Stereotactic body radiotherapy with a focal boost to the intraprostatic tumor for intermediate and high risk prostate cancer: 5-year efficacy and toxicity in the hypo-FLAME trial.

Background: The addition of an integrated focal boost to the intraprostatic lesion is associated with improved biochemical disease-free survival (bDFS) in patients with intermediate- and high-risk prostate cancer (PCa) in conventionally fractionated radiotherapy. Furthermore, whole gland stereotactic body radiotherapy (SBRT) demonstrated to be non-inferior to conventional radiotherapy for low- and intermediate-risk PCa. To investigate the combination of ultra-hypofractionated prostate SBRT with iso-toxic focal boosting for intermediate- and high-risk PCa, we performed the hypo-FLAME trial.

Post-irradiation darkening model for EBT-3 films characterized using a single lot calibration approach.

In this study, we present a model to correct the progressive post-irradiation darkening of EBT3 films. The model allows for a clinical use of EBT3 using application and calibration films scanned with different post-irradiation times.The model is a post-irradiation time- and dose-dependent power-law function, projecting the scanned transmittance of application films to the transmittance matching the same post-irradiation time of calibration films.

"Scan-(pre)Plan-Treat" Workflow for Bone Metastases Using the Ethos Therapy System: A Single-Center, In Silico Experience.

Purpose: To report on the accuracy of automated delineation, treatment plan quality, and duration of an in-silico "scan-(pre)plan-treat" (SPT) workflow for vertebral bone metastases using a 1 × 8 Gy regimen.

Method And Materials: The cloud-based emulator system of the Ethos therapy system was used to adapt an organ-at-risk-sparing preplan created on the diagnostic CT to the anatomy-of-the-day using the cone beam CT made before treatment.

Results: SPT using the Ethos emulator system resulted in relatively good coverage of the PTV and acceptable dose to the OAR.

From once-weekly to semi-weekly whole prostate gland stereotactic radiotherapy with focal boosting: Primary endpoint analysis of the multicenter phase II hypo-FLAME 2.0 trial.

Background And Purpose: The hypo-FLAME trial showed that once-weekly (QW) focal boosted prostate stereotactic body radiotherapy (SBRT) is associated with acceptable acute genitourinary (GU) and gastrointestinal (GI) toxicity. Currently, we investigated the safety of reducing the overall treatment time (OTT) of focal boosted prostate SBRT from 29 to 15 days.

Material And Methods: Patients with intermediate- and high-risk prostate cancer were treated with SBRT delivering 35 Gy in 5 fractions to the whole prostate gland with an iso-toxic boost up to 50 Gy to the intraprostatic lesion(s) in a semi-weekly (BIW) schedule.

Calibration and time fading characterization of a new optically stimulated luminescence film dosimeter.

Background: Optically stimulated luminescence (OSL) dosimeters produce a signal linear to the dose, which fades with time due to the spontaneous recombination of energetically unstable electron/hole traps. When used for radiotherapy (RT) applications, fading affects the signal-to-dose conversion and causes an error in the final dose measurement. Moreover, the signal fading depends to some extent on treatment-specific irradiation conditions such as irradiation times.

Experimental investigation of dynamic real-time rotation-including dose reconstruction during prostate tracking radiotherapy.

Background: Hypofractionation in prostate radiotherapy is of increasing interest. Steep dose gradients and a large weight on each individual fraction emphasize the need for motion management. Real-time motion management techniques such as multileaf collimator (MLC) tracking or couch tracking typically adjust for translational motion while rotations remain uncompensated with unknown dosimetric impact.

Automated treatment planning of prostate stereotactic body radiotherapy with focal boosting on a fast-rotating O-ring linac: Plan quality comparison with C-arm linacs.

Purpose: The integration of auto-segmentation and automated treatment planning methods on a fast-rotating O-ring linac may improve the time efficiency of online adaptive radiotherapy workflows. This study investigates whether automated treatment planning of prostate SBRT with focal boosting on the O-ring linac could generate plans that are of similar quality as those obtained through manual planning on clinical C-arm linacs.

Methods: For 20 men with prostate cancer, reference treatment plans were generated on a TrueBeam STx C-arm linac with HD120 MLC and a TrueBeam C-arm linac with Millennium 120 MLC using 6 MV flattened dual arc VMAT.

Ga-PSMA-11 PET, F-PSMA-1007 PET, and MRI for Gross Tumor Volume Delineation in Primary Prostate Cancer: Intermodality and Intertracer Variability.

Purpose: To assess the intermodality and intertracer variability of gallium-68 (Ga)- or fluorine-18 (F)-labeled prostate-specific membrane antigen (PSMA) positron emission tomography (PET) and biparametric magnetic resonance imaging (bpMRI)-based gross tumor volume (GTV) delineation for focal boosting in primary prostate cancer.

