Integrating cine EPID, dynamic delivery, and the off-axis Winston-Lutz test to enhance quality control in multiple brain metastasis stereotactic radiotherapy.

PURPOSE: Stereotactic radiotherapy (SRT) has transformed cancer treatment, especially for brain metastases. Ensuring accurate SRT delivery is crucial, with the Winston-Lutz test being an important quality control tool. Off-axis Winston-Lutz (OAWL) tests are designed for accuracy assessment, but most are limited to fixed angles and hampered by local-field shifts caused by suboptimal Multi-Leaf Collimator (MLC) positioning. This study introduces a new OAWL approach for quality control in multi-brain-metastasis SRT. Utilizing cine Electronic Portal Imaging Device (EPID) images, it can be used with dynamic conformal arc (DCA) therapy. However, dynamic OAWL (DOAWL) is prone to more local-field shifts due to dynamic MLC movements. A two-step DOAWL is proposed: step 1 calculates local-field shifts using dynamic MLC movements in the beam-eye view data from the Treatment Planning System (TPS), while step 2 processes cine EPID images with an OAWL algorithm to isolate true deviations. METHODS: Validation involved an anthropomorphic head phantom with metallic ball-bearings, Varian TrueBeam STx accelerator delivering six coplanar/non-coplanar DCA beams, cine EPID, and ImageJ's OAWL analysis algorithm. RESULTS: Inherent local-field shifts ranged from 0.11 to 0.49 mm; corrected mean/max EPID-measured displacement was 0.34/1.03 mm. Few points exceeded 0.75/1.0-mm thresholds. CONCLUSIONS: This two-step DOAWL test merges cine-EPID acquisitions, DCA, OAWL, and advanced analysis and offers effective quality control for multi-brain-metastasis SRT. Its routine implementation may also improve physicist knowledge of the treatment precision of their machines.

Evaluation of the ability of the Brainlab Elements Cranial Distortion Correction algorithm to correct clinically relevant MRI distortions for cranial SRT.

PURPOSE: Cranial stereotactic radiotherapy (SRT) requires highly accurate lesion delineation. However, MRI can have significant inherent geometric distortions. We investigated how well the Elements Cranial Distortion Correction algorithm of Brainlab (Munich, Germany) corrects the distortions in MR image-sets of a phantom and patients. METHODS: A non-distorted reference computed tomography image-set of a CIRS Model 603-GS (CIRS, Norfolk, VA, USA) phantom was acquired. Three-dimensional T1-weighted images were acquired with five MRI scanners and reconstructed with vendor-derived distortion correction. Some were reconstructed without correction to generate heavily distorted image-sets. All MR image-sets were corrected with the Brainlab algorithm relative to the computed tomography acquisition. CIRS Distortion Check software measured the distortion in each image-set. For all uncorrected and corrected image-sets, the control points that exceeded the 0.5-mm clinically relevant distortion threshold and the distortion maximum, mean, and standard deviation were recorded. Empirical cumulative distribution functions (eCDF) were plotted. Intraclass correlation coefficient (ICC) was calculated. The algorithm was evaluated with 10 brain metastases using Dice similarity coefficients (DSC). RESULTS: The algorithm significantly reduced mean and standard deviation distortion in all image-sets. It reduced the maximum distortion in the heavily distorted image-sets from 2.072 to 1.059 mm and the control points with > 0.5-mm distortion fell from 50.2% to 4.0%. Before and especially after correction, the eCDFs of the four repeats were visually similar. ICC was 0.812 (excellent-good agreement). The algorithm increased the DSCs for all patients and image-sets. CONCLUSION: The Brainlab algorithm significantly and reproducibly ameliorated MRI distortion, even with heavily distorted images. Thus, it increases the accuracy of cranial SRT lesion delineation. After further testing, this tool may be suitable for SRT of small lesions.

