In regards to Pokhrel et al. Clinical validation of ring-mounted halcyon linac for lung SBRT: Comparison to SBRT-dedicated C-arm linac treatments. JACMP 2021 Jan;22(1):261-70.
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ABSTRACT:
SUBMITTER: Sarkar B
PROVIDER: S-EPMC8200508 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundThe use of total body irradiation (TBI) with linac-based volumetric modulated arc therapy (VMAT) has been steadily increasing. Helical tomotherapy has been applied in TBI and total marrow irradiation to reduce the dose to critical organs, especially the lungs. However, the methodology of TBI with Halcyon™ linac remains unclear. This study aimed to evaluate whether VMAT with Halcyon™ linac can be clinically used for TBI.MethodsVMAT planning with Halcyon™ linac was conducted using a whole-body computed tomography data set. The planning target volume (PTV) included the body cropped 3 mm from the source. A dose of 12 Gy in six fractions was prescribed for 50% of the PTV. The organs at risk (OARs) included the lens, lungs, kidneys, and testes.ResultsThe PTV D98%, D95%, D50%, and D2% were 8.9 (74.2%), 10.1 (84.2%), 12.6 (105%), and 14.2 Gy (118%), respectively. The homogeneity index was 0.42. For OARs, the Dmean of the lungs, kidneys, lens, and testes were 9.6, 8.5, 8.9, and 4.4 Gy, respectively. The V12Gy of the lungs and kidneys were 4.5% and 0%, respectively. The Dmax of the testes was 5.8 Gy. Contouring took 1-2 h. Dose calculation and optimization was performed for 3-4 h. Quality assurance (QA) took 2-3 h. The treatment duration was 23 min.ConclusionsA planning study of TBI with Halcyon™ to set up VMAT-TBI, dosimetric evaluation, and pretreatment QA, was established.
| S-EPMC8670260 | biostudies-literature
Project description:The authors wish to make the following correction to this paper [...].
| S-EPMC8071297 | biostudies-literature
Project description:The DAVID is a transparent, multi-wire transmission-style detector that attaches to a linear accelerator (linac) collimator for use as an in vivo detector. Currently, the normal method for using the DAVID is to measure a signal at the time of phantom-based pretreatment verification and use that signal as a baseline to compare with in vivo measurements for subsequent treatment fractions. The device has previously been shown to be both stable and accurate.(1,2) This work presents the development of a predictive algorithm for the expected signal, eradicating the need to spend time on the linac prior to treatment, and thereby making the process more efficient. The DAVID response at each wire is a consequence of both primary radiation, from the leaf pair associated with the wire, and scatter radiation as a result of radiation incident on other parts of the detector scattering in the Perspex plate. The primary radiation was shown to be linearly proportional to both leaf separation and delivered monitor units (MU). The scatter signal dropped off exponentially with regard to distance. Both of these effects were modeled; the resulting algorithm was used to predict the response from ten five-field IMRT head and neck plans. The system predicted all DAVID signals to within 5%, and was able to detect artificially generated changes in linac output. Having shown that the algorithm works, a new working paradigm is suggested, and the errors that can be detected are outlined.
| S-EPMC5875507 | biostudies-literature
Project description:Non-biting midges of the fly family Chironomidae are extremely abundant and diverse in Arctic regions and are essential components of Arctic ecosystems. Modern identification tools based on documented records of Arctic chironomid species are therefore important for ecological research and environmental monitoring in the region. Here, we provide an updated review of the chironomid fauna of the Svalbard archipelago and the island of Jan Mayen, Norway. Our results show that a total of 73 species distributed across 24 genera in four subfamilies are known from these areas. Our review treats 109 taxa, including nomina dubia and misidentifications. It includes morphological identification keys to all known species as well as photographs of most taxa and DNA barcodes of 66 species. Taxonomic remarks are given for selected taxa, including previous misidentifications and erroneous records. Chironomus islandicus, Tvetenia bavarica, Limnophyes schnelli, Metriocnemus brusti and Metriocnemus fuscipes as well as the genera Allocladius, Corynoneura and Bryophaenocladius are reported from Svalbard for the first time, while Procladius (Holotanypus) frigidus, Stictochironomus psilopterus, Chaetocladius incertus, Orthocladius (Orthocladius) mixtus and Smittia longicosta, previously considered as junior synonyms or nomina dubia, are revived as valid species based on examination of type material or literature. Twenty species within eleven genera are introduced with interim names. Metriocnemus similis is regarded as a junior synonym of Metriocnemus ursinus, and Smittia incerta, Smittia flexinervis and Smittia spitzbergensis are regarded as nomina dubia. Valid taxa no longer considered as part of the Svalbard fauna are Parochlus kiefferi, Arctopelopia barbitarsis, Procladius (Holotanypus) crassinervis, Diamesa lindrothi, Diamesa incallida, Diamesa lundstromi, Chironomus hyperboreus, Sergentia coracina, Camptocladius stercorarius, Chaetocladius dissipatus, Chaetocladius dentiforceps, Chaetocladius laminatus, Chaetocladius perennis, Cricotopus (Cricotopus) humeralis, Cricotopus (Cricotopus) polaris, Hydrosmittia ruttneri, Limnophyes edwardsi, Metriocnemus picipes, Metriocnemus tristellus, Orthocladius (Eudactylocladius) gelidus, Orthocladius (Euorthocladius) thienemanni, Orthocladius (Orthocladius) obumbratus, Orthocladius (Orthocladius) rhyacobius, Paralimnophyes, Paraphaenocladius impensus, Psectrocladius (Monopsectrocladius) calcaratus, Psectrocladius (Psectrocladius) psilopterus, Psectrocladius (Psectrocladius) ventricosus, Smittia lasiophthalma, Smittia lasiops and Zalutschia tatrica.
| S-EPMC7143642 | biostudies-literature
Project description: Not available
| S-EPMC9366869 | biostudies-literature
Project description:PurposeThe aim of this study was to perform a dosimetric evaluation between craniospinal irradiation volumetric modulated arc therapy plans designed for an O-Ring and a conventional C-arm Linac.Methods and materialsTwo adult patients were selected for this study. Two plans were designed one for a TrueBeam Edge and one for Halcyon O-ring Linac for each patient. The evaluation of the plans was conducted in terms of dose volume histogram analysis of the target volume and organs at risk (OARs) along with total plan monitor units and beam-on time. Paired sample t test was performed to compare Dmax and Dmean of OARs for each plan's comparison. The delivery of volumetric modulated arc therapy plans was evaluated using Octavius 4D phantom.ResultsAll plans demonstrated dose distributions with sufficient planned target volume conformity and homogeneity. The Homogeneity Index and Conformity Index for all plans were found comparable. The paired sample t test did not demonstrate significant difference in terms of Dmax and Dmean of OARs between plans for both patients. All plans met the threshold of 90%, with Halcyon plans having higher gamma passing rates.ConclusionsCraniospinal irradiation plans generated for Halcyon and Edge are equivalent in terms of plan quality and dose sparing at OARs. The small variations may have originated from the differences in beam profile or mean energy, the degree of the modulation for each plan and characteristics of multi leaf collimators for each treatment unit. Halcyon is able to deliver a distinctly faster treatment, but Edge provides an automatic rotational correction for patient positioning.
| S-EPMC9830104 | biostudies-literature
