| 1. |
- Iacobaeus, Christian, et al.
(författare)
-
A novel portal imaging device for advanced radiation therapy
- 2001
-
Ingår i: Nuclear Science, IEEE Transactions on. - Nuclear Science, IEEE Transactions on : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 48:4, Part 2, s. 1496-1502
-
Tidskriftsartikel (refereegranskat)
|
|
| 2. |
- Ansari, Shaquib Rahman, et al.
(författare)
-
Pharmaceutical Quality by Design Approach to Develop High-Performance Nanoparticles for Magnetic Hyperthermia
- 2024
-
Ingår i: ACS Nano. - 1936-0851 .- 1936-086X. ; 18:23, s. 15284-15302
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetic hyperthermia holds significant therapeutic potential, yet its clinical adoption faces challenges. One obstacle is the large-scale synthesis of high-quality superparamagnetic iron oxide nanoparticles (SPIONs) required for inducing hyperthermia. Robust and scalable manufacturing would ensure control over the key quality attributes of SPIONs, and facilitate clinical translation and regulatory approval. Therefore, we implemented a risk-based pharmaceutical quality by design (QbD) approach for SPION production using flame spray pyrolysis (FSP), a scalable technique with excellent batch-to-batch consistency. A design of experiments method enabled precise size control during manufacturing. Subsequent modeling linked the SPION size (6–30 nm) and composition to intrinsic loss power (ILP), a measure of hyperthermia performance. FSP successfully fine-tuned the SPION composition with dopants (Zn, Mn, Mg), at various concentrations. Hyperthermia performance showed a strong nonlinear relationship with SPION size and composition. Moreover, the ILP demonstrated a stronger correlation to coercivity and remanence than to the saturation magnetization of SPIONs. The optimal operating space identified the midsized (15–18 nm) Mn0.25Fe2.75O4 as the most promising nanoparticle for hyperthermia. The production of these nanoparticles on a pilot scale showed the feasibility of large-scale manufacturing, and cytotoxicity investigations in multiple cell lines confirmed their biocompatibility. In vitro hyperthermia studies with Caco-2 cells revealed that Mn0.25Fe2.75O4 nanoparticles induced 80% greater cell death than undoped SPIONs. The systematic QbD approach developed here incorporates process robustness, scalability, and predictability, thus, supporting the clinical translation of high-performance SPIONs for magnetic hyperthermia.
|
|
| 3. |
- Courteille, Olivier, et al.
(författare)
-
Learning through a virtual patient vs. recorded lecture : a comparison of knowledge retention in a trauma case
- 2018
-
Ingår i: International Journal of Medical Education. - : IJME. - 2042-6372. ; 9, s. 86-92
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To compare medical students' and residents' knowledge retention of assessment, diagnosis and treatment procedures, as well as a learning experience, of patients with spinal trauma after training with either a Virtual Patient case or a video-recorded traditional lecture. Methods: A total of 170 volunteers (85 medical students and 85 residents in orthopedic surgery) were randomly allocated (stratified for student/resident and gender) to either a video-recorded standard lecture or a Virtual Patient-based training session where they interactively assessed a clinical case portraying a motorcycle accident. The knowledge retention was assessed by a test immediately following the educational intervention and repeated after a minimum of 2 months. Participants' learning experiences were evaluated with exit questionnaires. A repeated-measures analysis of variance was applied on knowledge scores. A total of 81% (n = 138) of the participants completed both tests. Results: There was a small but significant decline in first and second test results for both groups (F-(1,F-135) = 18.154, p = 0.00). However, no significant differences in short-term and long-term knowledge retention were observed between the two teaching methods. The Virtual Patient group reported higher learning experience levels in engagement, stimulation, general perception, and expectations. Conclusions: Participants' levels engagement were reported in favor of the VP format. Similar knowledge retention was achieved through either a Virtual Patient or a recorded lecture.
|
|
| 4. |
- Hemmingsson, Helena, 1957-, et al.
(författare)
-
Eye-Gaze Control Technology as Early Intervention for a Non-Verbal Young Child with High Spinal Cord Injury : A Case Report
- 2018
-
Ingår i: Technologies. - : MDPI AG. - 2227-7080. ; 6:1
-
Tidskriftsartikel (refereegranskat)abstract
- Assistive technology (AT) can be used as early intervention in order to reduce activity limitations in play and communication. This longitudinal case study examines eye-gaze control technology as early intervention for a young child with high spinal cord injury without the ability to make sounds. The young child was followed by repeated measures concerning performance and communication from baseline at 9 months to 26 months, and finalized at 36 months by field observations in the home setting. The results showed eye-gaze performance and frequency of use of eye-gaze control technology increased over time. Goals set at 15 months concerning learning and using the AT; naming objects and interactions with family was successfully completed at 26 months. Communicative functions regarding obtaining objects and social interaction increased from unintentional actions to purposeful choices and interactions. At 36 months, the toddler was partly independent in eye gazing, used all activities provided, and made independent choices. In conclusion, the results show that a 9-month-old child with profound motor disabilities can benefit from eye-gaze control technology in order to gradually perform activities, socially interact with family members, and make choices.
|
|
| 5. |
- Hollmark, M, 1975-, et al.
(författare)
-
Influence of multiple scattering and energy loss straggling on the absorbed dose distributions of therapeutic light ion beams : I. Analytical pencil beam model.
- 2004
-
Ingår i: Phys Med Biol. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 49:14, s. 3247-3265
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The lateral and longitudinal distributions of absorbed dose of broad and narrowlight ion beams in water are investigated. An analytical algorithm based on thegeneralized Fermi–Eyges theory is developed and used to calculate the effectsof multiple scattering and range straggling on the dose distribution of light ionbeams in water. A first-order Gaussian multiple scattering and energy lossstraggling approach is generally sufficiently accurate for describing the lateraland longitudinal spread of the Bragg peak and the associated energy depositiondistribution of therapeutic light ion beams at ranges of clinical interest. Nuclearreactions are not taken into account in this study. The analytical algorithmgiven in the present study allows an accurate description of the radial spreadand the range straggling of light ions traversing matter. A verification of thisapproach by comparing with experimental data, Monte Carlo methods andother analytical techniques will be presented in a forthcoming paper.
|
|
| 6. |
- Lindborg, L, et al.
(författare)
-
Lineal energy and radiation quality in radiation therapy: model calculations and comparison with experiment
- 2013
-
Ingår i: Physics in Medicine and Biology. - : Institute of Physics: Hybrid Open Access. - 0031-9155 .- 1361-6560. ; 58:10, s. 3089-3105
-
Tidskriftsartikel (refereegranskat)abstract
- Microdosimetry is a recommended method for characterizing radiation quality in situations when the biological effectiveness under test is not well known. In such situations, the radiation beams are described by their lineal energy probability distributions. Results from radiobiological investigations in the beams are then used to establish response functions that relate the lineal energy to the relative biological effectiveness (RBE). In this paper we present the influence of the size of the simulated volume on the relation to the clinical RBE values (or weighting factors). A single event probability distribution of the lineal energy is approximated by its dose average lineal energy ((y) over bar (D)) which can be measured or calculated for volumes from a few micrometres down to a few nanometres. The clinical RBE values were approximated as the ratio of the alpha-values derived from the LQ-relation. Model calculations are presented and discussed for the SOBP of a C-12 ion (290 MeV u(-1)) and the reference Co-60 gamma therapy beam. Results were compared with those for a conventional x-ray therapy beam, a 290 MeV proton beam and a neutron therapy beam. It is concluded that for a simulated volume of about 10 nm, the alpha-ratio increases approximately linearly with the (y) over bar (D)-ratio for all the investigated beams. The correlation between y and alpha provides the evidence to characterize a radiation therapy beam by the lineal energy when, for instance, weighting factors are to be estimated.
|
|
| 7. |
- Palmans, H., et al.