Methods: Nineteen prospectively enrolled patients with prostate cancer underwent a PSMA PET/MRI scan, divided into a 1:1 ratio between Ga-PSMA-11 and F-PSMA-1007, before radical prostatectomy (IWT140193). Four delineation teams performed manual contouring of the GTV based on bpMRI and PSMA PET imaging, separately.

Six degrees of freedom dynamic motion-including dose reconstruction in a commercial treatment planning system.

Purpose: Intrafractional motion during radiotherapy delivery can deteriorate the delivered dose. Dynamic rotational motion of up to 38 degrees has been reported during prostate cancer radiotherapy, but methods to determine the dosimetric consequences of such rotations are lacking. Here, we create and experimentally validate a dose reconstruction method that accounts for dynamic rotations and translations in a commercial treatment planning system (TPS).

Dosimetric impact of intrafraction prostate rotation and accuracy of gating, multi-leaf collimator tracking and couch tracking to manage rotation: An end-to-end validation using volumetric film measurements.

Background And Purpose: Both gating and tracking can mitigate the deteriorating dosimetric impact of intrafraction translation during prostate stereotactic body radiotherapy (SBRT). However, their ability to manage intrafraction rotation has not yet been thoroughly investigated. The dosimetric accuracy of gating, MLC tracking and couch tracking to manage intrafraction prostate rotation was investigated.

The use of tumour markers in oesophageal cancer to quantify setup errors and baseline shifts during treatment.

Purpose: To prospectively evaluate the feasibility of solid gold marker placement in oesophageal cancer patients and to quantify inter-fractional and intra-fractional (baseline shift) marker motion during radiation treatment. Radiotherapy target margins and matching strategies were investigated.

Materials/methods: Thirty-four markers were implanted by echo-endoscopy in 10 patients.

Optimal Ga-PSMA and F-PSMA PET window levelling for gross tumour volume delineation in primary prostate cancer.

Purpose: This study proposes optimal tracer-specific threshold-based window levels for PSMA PET-based intraprostatic gross tumour volume (GTV) contouring to reduce interobserver delineation variability.

Methods: Nine Ga-PSMA-11 and nine F-PSMA-1007 PET scans including GTV delineations of four expert teams (GTV) and a majority-voted GTV (GTV) were assessed with respect to a registered histopathological GTV (GTV) as the gold standard reference. The standard uptake values (SUVs) per voxel were converted to a percentage (SUV%) relative to the SUV.

Knowledge-Based Assessment of Focal Dose Escalation Treatment Plans in Prostate Cancer.

Purpose: In a randomized focal dose escalation radiation therapy trial for prostate cancer (FLAME), up to 95 Gy was prescribed to the tumor in the dose-escalated arm, with 77 Gy to the entire prostate in both arms. As dose constraints to organs at risk had priority over dose escalation and suboptimal planning could occur, we investigated how well the dose to the tumor was boosted. We developed an anatomy-based prediction model to identify plans with suboptimal tumor dose and performed replanning to validate our model.

Primary endpoint analysis of the multicentre phase II hypo-FLAME trial for intermediate and high risk prostate cancer.

Background And Purpose: Local recurrences after radiotherapy for prostate cancer (PCa) often originate at the location of the macroscopic tumour(s). Since PCa cells are known to be sensitive to high fraction doses, hypofractionated whole gland stereotactic body radiotherapy (SBRT) in conjunction with a simultaneous ablative microboost to the macroscopic tumour(s) within the prostate could be a way to reduce the risk of local failure. We investigated the safety of this treatment strategy.

Stereotactic body radiation therapy with optional focal lesion ablative microboost in prostate cancer: Topical review and multicenter consensus.

Stereotactic body radiotherapy (SBRT) for prostate cancer (PCa) is gaining interest by the recent publication of the first phase III trials on prostate SBRT and the promising results of many other phase II trials. Before long term results became available, the major concern for implementing SBRT in PCa in daily clinical practice was the potential risk of late genitourinary (GU) and gastrointestinal (GI) toxicity. A number of recently published trials, including late outcome and toxicity data, contributed to the growing evidence for implementation of SBRT for PCa in daily clinical practice.

Extended field radiotherapy measurements in a single shot using a BaFBr-based OSL-film.

This work evaluated the use of a class solution specific calibration for an extra-large BaFBr-based optically stimulated luminescence film (OSL; 43  ×  35 cm; Z   =  4.55). The clinical need for such large dosimeters follows from the increased use of extended-field radiation therapy (EFRT).

Validation and IMRT/VMAT delivery quality of a preconfigured fast-rotating O-ring linac system.

Purpose: A fast-rotating O-ring dedicated intensity modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) delivery system, the Halcyon, is delivered by default with a fully preconfigured photon beam model in the treatment planning system (TPS). This work reports on the validation and achieved IMRT/VMAT delivery quality on the system.

Methods: Acceptance testing followed the vendor's installation product acceptance and was supplemented with mechanical QA.

