| 1. |
- Adrian, Gabriel, et al.
(författare)
-
The FLASH effect depends on oxygen concentration
- 2019
-
Ingår i: British Journal of Radiology. - : British Institute of Radiology. - 1748-880X .- 0007-1285. ; 93:1106
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Recent in vivo results have shown prominent tissue sparing effect of radiotherapy with ultra-high dose rates (FLASH) compared to conventional dose rates (CONV). Oxygen depletion has been proposed as the underlying mechanism, but in vitro data to support this have been lacking. The aim of the current study was to compare FLASH to CONV irradiation under different oxygen concentrations in vitro. METHODS: Prostate cancer cells were irradiated at different oxygen concentrations (relative partial pressure ranging between 1.6 and 20%) with a 10 MeV electron beam at a dose rate of either 600 Gy/s (FLASH) or 14 Gy/min (CONV), using a modified clinical linear accelerator. We evaluated the surviving fraction of cells using clonogenic assays after irradiation with doses ranging from 0 to 25 Gy. RESULTS: Under normoxic conditions, no differences between FLASH and CONV irradiation were found. For hypoxic cells (1.6%), the radiation response was similar up to a dose of about 5-10 Gy, above which increased survival was shown for FLASH compared to CONV irradiation. The increased survival was shown to be significant at 18 Gy, and the effect was shown to depend on oxygen concentration. CONCLUSION: The in vitro FLASH effect depends on oxygen concentration. Further studies to characterize and optimize the use of FLASH in order to widen the therapeutic window are indicated. ADVANCES IN KNOWLEDGE: This paper shows in vitro evidence for the role of oxygen concentration underlying the difference between FLASH and CONV irradiation.
|
|
| 2. |
- Fransson, Kristin, et al.
(författare)
-
Miljöhandbokför upphandlare
- 2015
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hållbar utveckling innefattar såväl social, ekonomisk som miljömässig hållbar utveckling.I Miljöhandboken kommer dessa tre aspekter av hållbar utveckling att behandlas,dock ligger störst fokus på miljöaspekterna.Miljöhandboken ska hjälpa upphandlare att ställa relevanta miljökrav vid upphandlingoch är ett komplement till exempelvis Konkurrensverkets (f.d. Miljöstyrningsrådets)upphandlingskriterier och ska bidra med fakta kring hur miljökrav kan ställas.Miljökrav vid upphandling kan innefatta bl. a. energianvändning, livslängd, skadligaämnen, strålning, återvinning och miljöledningssystem. Kravens betydelse påverkasbl. a. av upphandlingens omfattning och miljömognaden inom produktsegmentet. Imiljöhandboken presenteras inga specifika kriterier eller gränsvärden för olika miljöaspekter,i stället ges länkar till exempelvis lagstiftning, myndigheter och miljömärkningar.Detta för att kriterier och gränsvärden uppdateras kontinuerligt som en följdav teknikutveckling men också för att den samlade kunskapen om vad som är miljöproblemständigt växer och kan ge upphov till nya kriterier och gränsvärden. Tyngdpunkteni denna handbok ligger på miljöpåverkan ur ett livscykelperspektiv, vilket innebäratt hänsyn tas till miljöpåverkan från utvinning av råmaterial till resthantering aven produkt.
|
|
| 3. |
- Haraldsson, André, et al.
(författare)
-
A Helical tomotherapy as a robust low-dose treatment alternative for total skin irradiation
- 2019
-
Ingår i: Journal of Applied Clinical Medical Physics. - : Wiley. - 1526-9914. ; 20:5, s. 44-54
-
Tidskriftsartikel (refereegranskat)abstract
- Mycosis fungoides is a disease with manifestation of the skin that has traditionally been treated with electron therapy. In this paper, we present a method of treating the entire skin with megavoltage photons using helical tomotherapy (HT), verified through a phantom study and clinical dosimetric data from our first two treated patients. A whole body phantom was fitted with a wetsuit as bolus, and scanned with computer tomography. We accounted for variations in daily setup using virtual bolus in the treatment plan optimization. Positioning robustness was tested by moving the phantom, and recalculating the dose at different positions. Patient treatments were verified with in vivo film dosimetry and dose reconstruction from daily imaging. Reconstruction of the actual delivered dose to the patients showed similar target dose as the robustness test of the phantom shifted 10 mm in all directions, indicating an appropriate approximation of the anticipated setup variation. In vivo film measurements agreed well with the calculated dose confirming the choice of both virtual and physical bolus parameters. Despite the complexity of the treatment, HT was shown to be a robust and feasible technique for total skin irradiation. We believe that this technique can provide a viable option for Tomotherapy centers without electron beam capability.
|
|
| 4. |
- Haraldsson, André, et al.
