Dosimetric and radiobiological comparison of IMRT, VMAT, and helical tomotherapy planning techniques in hippocampal sparing whole brain radiotherapy with simultaneous integrated boost for multiple brain metastases.

To compare treatment planning and dosimetric outcomes for hippocampal sparing whole brain radiotherapy (WBRT) with the simultaneous integrated boost (SIB) in brain metastasis (BM) patients using tumour control probability (TCP) and normal tissue complication probability (NTCP) formalism between IMRT, VMAT, and HT techniques. In this retrospective study, the treatment data of 20 BM patients who typically received whole brain radiation with SIB treatment were used. Prescription doses of 30 Gy and 36 Gy was delivered in 10 fractions for WBRT and SIB, respectively. Niemierko and LKB models were applied for calculating TCP and NTCP. All the plans were evaluated for the RTOG 0933 protocol criteria and found acceptable. Additionally, the homogeneity of the PTV boost is 0.07 ± 0.01, 0.1 ± 0.04, and 0.08 ± 0.02 for IMRT, VMAT, and HT, respectively (P < 0.05). The percentage of TCP for the PTV boost was 99.99 ± 0.003, 99.98 ± 0.004, and 99.99 ± 0.002 of IMRT, VMAT, and HT, respectively, (P < 0.005). The NTCP value of the lenses was higher with the VMAT plan as compared to IMRT and HT Plans. The hippocampal NTCP values are equal in all three planning proficiencies. The techniques like IMRT, VMAT, and HT can reduce the dose received by hippocampus to the dosimetric threshold during the delivery of WBRT with hippocampal sparing and can simultaneously boost multiple metastases. Overall, the high-quality dose distribution, TCP, and NTCP comparison between all three planning techniques show that the HT technique has better results when compared to the VMAT and IMRT techniques.

A Dosimetric and Radiobiological Comparison of Intensity Modulated Radiotherapy, Volumetric Modulated Arc Therapy and Helical Tomotherapy Planning Techniques in Synchronous Bilateral Breast Cancer.

OBJECTIVE: The present investigation intends to identify the optimal radiotherapy treatment plan for synchronous bilateral breast cancer (SBBC) using dosimetric and radiobiological indexes for three techniques, namely, helical tomotherapy (HT), volumetric modulated arc therapy (VMAT), and intensity-modulated radiotherapy (IMRT). METHODS: Twenty SBBC treated female patients treatment planning data (average age of 52.5 years) were used as the sample for the present study. Three different plans were created using 50 Gy in a 25 fraction dose regime. Poisson, Niemierko, and LKB models were applied for calculating normal tissue complication probability (NTCP) and tumour control probability (TCP). RESULT: The target average dose comparison between IMRT with HT and VMAT with HT was highly substantial (P=0.001). The percentage of TCP for IMRT, VMAT, and HT in the Poisson model were 93.70±0.28, 94.68±0.30, and 94.34±0.57, respectively (p<0.05). The dose maximum was lower for the whole lung in the HT plan, with an average dose of 49.31Gy±3.9 (p<0.009). The NTCP values of both Niemierko and LKB models were lower for the heart, lungs, and liver for the IMRT plan. CONCLUSION: The sparing of organs at risk was higher in the HT plan dosimetrically, and the TCP was higher in the three techniques. The comparison between the three techniques shows that the IMRT and HT techniques could be considered for treating SBBC.

Pediatric Craniospinal Irradiation - The implementation and Use of Normal Tissue Complication Probability in Comparing Photon versus Proton Planning.

Purpose: The preferred radiotherapy treatment for medulloblastoma is craniospinal irradiation (CSI). With the aim of developing the potential to reduce normal tissue dose and associated post-treatment complications with photon and proton radiotherapy techniques for CSI. This report aims to carefully compare and rank treatment planning and dosimetric outcomes for pediatric medulloblastoma patients using normal tissue complication probability (NTCP) formalism between photon (three-dimensional conformal radiotherapy, intensity-modulated radiotherapy [IMRT], volumetric-modulated arc therapy [VMAT], and HT) and proton CSI. Methods and Materials: The treatment data of eight pediatric patients who typically received CSI treatment were used in this study. The patients were 7 years of age on average, with ages ranging from 3 to 11 years. A prescription dose of 3600 cGy was delivered in 20 fractions by the established planning methods. The Niemierko's and Lyman-Kutcher-Burman models were followed to carefully estimate NTCP and compare different treatment plans. Results: The NTCP of VMAT plans in upper and middle thoracic volumes was relatively high compared to helical tomotherapy (HT) and pencil beam scanning (PBS) (all P < 0.05). PBS rather than IMRT and VMAT in the middle thoracic region (P < 0.06) could significantly reduce the NTCP of the heart. PBS significantly reduced NTCP of the lungs and liver (all P < 0.05). Conclusion: The NTCP and tumor control probability (TCP) model-based plan ranking along with dosimetric indices will help the clinical practitioner or medical physicists to choose the best treatment plan for each patient based on their anatomical or clinical challenges.

Yttrium-doped cobalt nanoferrites prepared by sol-gel combustion method and its characterization.

Ferrites are extremely important magnetic ceramics in the production of electronic components because they reduce the energy losses by the induced currents acting as electrical insulators. Similarly, the spinel-structured cobalt-based ferrites are promising materials for stress, torsion sensors and energy storage applications (anode materials in lithium batteries, fuel cells and solar cells). Therefore, many studies have focused on cobalt ferrites obtained using conventional techniques. Different sintering conditions, types and levels of substitution result in different microstructures and magnetostriction coefficients under a wide range of preparation conditions. Despite many attempts, there are no specific reports on the trivalent substitution of yttrium in cobalt ferrite to the best of our knowledge. In the present study, yttrium-doped cobalt ferrite was prepared with different concentrations to identify the crystallite size with respect to the yttrium concentration, temperature and changes in the structural and electrical properties. In addition, the resistance of the nanostructured yttrium-doped cobalt ferrites nanopowders was analyzed. The resistance was increased by the addition of yttrium to cobalt ferrites.