EYE LENS RADIATION EXPOSURE OF WORKERS DURING MEDICAL INTERVENTIONAL PROCEDURES AND SURGERY.

To evaluates the eye-lens radiation exposure of workers during medical interventional procedures and surgery in a military hospital as well as of the equine veterinarians. The measures represent the exposure in a normal workload schedule of ninety randomly selected workers over a 3-month period, extrapolated to 1 year. The eye-lens dosemeters were placed near the eye closest to the radiation source (Carinou, E., Ferrari, P., Bjelac, O. C., Gingaume, M., Merce, M. S. and O'Connor, U. Eye lens monitoring for interventional radiology personnel: dosemeters, calibration and practical aspects of H p (3) monitoring. A 2015 review. J. Radiol. Prot. 2015;35(3): R17-R34). Three models of eye-lens dosemeters (Dosilab, Landauer and IRSN) were assessed in term of ergonomics. The annual estimation of eye-lens doses did not reach the annual dose limit of 20 mSv revised by the ICRP, ranged from 0.00 to 18.12 mSv with a mean of 0.96 ± 2.28 mSv. However, these results cannot be representative of a heavy workload or incident situations for which radiation exposure to the eye-lens could exceed this limit. The IRSN dosemeter model was considered the most convenient.

DosiKit, a New Portable Immunoassay for Fast External Irradiation Biodosimetry.

DosiKit is a new field-radiation biodosimetry immunoassay for rapid triage of individuals exposed to external total-body irradiation. Here, we report on the validation of this immunoassay in human blood cell extracts 0.5 h after in vitro exposure to 137Cs gamma rays, using γ-H2AX analysis. First, calibration curves were established for five donors at doses ranging from 0 to 10 Gy and dose rates ranging from ∼0.8 to ∼3 Gy/min. The calibration curves, together with a γ-H2AX peptide scale, enabled the definition of inter-experimental correction factors. Using previously calculated correction factors, blind dose estimations were performed at 0.5 h postirradiation, and DosiKit performance was compared against concomitant dicentric chromosome assay (DCA), the current gold standard for external irradiation biodosimetry. A prototype was then assembled and field tested. We show that, despite significant inter-individual variations, DosiKit can estimate total-body irradiation doses from 0.5 to 10 Gy with a strong linear dose-dependent signal and can be used to classify potentially exposed individuals into three dose ranges: below 2 Gy, between 2 and 5 Gy and above 5 Gy. The entire protocol can be performed in 45 min, from sampling to dose estimation, with a new patient triaged every 10 min. While DCA enables precise measurement of doses below 5 Gy, it is a long and difficult method. In contrast, DosiKit is a quick test that can be performed directly in the field by operational staff with minimal training, and is relevant for early field triage and identification of individuals most likely to experience acute radiation syndrome. These findings suggest that DosiKit and DCA are complementary and should be combined for triage in a mass scale event. While the proof-of-concept reported here validates the use of DosiKit at 0.5 h postirradiation, further studies are needed to calibrate and evaluate the performance of the DosiKit assay at longer times after irradiation.

Medical management of a cutaneous contamination.

The authors propose a process to improve the medical management of a cutaneous contamination in two ways: firstly by analysis of practices and products of decontamination used; secondly, by developing computer tools for the occupational physicians. This software will allow them to have a rapid dosimetric assessment in the event of a skin contamination by radioactive particles and will help them in their diagnostic and therapeutic decisions. A standardized data sheet was created allowing the exhaustive collection of adequate information in order to evaluate the skin dose. The selection of appropriate monitoring equipment with a 1 cm2 detector, depending on the place and on the surface of the contaminated area, will allow the evaluation and the quantification of the surface activities. A tool has been made as a software package, named Cutadose®, allowing the assessment of the skin dose in situ as well as the efficacy of the prescribed therapy.

Prolonged survival for patients with newly diagnosed, inoperable glioblastoma with 3-times daily ultrafractionated radiation therapy.

