Notes

Conspiratorial Pondering Throughout COVID-19: The Functions associated with Paranoia, Delusion-Proneness, as well as Intolerance involving Anxiety.
Dose measurements within ± 3% were observed between RPLDs that were embedded in MB and B inserts. For the spinal cord and the out-of-target regions surrounded by metal hardware, the dose measured using RPLDs was within 3% different near the titanium screws compared to the dose measured near only the metal rods.

We have successfully performed the first multi-institutional end-to-end dose analysis using an in-house phantom built specifically for post-operative spine SBRT. Selleck 7-Ketocholesterol The differences observed between the measured and planned doses in the presence of metal hardware were clinically insignificant.
We have successfully performed the first multi-institutional end-to-end dose analysis using an in-house phantom built specifically for post-operative spine SBRT. The differences observed between the measured and planned doses in the presence of metal hardware were clinically insignificant.
Auto-contouring performance has been widely studied in development and commissioning studies in radiotherapy, and its impact on clinical workflow assessed in that context. This study aimed to evaluate the manual adjustment of auto-contouring in routine clinical practice and to identify improvements regarding the auto-contouring model and clinical user interaction, to improve the efficiency of auto-contouring.

A total of 103 clinical head and neck cancer cases, contoured using a commercial deep-learning contouring system and subsequently checked and edited for clinical use were retrospectively taken from clinical data over a twelve-month period (April 2019-April 2020). The amount of adjustment performed was calculated, and all cases were registered to a common reference frame for assessment purposes. The median, 10th and 90th percentile of adjustment were calculated and displayed using 3D renderings of structures to visually assess systematic and random adjustment. Results were also compared to inter-observer variation reported previously. Assessment was performed for both the whole structures and for regional sub-structures, and according to the radiation therapy technologist (RTT) who edited the contour.

The median amount of adjustment was low for all structures (<2mm), although large local adjustment was observed for some structures. The median was systematically greater or equal to zero, indicating that the auto-contouring tends to under-segment the desired contour.

Auto-contouring performance assessment in routine clinical practice has identified systematic improvements required technically, but also highlighted the need for continued RTT training to ensure adherence to guidelines.
Auto-contouring performance assessment in routine clinical practice has identified systematic improvements required technically, but also highlighted the need for continued RTT training to ensure adherence to guidelines.While proton therapy offers an excellent dose conformity and sparing of organs at risk, this can be compromised by uncertainties, e.g. organ motion. This study aimed to investigate the influence of cardiac motion on the contoured oesophagus using electrocardiogram-triggered imaging and to assess the impact of this motion on the robustness of proton therapy plans in oesophageal cancer patients. Limited cardiac-induced motion of the oesophagus was observed with a negligible impact on the robustness of proton therapy plans. Therefore, our data suggest that cardiac motion may be safely ignored in the robust optimisation strategy for proton planning in oesophageal cancer.
Postmastectomy breast reconstruction involves the insertion of a temporary tissue expander, which contains a metal injection port. The purpose of this study was to determine the magnitude and dosimetric impact of the inter-fractional positional variations of the port for patients treated with radiation.

For nine breast cases treated on Tomotherapy, the deviation of the port in the daily MVCT from its reference position was measured in the three cardinal directions. The dosimetric effects of the measured errors were evaluated for two classes of error Internal Port Error (IPE) and Patient Registration Error (PRE). For each class, dose accumulation was done for daily measured errors and a systematic error.

Inter-fractional positional errors of the port were small, with 87% of the deviations below 5mm, but errors larger than 1.5cm were observed. The cumulative effect of the daily measured and systematic IPE decreased target coverage by as much as 2.8% and 3.5%, respectively. The cumulative effect of the daily measured PRE decreased target coverage by an average of 3.5%. The cumulative effect of a systematic PRE significantly decreased target coverage by an average of 16%.

The presence of IPE over the course of treatment had minimal clinical impact while PRE had a greater impact on clinically-relevant regions. The robustness of treatment delivery can be improved by assigning the port its appropriate density during planning despite contouring uncertainties due to metal artefacts, and by prioritizing anatomical alignment over port alignment during daily registration.
The presence of IPE over the course of treatment had minimal clinical impact while PRE had a greater impact on clinically-relevant regions. The robustness of treatment delivery can be improved by assigning the port its appropriate density during planning despite contouring uncertainties due to metal artefacts, and by prioritizing anatomical alignment over port alignment during daily registration.Proton beam therapy (PBT) for uveal melanoma (UM) is performed in sitting position, while the acquisition of the Magnetic resonance (MR)-images for treatment planning is performed in supine position. We assessed the effect of this difference in position on the eye- and tumour- shape. Seven subjects and six UM-patients were scanned in supine and a seating mimicking position. The distances between the tumour/sclera in both positions were calculated. The median distance between both positions was 0.1 mm. Change in gravity direction produced no substantial changes in sclera and tumour shape, indicating that supinely acquired MR-images can be used to plan ocular-PBT.
There is a continual need for more accurate and effective dosimetric systems for quality assurance (QA) as radiotherapy evolves in complexity. The purpose of this project was to introduce a new system that minimally perturbs the main beam, while assessing its real time 2D dose-rate and field shapes. The system combined reusability, linear dose-rate response, and high spatial and time resolution in a single radiation detection technology that can be applied to surface dose estimation and QA.