(författare)
-
Implementing safe and robust Total Marrow Irradiation using Helical Tomotherapy – A practical guide
- 2019
-
Ingår i: Physica Medica. - : Elsevier BV. - 1120-1797. ; 60, s. 162-167
-
Tidskriftsartikel (refereegranskat)abstract
- Total Marrow Irradiation (TMI) with Helical Tomotherapy is a radiotherapy treatment technique that targets bone marrow and sanctuary sites prior to stem cell or bone marrow transplantation (SCT/BMT). TMI is a complex procedure that involves several critical steps that all need to be carefully addressed for a successful implementation, such as dose homogeneity in field junctions, choice of target margins, integrity of treatment and back-up planning. In this work we present our solution for a robust and reproducible workflow throughout the treatment chain and data for twenty-three patients treated to date. Material & Methods: Patients were immobilized in a whole body vacuum cushion and thermoplastic mask. CT-scanning and treatment were performed in two parts with field matching at the upper thigh. Target consisted of marrow containing bone and sanctuary sites. Lungs, kidneys, bowel, heart and liver were defined as organs at risk (OAR). A fast surface scanning system was used to position parts of the body not covered by the imaging system (MVCT) as well as to reduce treatment time. Results: All patients completed their treatment and could proceed with SCT/BMT. Doses to OARs were significantly reduced and target dose homogeneity was improved compared to TBI. Robustness tests performed on field matching and patient positioning support that the field junction technique is adequate. Replacing MVCT with optical surface scanning reduced the treatment time by 25 min per fraction. Conclusion: The methodology presented here has shown to provide a safe, robust and reproducible treatment for Total Marrow Irradiation using Tomotherapy.
|
|
| 5. |
- Jönsson, Mattias, et al.
(författare)
-
Technical evaluation of a laser-based optical surface scanning system for prospective and retrospective breathing adapted computed tomography.
- 2015
-
Ingår i: Acta Oncologica. - 1651-226X. ; 54:2, s. 261-265
-
Tidskriftsartikel (refereegranskat)abstract
- Background. For breathing adapted radiotherapy, the same motion monitoring system can be used for imaging and triggering of the accelerator. Purpose. To evaluate a new technique for prospective gated computed tomography (CT) and four-dimensional CT (4DCT) using a laser based surface scanning system (Sentinel(™), C-RAD, Uppsala, Sweden). The system was compared to the AZ-733V respiratory gating system (Anzai Medical, Tokyo, Japan) and the Real-Time Position Management System (RPM(™)) (Varian Medical Systems, Palo Alto, CA, USA). Material and methods. Temporal accuracy was evaluated using a moving phantom programmed to move a platform along trajectories following a sin(6)(ωt) function with amplitudes from 6 to 20 mm and periods from 2 to 5 s during 120 s while the motion was recorded. The recorded data was Fourier transformed and the peak area at the fundamental and harmonic frequencies compared to data generated using the same sinusoidal function. For verification of the 4DCT reconstruction process, the phantom was programmed to move along a sinusoidal trajectory. Ten phase series were reconstructed. The distance from the couch to the platform was measured in each image. By fitting the function sin(ωt-ϕ) to the values measured in the images corresponding to each slice, the phase of each image was verified. Results and conclusion. In the recorded data, the peak area at the fundamental frequency covered on average 104 ± 4%, 102 ± 4% and 91 ± 27% of the peak area in the generated data for the Sentinel(™), RPM(™) and AZ-733V systems, respectively. All systems managed to resolve both harmonic frequencies. The second experiment showed that all images were sorted into the correct series using breathing data recorded by each system. The systems generated very similar results, however, it is preferable to use the same system both for imaging and treatment.
|
|
| 6. |
- Kristensson, Elias, et al.
(författare)
-
Quantification of the absorbed dose in 3D by means of advanced optical diagnostics based on structured illumination
- 2015
-
Ingår i: 8th International Conference on 3D Radiation Dosimetry (IC3DDOSE). - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 573, s. 012010-012010
-
Konferensbidrag (refereegranskat)abstract
- The purpose of this study was to present a novel optical diagnostic tool that corrects for undesired contribution of multiply scattered light, thus opening up for e.g. quantitative optical CT measurements of opaque samples. The approach is based on a technique called Structured Illumination (SI), which is commonly employed within microscopic imaging to enhance the depth-resolution. The concept of SI applies for many types of source-detector arrangements and the configuration employed in this paper relies on side-scattering detection. A nPAG polymer gel phantom was irradiated using 6 MV beam. Three-dimensional information was obtained by translating the sample perpendicular to the direction of light, thus sequentially probing different sections. These were then stacked together to form a 3D representation of the sample. By altering the polarization of the laser light during the data acquisition it was discovered that the aggregates responsible for the scattering of light followed Rayleigh scattering, implying that their individual sizes are smaller than, or in the order of, 500 nm.
|
|
| 7. |
- Kügele, