Nidhin Das1, Sourabha Kumar Patro2, Darwin Kaushal3, Puneet Pareek4, Abhinav Dixit5, Sri Harsha Kombathula4, Kapil Soni1, Vidhu Sharma1, Amit Goyal6. 1. Department of Otorhinolaryngology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India. 2. Department of Otorhinolaryngology and Head and Neck Surgery, PGIMER, Chandigarh, India. 3. Department of Otorhinolaryngology, All India Institute of Medical Sciences, Himachal Pradesh, Bilaspur, India. 4. Department of Radiation Oncology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India. 5. Department of Physiology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India. 6. Department of Otorhinolaryngology, All India Institute of Medical Sciences, Jodhpur, Rajasthan, India. meetugoyal@yahoo.com.
Abstract
PURPOSE: This is a radiation field simulation study using CT images designed to see the cochlear dosimetry and its correlation with tumour and treatment characteristics during radiotherapy for head and neck cancers (HNC) for identifying the factors associated with a higher dose delivered to the cochlea. METHODS: From 2018 to 2020, 80 patients with HNC underwent volumetric arc therapy (VMAT) to a dose of 66-70 Gy at 2 Gy per fraction with bilateral cochlea contoured for VMAT optimization as an organ at risk. Minimum, mean and maximum planned radiation dose to the cochlea based on tumour and treatment characteristics and dose-volume histogram variables of VMAT plans were analysed. RESULTS: Mean (standard deviation, SD) cochlear volume was 0.14 (0.06) cm3 with maximum and mean planned doses of 10.3 (SD = 11.6) Gy and 8.5 (SD = 9.8) Gy, respectively. We found a statistically significant correlation between mean dose received by bilateral cochlea (P-0.000, rright-0.84, rleft-0.78, rmidline-0.92). Tumours of the paranasal sinuses, and the parotids and more advanced T stages were associated with a higher mean dose to cochlea but was not significant statistically. The dose received by the 95% target nodal volume (D95%) showed a significant correlation with the cochlear mean dose (P-0.000, rright-0.85, rleft-0.77, rmidline-0.93) CONCLUSION: With VMAT we have achieved a better sparing of cochlea. The mean dose to the cochlea of one side significantly differed from the other side in patients with lateralized cancers. D95% of nodal volume also showed a significant correlation with the cochlear mean dose.
PURPOSE: This is a radiation field simulation study using CT images designed to see the cochlear dosimetry and its correlation with tumour and treatment characteristics during radiotherapy for head and neck cancers (HNC) for identifying the factors associated with a higher dose delivered to the cochlea. METHODS: From 2018 to 2020, 80 patients with HNC underwent volumetric arc therapy (VMAT) to a dose of 66-70 Gy at 2 Gy per fraction with bilateral cochlea contoured for VMAT optimization as an organ at risk. Minimum, mean and maximum planned radiation dose to the cochlea based on tumour and treatment characteristics and dose-volume histogram variables of VMAT plans were analysed. RESULTS: Mean (standard deviation, SD) cochlear volume was 0.14 (0.06) cm3 with maximum and mean planned doses of 10.3 (SD = 11.6) Gy and 8.5 (SD = 9.8) Gy, respectively. We found a statistically significant correlation between mean dose received by bilateral cochlea (P-0.000, rright-0.84, rleft-0.78, rmidline-0.92). Tumours of the paranasal sinuses, and the parotids and more advanced T stages were associated with a higher mean dose to cochlea but was not significant statistically. The dose received by the 95% target nodal volume (D95%) showed a significant correlation with the cochlear mean dose (P-0.000, rright-0.85, rleft-0.77, rmidline-0.93) CONCLUSION: With VMAT we have achieved a better sparing of cochlea. The mean dose to the cochlea of one side significantly differed from the other side in patients with lateralized cancers. D95% of nodal volume also showed a significant correlation with the cochlear mean dose.
Authors: L Brugieres; O Hartmann; E Benhamou; E S Zafrani; J M Caillaud; C Patte; C Kalifa; F Flamant; J Lemerle Journal: Bone Marrow Transplant Date: 1988-01 Impact factor: 5.483