Radiation therapy services during the COVID-19 pandemic

Relevance: The outbreak of a new respiratory disease SARS CoV-2 (COVID-19), reported by China in December 2019, significantly impacted cancer treatment. However, modern radiotherapy techniques remain in use during the COVID-19 pandemics. They include intensive modulated radiation therapy (IMRT, VMAT), image-guided radiation therapy (IGRT), stereotactic radiosurgery, and radiotherapy (SRS and SRT). The research aimed to compare the techniques used and the throughput of the linear accelerator before and during the COVID-19 pandemics. Results: The results were measured during nine months of operation of Almaty Oncology Center before the pandemic (April-December 2019) and the similar period during the pandemic in 2020. The amount of high-tech radiotherapy services provided before and during the COVID-19 pandemic equaled to (amount of sessions/ number of patients): conformal (3D) radiotherapy – 6510/335 vs. 6005/286; IGRT – 9171/524 and 8977/551; IMRT and VMAT – 4208/190 vs. 5992/287. The share of more complex methods of radiation therapy (IMRT, VMAT) has increased from 39.3% of sessions before the COVID-19 pandemic to 49.9% during the pandemic. The number of SRS and SRT procedures performed/patients served has also increased from 14/6 to 47/13. The average amount of services per patient before and during the COVID-19 pandemic has changed as follows: conformal radiation therapy – from 19.4 sessions to 21.0, IMRT and VMAT – from 22.1 to 20.9, IGRT – from 17.5 to 16.3. Conclusion: During the COVID-19 pandemic, there was no decrease in the amount of radiotherapy services provided; the use of more high-tech radiotherapy techniques has increased 1.4 times.

Radiation therapy services during the COVID-19 pandemic

Relevance: The outbreak of a new respiratory disease SARS CoV-2 (COVID-19), reported by China in December 2019, significantly impacted cancer treatment. However, modern radiotherapy techniques remain in use during the COVID-19 pandemics. They include intensive modulated radiation therapy (IMRT, VMAT), image-guided radiation therapy (IGRT), stereotactic radiosurgery, and radiotherapy (SRS and SRT). The research aimed to compare the techniques used and the throughput of the linear accelerator before and during the COVID-19 pandemics. Results: The results were measured during nine months of operation of Almaty Oncology Center before the pandemic (April-December 2019) and the similar period during the pandemic in 2020. The amount of high-tech radiotherapy services provided before and during the COVID-19 pandemic equaled to (amount of sessions/ number of patients): conformal (3D) radiotherapy – 6510/335 vs. 6005/286; IGRT – 9171/524 and 8977/551; IMRT and VMAT – 4208/190 vs. 5992/287. The share of more complex methods of radiation therapy (IMRT, VMAT) has increased from 39.3% of sessions before the COVID-19 pandemic to 49.9% during the pandemic. The number of SRS and SRT procedures performed/patients served has also increased from 14/6 to 47/13. The average amount of services per patient before and during the COVID-19 pandemic has changed as follows: conformal radiation therapy – from 19.4 sessions to 21.0, IMRT and VMAT – from 22.1 to 20.9, IGRT – from 17.5 to 16.3. Conclusion: During the COVID-19 pandemic, there was no decrease in the amount of radiotherapy services; the use of more high-tech radiotherapy techniques has increased 1.4 times.

A Simulation of a Novel High Quantum Efficiency Scintillating Fiber Detector with Anti-scatter Properties for Megavoltage X-Ray Imaging

To further develop a MV x-ray portal imaging device with high detection efficiency and adequate spatial resolution for image guided radiation therapy, the experimental results for a prototype detector were matched using Monte-Carlo software to then improve upon the design. The simulation and experiment were carried out using a 6 MV beam from a linear accelerator machine. An adequate match was obtained with the spatial resolution matching up to a MTF value of 0.2 and then diverging and the total signal registered in the central fiber was matched for field sizes ranging from 3 cm by 3 cm to 20 cm by 20 cm for 5 cm, 15 cm and 25 cm air gaps within 3%. The design was altered from a hexagonal array of round double cladded fibers to a square array of single cladded square fibers. The spatial resolution was improved from 0.242 lp mm-1 to 0.359 lp mm-1 at an MTF value of 0.5 from the original design to a square array of square fibers 0.5 mm wide separated by 0.25 mm of lead foil. With further optimization of the detector design it may be possible to increase spatial resolution for MV x-ray imaging while maintaining an adequate detection efficiency.

A Simulation of a Novel High Quantum Efficiency Scintillating Fiber Detector with Anti-scatter Properties for Megavoltage X-Ray Imaging

To further develop a MV x-ray portal imaging device with high detection efficiency and adequate spatial resolution for image guided radiation therapy, the experimental results for a prototype detector were matched using Monte-Carlo software to then improve upon the design. The simulation and experiment were carried out using a 6 MV beam from a linear accelerator machine. An adequate match was obtained with the spatial resolution matching up to a MTF value of 0.2 and then diverging and the total signal registered in the central fiber was matched for field sizes ranging from 3 cm by 3 cm to 20 cm by 20 cm for 5 cm, 15 cm and 25 cm air gaps within 3%. The design was altered from a hexagonal array of round double cladded fibers to a square array of single cladded square fibers. The spatial resolution was improved from 0.242 lp mm-1 to 0.359 lp mm-1 at an MTF value of 0.5 from the original design to a square array of square fibers 0.5 mm wide separated by 0.25 mm of lead foil. With further optimization of the detector design it may be possible to increase spatial resolution for MV x-ray imaging while maintaining an adequate detection efficiency.