance to Clinical Use
The absence of skin irritation is a critical factor in materials used in radiotherapy positioning systems, where repeated skin contact is expected across treatment fractions. This study confirms that the tested material:
- Presents no dermal risk to patients under routine clinical exposure
- Complies with international standards for biocompatibility
- Supports patient safety and comfort during prolonged use
“Every design is backed by data, so clinicians can focus on what matters most—treating patients with precision and care.”