Radiation Therapy
Intensity-Modulated Radiation Therapy (IMRT)
Dose Reduction to Cochlea: IMRT is designed to spare organs at risk by modulating radiation beams more precisely than conventional techniques. Studies have demonstrated modest radiation-induced hearing deterioration with IMRT, such as a 1.5 dB loss at speech frequencies and 2.7 dB at ultra-high frequencie
Proton Radiation Therapy (PRT)
Precision and Cochlear Sparing: Proton therapy delivers radiation with high precision and has a finite beam length, which minimizes radiation exposure to surrounding healthy tissues, including the cochlea. This characteristic makes PRT advantageous for hearing preservation in some cases[1][4].
Risk of Hearing Loss: Desp
In summary, the likelihood and severity of hearing loss increase significantly with higher radiation doses, particularly when exceeding 50 Gy to auditory structures. Regular audiometric monitoring during and after treatment is essential for early detection and management.
Conductive hearing loss may occur at high doses due to middle ear complications such as otitis media or fibrosis, but SNHL is more common and dose-dependent
Thresholds for Hearing Loss:
A study found that the probability of SNHL increases sharply when the cochlea receives doses above 48 Gy, with a steeper dose-response curve for older patients or those with pre-existing hearing issues[3].
For nasopharyngeal cancer patients treated with doses between 63–70 Gy, significant hearing loss was observed within
Moderate to High-Dose Radiation:
Sensorineural hearing loss (SNHL) becomes more prevalent with higher doses. Doses exceeding 50 Gy to the cochlea are strongly associated with significant SNHL, often characterized by a ≥15 dB threshold shift across multiple frequencies[3].
High doses (>60 Gy) can cause permanent damage to the sensory hair cells, co
Low-Dose Radiation:
Even low-dose radiation can affect hearing, but the impact is generally less severe compared to high doses. Studies show that individuals exposed to low-dose radiation may experience subtle changes in hearing thresholds, particularly at high frequencies (e.g., 4-16 kHz) due to vascular or cochlear changes[1].
Middle ear function i
While some cases of radiation-induced conductive hearing loss may improve over time, others—especially those involving fibrosis or ossicular damage—can result in long-term or permanent hearing impairment
Nasopharyngeal cancer patients are particularly at risk due to radiation targeting areas close to the ET and middle ear[