Production of patient-specific electron beam aperture cut-outs using a low-cost, multi-purpose 3D printer.

Electron beam collimators for non-standard field sizes and shapes are typically fabricated using Styrofoam molds to cast the aperture cut-out. These molds are often produced using a dedicated foam cutter, which may be expensive and only serves a single purpose. An increasing number of radiotherapy departments, however, has a 3D printer on-site, to create a wide range of custom-made treatment auxiliaries, such as bolus and dosimetry phantoms.

Volumetric modulated arc therapy of head-and-neck cancer on a fast-rotating O-ring linac: Plan quality and delivery time comparison with a C-arm linac.

Background And Purpose: Linac improvements in gantry speed, leaf speed and dose rate may increase the time-efficiency of volumetric modulated arc therapy (VMAT) delivery. The plan quality achievable with faster VMAT however remains to be investigated. In this study, a fast-rotating O-ring linac with fast-moving leaves is compared with a C-arm linac in terms of plan quality and delivery time for VMAT of head-and-neck cancer (HNC).

Characterization of a novel liquid fiducial marker for multimodal image guidance in stereotactic body radiotherapy of prostate cancer.

Purpose: Liquid fiducial markers have shown to be a promising alternative to solid gold markers in terms of imaging artifact reduction, patient comfort, and compatibility with different imaging modalities. This study aims to investigate the performance of the novel BioXmark liquid marker for state-of-the-art multimodal imaging used in prostate cancer (PCa) radiotherapy, encompassing kV CT/CBCT, multiparametric MRI, and kV x-ray imaging. In addition, automatic detection of the liquid markers in x-ray imaging for prostate motion monitoring during treatment was investigated.

Effects of ovum pick-up frequency and FSH stimulation: a retrospective study on seven years of beef cattle in vitro embryo production.

The aim of this retrospective study was to compare the number of follicles, cumulus oocyte complexes (COCs) and cultured In Vitro Produced (IVP) embryos obtained from 1396 non-stimulated Ovum Pick-up (OPU) sessions on 81 donor animals in a twice weekly OPU scheme. Results were obtained from 640 sessions following FSH-LH superstimulation, on 112 donors subjected to OPU once every 2 weeks. The stimulation protocol started with the insertion of an ear implant containing 3 mg norgestomet (Crestar, Intervet, Belgium) 8 days before puncture (day -8).

Characterisation of low, medium and high responders following FSH stimulation prior to ultrasound-guided transvaginal oocyte retrieval in cows.

In human IVF, the concept of 'low responders' is well known and generally defined as women with poor-response to gonadotrophin stimulation in a previous induction cycle. The objective of this retrospective study is to describe and characterise the concepts of 'low-, medium-, and high-response' and 'low, medium, and high responders' in bovine-assisted reproduction by analysing the OPU-IVF results obtained following 665 gonadotrophin-stimulated sessions conducted in 112 animals, nearly all of which were previously unsuccessful in traditional multiple ovulation and embryo transfer (MOET) programs. They were submitted to OPU and IVP between 1999 and 2003.

Ovum pick up and in vitro embryo production in cows superstimulated with an individually adapted superstimulation protocol.

The aim of this experiment was to apply an ovarian superstimulation protocol prior to ovum pick up (OPU), tailored to the individual donor response, to evaluate its advantages and disadvantages in terms of follicle numbers and diameters, the numbers of retrieved oocytes and day 7 cultured blastocysts. Ten adult non-lactating dairy cows were superstimulated with pFSH and subjected to ovum pick up-in vitro fertilisation (OPU-IVF) 6 times at 2-week intervals. On day 0 of each 2-week period, all follicles >8mm were ablated and an ear implant (Crestar, Intervet, Belgium) was inserted.

Addition of beta-mercaptoethanol or Trolox at the morula/blastocyst stage improves the quality of bovine blastocysts and prevents induction of apoptosis and degeneration by prooxidant agents.

This study was conducted to evaluate the effect of beta-mercaptoethanol (a stimulator of glutathione synthesis) and Trolox (an hydrosoluble analogue of Vitamin E) on bovine embryos cultured from the morula stage (Day 5 post-insemination; pi) under oxidative stress conditions. Culture of embryos with increased doses of Trolox showed a dose-dependent embryotoxicity on Day 8 pi. The use of 400 microM Trolox as well as beta-mercaptoethanol at 100 microM prevented at least partly (P < 0.

Increase of plasma eCG binding rate after administration of repeated high dose of eCG to cows.

Equine chorionic gonadotrophin (eCG) is still used to promote follicular growth in cattle and, more recently with an increased frequency of administration, in ovum pick-up protocols. The aim of this experiment was to verify the possible effect of high frequency of administration on the immune response to eCG. The profiles of eCG binding rate, in the blood of two groups (A, B) of 4 primiparous cross breed beef cows (3-3.