AIMS: To quantify the changes in dose as well as in the prediction of parotid gland toxicity due to anatomical changes during therapy of head and neck cancer patients. MATERIALS AND METHODS: Fifteen patients with advanced locoregional head and neck cancer, with no evidence of distant metastasis, were enrolled in a prospective study. All patients were treated with intensity-modulated radiotherapy. Multiple computed tomography scans were repeated at the end of each treatment week. The original treatment plans were copied to the per-treatment scans to create hybrid plans. The normal tissue complication probability (NTCP) was calculated assuming the end point to be grade ≥3 xerostomia according to the Radiation Therapy Oncology Group late toxicity scale. RESULTS: The gross tumour volume dose coverage was slightly affected by the anatomical changes, whereas the mean dose (D(mean)) to the parotids changed from 26.1 ± 6.0 to 27.4 ± 7.4 Gy, with a mean increase of 0.22 Gy/treatment week. Consequently, the mean NTCP increased from 0.15 ± 0.06 to 0.18 ± 0.10, primarily due to a few patients exhibiting a marked increase. The absolute gross tumour volume shrinkage and the percentage parotids shrinkage were the best independent predictors for the NTCP variations. CONCLUSIONS: On average, the increase in the parotids D(mean) as well as in NTCP during treatment is limited, and the observed variations were strongly patient-dependent.
AIMS: To quantify the changes in dose as well as in the prediction of parotid gland toxicity due to anatomical changes during therapy of head and neck cancerpatients. MATERIALS AND METHODS: Fifteen patients with advanced locoregional head and neck cancer, with no evidence of distant metastasis, were enrolled in a prospective study. All patients were treated with intensity-modulated radiotherapy. Multiple computed tomography scans were repeated at the end of each treatment week. The original treatment plans were copied to the per-treatment scans to create hybrid plans. The normal tissue complication probability (NTCP) was calculated assuming the end point to be grade ≥3 xerostomia according to the Radiation Therapy Oncology Group late toxicity scale. RESULTS: The gross tumour volume dose coverage was slightly affected by the anatomical changes, whereas the mean dose (D(mean)) to the parotids changed from 26.1 ± 6.0 to 27.4 ± 7.4 Gy, with a mean increase of 0.22 Gy/treatment week. Consequently, the mean NTCP increased from 0.15 ± 0.06 to 0.18 ± 0.10, primarily due to a few patients exhibiting a marked increase. The absolute gross tumour volume shrinkage and the percentage parotids shrinkage were the best independent predictors for the NTCP variations. CONCLUSIONS: On average, the increase in the parotids D(mean) as well as in NTCP during treatment is limited, and the observed variations were strongly patient-dependent.
Authors: P L Yeap; D J Noble; K Harrison; A M Bates; N G Burnet; R Jena; M Romanchikova; M P F Sutcliffe; S J Thomas; G C Barnett; R J Benson; S J Jefferies; M A Parker Journal: Phys Med Biol Date: 2017-07-12 Impact factor: 3.609
Authors: S B Lim; C J Tsai; Y Yu; P Greer; T Fuangrod; K Hwang; S Fontenla; F Coffman; N Lee; D M Lovelock Journal: Technol Cancer Res Treat Date: 2019-01-01
Authors: Louise Belshaw; Christina E Agnew; Denise M Irvine; Keith P Rooney; Conor K McGarry Journal: Radiat Oncol Date: 2019-11-01 Impact factor: 3.481