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Introduction and Objective: Anatomic and volumetric changes occur in head-and-neck cancer during fractionated radiotherapy (RT), and the actual dose received by patient is considerably different from the original plan. The purpose of this study is to evaluate volumetric and dosimetric changes occurring during radiation therapy. Patients and Methods: Ten patients of locally advanced head-and-neck cancer, 6 oropharynx, 3 larynx, and 1 hypopharynx underwent computed tomography (CT) simulation before treatment and after 4 weeks during RT treatment. Original plan (OPLAN) was generated based on initial CT scan for the entire course of treatment. The initial plan is implemented on the second planning CT scan, and the dose distribution is recalculated. Beam configuration of OPLAN was applied onto the second CT scan and then hybrid plan (HPLAN30) was generated. RPLAN30 is the intensity-modulated RT replan generated on the second CT scan for the remaining 30 Gy. Dose and volume parameters between OPLAN30 (based on the first CT scan for the remaining 30 Gy), HPLAN30, and RPLAN30 were compared. Results: The volume reduction of planning target volume (PTV), ipsilateral and contralateral parotid after 4 weeks of RT, was statistically significant (P < 0.05). D2% and V > 107% of PTV were higher in HPLAN than that of RPLAN (P < 0.05). Hybrid plans showed increase in delivered dose to spinal cord. Mid treatment replanning reduced doses to spinal cord (Dmax and D1%), which is statistically significant (P < 0.05). Mean doses to ipsilateral and contralateral parotid of RPLAN (21.4 Gy and 16.74 Gy, respectively) were reduced when compared to that of HPLAN (22.99 Gy and 22 Gy, respectively). Conclusion: Interim CT scanning and replanning (adaptive) improves target volume coverage and normal tissue sparing
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Objective: In this study we evaluated the prognostic factors, dosimetry and survival outcome of high grade gliomas receiving radiotherapy with concurrent temozolomide and with or without adjuvant temozolomide. Materials and Methods: Eighty patients with high grade gliomas were treated with concurrent chemoradiation post operatively. 27 patients received 3D Conformal Radiotherapy, 25 received Intensity Modulated Radiotherapy and 28 were treated with Rapid arc. Temozolomide 75mg/m2/d seven days a week was given concurrently with radiation (60Gy in 30 fractions) followed by 6 cycles of adjuvant Temozolomide with a dose of 150mg/m2/d for 5 days in every 28 days. Primary end point was overall survival and secondary end point was effect of radiation technique on overall survival and dose to organs at risk. Results: All patients completed concurrent chemoradiation but only 52 patients completed 6 months course of adjuvant chemotherapy. Median age was 52.5 years; The prognostic factors important for overall survival are at least 6 cycles of adjuvant temozolomide (p<0.0001) and mean dose to normal brain <30 Gy (p-0.022). Median overall survival was 6 months. The median survival for patients who completed 6 months of adjuvant chemotherapy and those who did not was 12 months and 3 months respectively. Survival at 12, 18 and 24 months were 24.5%, 13.2% and 11.3% respectively for patients treated with high precision radiotherapy. One year survival in 3DCRT group was 3.7%. Mean dose to normal brain was 28.7Gy in 3DCRT, 23.9Gy in high precision technique respectively. Conclusion: Reduced doses to normal brain with high precision techniques and improved survival in our patients receiving radiotherapy with concurrent temozolomide & adjuvant 6 cycles of temozolomide.