(författare)
-
Fluence correction factors for graphite calorimetry in a low-energy clinical proton beam : I. Analytical and Monte Carlo simulations
- 2013
-
Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 58:10, s. 3481-3499
-
Tidskriftsartikel (refereegranskat)abstract
- The conversion of absorbed dose-to-graphite in a graphite phantom to absorbed dose-to-water in a water phantom is performed by water to graphite stopping power ratios. If, however, the charged particle fluence is not equal at equivalent depths in graphite and water, a fluence correction factor, k(fl), is required as well. This is particularly relevant to the derivation of absorbed dose-to-water, the quantity of interest in radiotherapy, from a measurement of absorbed dose-to-graphite obtained with a graphite calorimeter. In this work, fluence correction factors for the conversion from dose-to-graphite in a graphite phantom to dose-to-water in a water phantom for 60 MeV mono-energetic protons were calculated using an analytical model and five different Monte Carlo codes (Geant4, FLUKA, MCNPX, SHIELD-HIT and McPTRAN.MEDIA). In general the fluence correction factors are found to be close to unity and the analytical and Monte Carlo codes give consistent values when considering the differences in secondary particle transport. When considering only protons the fluence correction factors are unity at the surface and increase with depth by 0.5% to 1.5% depending on the code. When the fluence of all charged particles is considered, the fluence correction factor is about 0.5% lower than unity at shallow depths predominantly due to the contributions from alpha particles and increases to values above unity near the Bragg peak. Fluence correction factors directly derived from the fluence distributions differential in energy at equivalent depths in water and graphite can be described by k(fl) = 0.9964 + 0.0024 . z(w-eq) with a relative standard uncertainty of 0.2%. Fluence correction factors derived from a ratio of calculated doses at equivalent depths in water and graphite can be described by k(fl) = 0.9947 + 0.0024 . z(w-eq) with a relative standard uncertainty of 0.3%. These results are of direct relevance to graphite calorimetry in low-energy protons but given that the fluence correction factor is almost solely influenced by non-elastic nuclear interactions the results are also relevant for plastic phantoms that consist of carbon, oxygen and hydrogen atoms as well as for soft tissues.
|
|
| 8. |
- Waligórski, M P R, et al.
(författare)
-
A simple track structure model of ion beam radiotherapy.
- 2006
-
Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 122:1-4, s. 471-4
-
Tidskriftsartikel (refereegranskat)abstract
- A simple radiotherapy ion beam calculation based on the cellular track structure model, using in vitro cell survival parameters fitted from recent experimental data, is presented. The calculation represents a single-fraction ion exposure (roughly corresponding to a 2 Gy fraction of megavolt X rays) and exploits concepts used in clinical radiotherapy, such as entrance, or 'skin' ion dose. The depth distribution of cells surviving their irradiation by a beam of 385 MeV amu(-1) carbon ions is calculated over the range of the stopping ions, as a sequence of track-segments, in the continuous slowing-down approximation. An interpretation of the 'clinical relative biological effectiveness' concept is suggested.
|
|
| 9. |
- Waligórski, Michael P R, et al.
(författare)
-
Cellular parameters and RBE-LET dependences for modelling heavy-ion radiotherapy.
- 2004
-
Ingår i: Radiother Oncol. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 73:Supplement 2, s. S173-175
-
Tidskriftsartikel (refereegranskat)abstract
- Sets of four parameters (m, Eo, ~o and •) of the cellular track structure model of Katz have been fitted to recently published dataconcerning human melanoma (AA) and mammalian (V79) cells exposed to a variety of lighter ions and to mixed ion-Co60 and ionionirradiation. We discuss the predictive capability of this model and propose standards in reporting cellular radiobiology data forapplication in modelling heavy ion beam radiotherapy.
|
|
| 10. |
- Waligórski, M P R, et al.
(författare)
-
Cellular parameters for track structure modeling of radiation hazard in space.
- 2004
-
Ingår i: Adv Space Res. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 34:6, s. 1378-82
-
Tidskriftsartikel (refereegranskat)abstract
- Based on irradiation with 45 MeV/u N and B ions and with Co-60 c rays, cellular parameters of Katz’s track structure modelhave been fitted for the survival of V79-379A Chinese hamster lung fibroblasts. Cellular parameters representing neoplastictransformations in C3H10T/1/2 cells after their irradiation with heavy ion beams, taken from earlier work, were also used to modelthe radiation hazard in deep space, following the system for evaluating, summing and reporting occupational exposures proposed in1967 by a subcommittee of NCRP. We have performed model calculations of the number of transformations in surviving cells, aftera given fluence of heavy charged particles of initial energy 500 MeV/u, penetrating thick layers of cells. We take the product of celltransformation and survival probabilities, calculated along the path lengths of charged particles using cellular survival and transformationparameters, to represent a quantity proportional to the ‘‘radiation risk factor’’ discussed in the NCRP document. The‘‘synergistic’’ effect of simultaneous charged particle transfers is accounted for by the ‘‘track overlap’’ mode inherent in the model ofKatz.
|
|