Ultrafractionation of radiation therapy is a novel regimen consisting of irradiating tumors several times daily, delivering low doses (<0.75 Gy) at which hyperradiosensitivity occurs. We recently demonstrated the high efficiency of ultrafractionated radiotherapy (RT) on glioma xenografts and report here on a phase II clinical trial to determine the safety, tolerability, and efficacy of an ultrafractionation regimen in patients with newly and inoperable glioblastoma (GBM). Thirty-one patients with histologically proven, newly diagnosed, and unresectable supratentorial GBM (WHO grade IV) were enrolled. Three daily doses of 0.75 Gy were delivered at least 4 hours apart, 5 days per week over 6-7 consecutive weeks (90 fractions for a total of 67.5 Gy). Conformal irradiation included the tumor bulk with a margin of 2.5 cm. The primary end points were safety, toxicity, and tolerability, and the secondary end points were overall survival (OS) and progression-free survival (PFS). Multivariate analysis was used to compare the OS and PFS with the EORTC-NCIC trial 26981-22981/CE.3 of RT alone vs radiation therapy and temozolomide (TMZ). The ultrafractionation radiation regimen was safe and well tolerated. No acute Grade III and/or IV CNS toxicity was observed. Median PFS and OS from initial diagnosis were 5.1 and 9.5 months, respectively. When comparing with the EORTC/NCIC trial, in both PFS and OS multivariate analysis, ultrafractionation showed superiority over RT alone, but not over RT and TMZ. The ultrafractionation regimen is safe and may prolong the survival of patients with GBM. Further investigation is warranted and a trial associating ultra-fractionation and TMZ is ongoing.

Comparison of fractional flow reserve of composite Y-grafts with saphenous vein or right internal thoracic arteries.

BACKGROUND: Composite Y-grafts, using the left internal thoracic artery as the inflow, allow a more efficient use of conduits without the need to touch a diseased ascending aorta. Among other conduits, the saphenous vein graft may be an alternative to the radial artery in elderly patients. PATIENTS AND METHODS: We evaluated the hemodynamic characteristics of 17 composite Y-grafts made with the left internal thoracic artery anastomosed to the left anterior descending coronary artery in all cases and with either the free right internal thoracic artery (RITA group, n = 10) or a saphenous vein graft (SVG group, n = 7) implanted proximally to the left internal thoracic artery and distally to the circumflex territory 6 months after the operation. RESULTS: At baseline, the pressure gradient measured with a 0.014-inch pressure wire was minimal between the aorta and the internal thoracic artery stem (2 +/- 1 mm Hg), the internal thoracic artery and left anterior descending (4 +/- 2 mm Hg), the internal thoracic artery and left circumflex (3 +/- 1 mm Hg), and the saphenous vein graft and left circumflex (2 +/- 2 mm Hg). During hyperemia induced by adenosine, the pressure gradient increased significantly to 6 +/- 2 mm Hg in the internal thoracic artery stem, 9 +/- 4 mm Hg in the internal thoracic artery and left anterior descending artery, 9 +/- 3 mm Hg in the internal thoracic artery and left circumflex, and 7 +/- 4 mm Hg in the saphenous vein graft and left circumflex. Fractional flow reserve was 0.94 +/- 0.02 in internal thoracic artery stem, 0.90 +/- 0.04 mm Hg in the internal thoracic artery and left anterior descending, 0.91 +/- 0.03 mm Hg in the internal thoracic artery and left circumflex, and 0.92 +/- 0.06 mm Hg in the saphenous vein graft and left circumflex. No difference between the two types of composite Y-grafts was observed for pressure gradients or fractional flow reserve measured in internal thoracic artery stem or in distal branches. CONCLUSIONS: Composite Y-grafts with saphenous vein or right internal thoracic arteries allow similar and adequate reperfusion of the left system with minimal resistance to maximal flow and an even distribution of flow in both distal branches.