We developed a 2D prototype system consisting of a camera, focusing lenses and short pass filter, placed on the head of a linear accelerator, facing an Al
O
C,Mg radioluminescent film. To check the appropriateness of multi-leaf collimator, stability/reproducibility QA tests were prepared using the treatment planning system including the routinely used alternating leaves, chair and pyramid checks.

The Al
O
C,Mg film did not perturb the dose vs
depth dose curves determined with a point detector (-0.5% difference). Our results showed a dose-rate linear film response (R
=0.999), from 5 to 600MU/min. Measured output factors agreed with reference data within ~1%, indicating a potential for small field dosimetry. Both chair and pyramid measured profiles were comparable with those obtained with the treatment planning system within 1%. The alternating leaves test showed an average discrepancy in the valleys of 14%.

The prototype demonstrated promising results. It obviated the need for corrections regarding the relative position of the camera, confirming accurate dose-rate delivery and detection of radiation fields.
The prototype demonstrated promising results. It obviated the need for corrections regarding the relative position of the camera, confirming accurate dose-rate delivery and detection of radiation fields.
Spinal stereotactic body radiotherapy (SBRT) involves large dose gradients and high geometrical accuracy is therefore required. The aim of this work was to assess residual intra-fraction error with a tracking robotic system for non-immobilized patients. Shifts from the first alignment (i.e. mimicking the unavailability of tracking) were also quantified.

Forty-two patients treated for spinal metastasis (128 fractions, 4220 images) were analyzed. Residual error was quantified as the difference between translations/rotations referring to consecutive x-ray images during delivery (tracking) and to the initial set-up (no-tracking). The error distribution for each fraction/patient and the entire population was assessed for each axis/rotation angle. The impact of lesion sites, fractionation and patient's pain (VAS score) were investigated. Finally, the dosimetric impact of residual motion was quantified in the four most affected fractions.

Mean overall errors (OE) were near 0 (SD<0.1mm). Residual translations/rotations >1mm/1° were found in less than 1.5%/1% of measurements. Lesion site and fractionation showed no impact. The dosimetric impact in the most affected fractions was negligible. For "no-tracking", mean OE was <1mm/0.5°; less than 2% of displacements were >2mm/1° within 10min from the start of treatment with an increasing probability of shifts >2mm over time. A significantly higher fraction of OE≥2mm was found for patients with pain in case of no-tracking.

Spine tracking with a latest-generation robotic system is highly efficient for non-immobilized patients residual error is time independent and close to 0. For delivery times >7-8min, tracking should be considered as mandatory for non-immobilized patients.
7-8 min, tracking should be considered as mandatory for non-immobilized patients.
Total body irradiation (TBI) is a treatment used in the conditioning of patients prior to hematopoietic stem cell transplantation. We developed an extended-distance TBI technique using a conventional linac with multi-leaf collimator to deliver a homogeneous dose, and spare critical organs.

Patients were treated either in lateral recumbent or in supine position depending on the dose level. A conventional linac was used with the patient midline at 350cm from the beam source. A series of beams was prepared manually using a 3D treatment planning system (TPS) aiming to improve dose homogeneity, spare the organs at risk and facilitate accurate patient positioning. An optimized dose calculation model for extended-distance treatments was developed using phantom measurements. During treatment, in-vivo dosimetry was performed using electronic dosimeters, and accurate positioning was verified using a mobile megavoltage imager. We analyzed dose volume histogram parameters for 19 patients, and in-vivo measurements for 46 delivered treatment fractions.

Optimization of the dose calculation model for TBI improved dose calculation by 2.1% at the beam axis, and 17% at the field edge. Treatment planning dose objectives and constraints were met for 16 of 19 patients. Results of in-vivo dosimetry were within the set limitations (±10%) with mean deviations of 3.7% posterior of the lungs and 0.6% for the abdomen.

We developed a TBI treatment technique using a conventional linac and TPS that can reliably be used in the conditioning regimen of patients prior to stem cell transplantation.
We developed a TBI treatment technique using a conventional linac and TPS that can reliably be used in the conditioning regimen of patients prior to stem cell transplantation.
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