Clinical utility of a 1.5 T magnetic resonance imaging-guided linear accelerator during conventionally fractionated and hypofractionated prostate cancer radiotherapy

Abstract

PurposeTo report our initial experience with 1.5 T magnetic resonance imaging (MRI) linear accelerator (LINAC) in prostate cancer radiotherapy in terms of its use in a radiation oncology clinic.MethodsThe medical records of 14 prostate cancer patients treated with MRI-guided radiotherapy were retrospectively evaluated. The fraction time, adapt-to-position (ATP):adapt-to-shape (ATS) usage rate, machine-associated treatment interruption rate, median gamma pass rate, the percentage of planning target volume receiving at least 95% of the prescription dose coverage value of each ATS fraction, the effect of the learning curve on the fraction time and radiation-related acute gastrointestinal and genitourinary toxicities were evaluated.ResultsFourteen patients have completed their treatment receiving a total of 375 fractions. Six patients (42%) were treated with the moderately hypofractionated regimen, five patients (36%) with conventionally fractionated, and three patients (22%) with the ultra-hypofractionated radiotherapy regimens. The ATP : ATS usage ratio was 3:372. The median fraction time was 46 min (range, 24-81 min). For the 3%/3 mm criterion, median gamma pass rate was 99.4% (range, 94.6–100%). Machine-related treatment interruptions were observed in 11 (2.9%) of 375 fractions, but this interruption rate decreased from 4.1% to 0.8%, after an upgrade. Three patients (22%) had gastrointestinal and five patients (36%) had genitourinary toxicity. No ≥grade 3 toxicity was observed.Conclusion1.5 T MRI-LINAC device could be used as a conventional LINAC device, when the conditions of the radiotherapy center are appropriate. MRI-guided prostate radiotherapy is safe and feasible, and high-quality studies with a larger number of patients and long-term results are needed to better evaluate this new technology.

Noninvasive optoacoustic imaging of breast tumor microvasculature in response to radiotherapy

“…Noninvasive imaging methods offer the potential for longitudinal monitoring of dynamic temporal changes occurring in the tumor microenvironment and allow us to map the spatial heterogeneity of tumor microvessels and tumor oxygenation. Conventional imaging methods such as magnetic resonance imaging (MRI) ( Morgan Tiffany et al, 2019 ; Turkkan et al, 2022 ), positron emission tomography (PET) ( Abravan et al, 2017 ; Jiang et al, 2021 ) and computed tomography (CT) ( Wang et al, 2011 ; Crane Christopher and Koay Eugene, 2016 ) have been used to study tumor blood vessels and oxygenation in animal models and patients. However, these technologies are either more expensive or require the use of ionizing radiation or radioactive isotopes.…”