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1.
Indian J Cancer ; 2023 Mar; 60(1): 140-147
Article | IMSEAR | ID: sea-221768

Résumé

Background: Adaptive radiation therapy (ART) refers to redesigning of radiation therapy (RT) treatment plans with respect to dynamic changes in tumor size and location throughout the treatment course. In this study, we performed a comparative volumetric and dosimetric analysis to investigate the impact of ART for patients with limited-stage small cell lung cancer (LS-SCLC). Methods: Twenty-four patients with LS-SCLC receiving ART and concomitant chemotherapy were included in the study. ART was performed by replanning of patients based on a mid-treatment computed tomography (CT)-simulation which was routinely scheduled for all patients 20� days after the initial CT-simulation. While the first 15 RT fractions were planned using the initial CT-simulation images, the latter 15 RT fractions were planned using the mid-treatment CT-simulation images acquired 20� days after the initial CT-simulation. In order to document the impact of ART, target and critical organ dose-volume parameters acquired from this adaptive radiation treatment planning (RTP) were compared with the RTP based solely on the initial CT-simulation to deliver the whole RT dose of 60 Gy. Results: Statistically significant reduction was detected in gross tumor volume (GTV) and planning target volume (PTV) during the conventionally fractionated RT course along with statistically significant reduction in critical organ doses with incorporation of ART. Conclusion: One-third of the patients in our study who were otherwise ineligible for curative intent RT due to violation of critical organ dose constraints could be treat

2.
Indian J Cancer ; 2022 Sep; 59(3): 402-407
Article | IMSEAR | ID: sea-221708

Résumé

Background: The aim of our study is to assess the dose enhancement from scattered radiation due to dental restorative materials used for occlusal and mesio-occlusal-distal (MOD) cavity filling during simulated head and neck radiotherapy. Methods: We have studied the dose enhancement ratio (DER) of conventional amalgam, high-copper amalgam, and resin composite dental restorative materials at cadaver mandible teeth using 2 therapeutic photon energies of 1.25 MeV (Co-60 gamma ray) and 6 MV (Linac X-ray) for irradiation. Results: DER values at buccal position for Co-60 and 6 MV X-ray were 1.250 ± 0.013 and 1.151 ± 0.012, respectively. For dental cavity fillings, DER values for 6 MV X-ray were 1.065 ± 0.021, 1.100 ± 0.014, and 1.162 ± 0.016 for resin composite filling, low-copper amalgam filling, and high-copper amalgam filling, respectively. Our results revealed that DER regarding irradiation energy was minimum for 6 MV X-rays. With respect to dental restorative filling material, DER was minimum for resin composite filling. Regarding the cavity type, our results with standard deviation (SD) calculations revealed that DER was slightly but not significantly different for both Co-60 gamma ray (1.25 MeV) and 6 MV X-ray energies for both occlusal and MOD cavities. Conclusion: Our dosimetric results for a single beam geometry suggest that, among the three types of filling, resin composite filling is an ideal restorative filling material with minimal morbidity-inducing radiation dose enhancement that may result in increased osteoradionecrosis and secondary caries risk. There is a need for further dosimetric studies with actual clinical beam arrangements.

3.
Indian J Cancer ; 2018 Apr; 56(2): 151-156
Article | IMSEAR | ID: sea-190220

Résumé

AIMS AND BACKGROUND: There is scant data on the utility of repeated radiosurgery for management of locally recurrent brain metastases after upfront stereotactic radiosurgery (SRS). Most studies have used single-fraction SRS for repeated radiosurgery, and the use of fractionated stereotactic radiosurgery (f-SRS) in this setting has been poorly addressed. In this study, we assessed the utility of f-SRS for the management of locally recurrent brain metastases after failed upfront single-fraction SRS and report our single-center experience. METHODS AND STUDY DESIGN: A total of 30 patients receiving f-SRS for locally recurrent brain metastases after upfront single-fraction SRS at our department between September 2011 and September 2017 were retrospectively evaluated for local control (LC), toxicity, and overall survival outcomes. RESULTS: Median age and Karnofsky performance status were 57 (range: 38–78 years) and 80 (range: 70–100) at repeated radiosurgery (SRS2). The median time interval between the two radiosurgery applications was 13.5 months (range: 3.7–49 months). LC after SRS2 was 83.3%. Radionecrosis developed in 4 of the 30 lesions after SRS2, and total rate of radionecrosis was 13.3%. Statistical analysis revealed that the volume of planning target volume (PTV) at SRS2 was significantly associated with radionecrosis (P = 0.014). The volume of PTV was >13 cm3 at SRS2 in all patients with radionecrosis. CONCLUSION: A repeated course of radiosurgery in the form of f-SRS may be a viable therapeutic option for the management of locally recurrent brain metastases after failed upfront SRS with high LC rates and an acceptable toxicity profile despite the need for further supporting evidence.

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