Intra- inter-observer repeatability in liver computed tomography volumetry in patients undergoing radioembolization simulation.

PURPOSE: The careful evaluation of MDCT is an essential step for the treatment planning in pre-treatment imaging work-up for Trans-Arterial Radio Embolization (TARE). It may provide unique volumetric data (CTVs), which are information useful for an effective and safe TARE. The purpose of this study is to demonstrate that the radiographer is able to calculate CTVs of TARE simulation with the same precision as the interventional radiologist. METHODS: This study retrospectively considers 17 consecutive patients (8 males, 9 females; mean age 66.3 ± 13.2 years) who underwent pre-treatment work-up for TARE, between May 2019 and February 2020 (trial ID:2234 - protocol). For each patient, four specific parameters are evaluated from MDCT achieved during treatment simulation: healthy liver volume (HLV), the whole hepatic parenchyma (THV = healthy liver and TTV = tumour) involved by TARE, and whole liver volume (WLV). Four independent observers-R1 (expert interventional radiologist), T1, T2, and T3 (radiographers, with different experiences in the field of interventional radiology)-are involved in the imaging analysed. RESULTS: All the 4 observers detected the same number of hepatic lesion(s) per patient. Regarding the three radiographers, the intra-observer reliability for CTVs is very high 0.997 to 1.000 (95%CI). Also inter-observer reproducibility between radiographers is excellent regarding CTVs, 0.965 to 0.999 (95%CI). The accuracy of radiographer evaluation is very high 0.964 to 0.999 (95%CI). CONCLUSIONS AND IMPLICATIONS FOR PRACTICE: The high intra- and inter-observer reproducibility shows that a properly trained radiographers might have the same accuracy as interventional radiologists, in assessing liver CTV data for planning TARE.

Effects of Sex and Age on Fat Fraction, Diffusion-Weighted Image Signal Intensity and Apparent Diffusion Coefficient in the Bone Marrow of Asymptomatic Individuals: A Cross-Sectional Whole-Body MRI Study.

We aimed to describe the relationships between the relative fat fraction (%FF), muscle-normalized diffusion-weighted (DW) image signal intensity and water apparent diffusion coefficient (ADC), sex and age for normal bone marrow, in the normal population. Our retrospective cohort consisted of 100 asymptomatic individuals, equally divided by sex and 10-year age groups, who underwent whole-body MRI at 1.5 T for early cancer detection. Semi-automated segmentation of global bone marrow volume was performed using the DW images and the resulting segmentation masks were projected onto the ADC and %FF maps for extraction of parameter values. Differences in the parameter values between sexes at age ranges were assessed using the Mann-Whitney and Kruskal-Wallis tests. The Spearman correlation coefficient r was used to assess the relationship of each imaging parameter with age, and of %FF with ADC and normalized DW signal intensity values. The average %FF of normal bone marrow was 65.6 ± 7.2%, while nSIb50, nSIb900 and ADC were 1.7 ± 0.5, 3.2 ± 0.9 and 422 ± 67 µm2/s, respectively. The bone marrow %FF values increased with age in both sexes (r = 0.63 and r = 0.64, respectively, p < 0.001). Values of nSIb50 and nSIb900 were higher in younger women compared to men of the same age groups (p < 0.017), but this difference decreased with age. In our cohort of asymptomatic individuals, the values of bone marrow relative %FF, normalized DW image signal intensity and ADC indicate higher cellularity in premenopausal women, with increasing bone marrow fat with aging in both sexes.

First clinical application of a prompt gamma based in vivo proton range verification system.

BACKGROUND AND PURPOSE: To improve precision of particle therapy, in vivo range verification is highly desirable. Methods based on prompt gamma rays emitted during treatment seem promising but have not yet been applied clinically. Here we report on the worldwide first clinical application of prompt gamma imaging (PGI) based range verification. MATERIAL AND METHODS: A prototype of a knife-edge shaped slit camera was used to measure the prompt gamma ray depth distribution during a proton treatment of a head and neck tumor for seven consecutive fractions. Inter-fractional variations of the prompt gamma profile were evaluated. For three fractions, in-room control CTs were acquired and evaluated for dose relevant changes. RESULTS: The measurement of PGI profiles during proton treatment was successful. Based on the PGI information, inter-fractional global range variations were in the range of ±2 mm for all evaluated fractions. This is in agreement with the control CT evaluation showing negligible range variations of about 1.5mm. CONCLUSIONS: For the first time, range verification based on prompt gamma imaging was applied for a clinical proton treatment. With the translation from basic physics experiments into clinical operation, the potential to improve the precision of particle therapy with this technique has increased considerably.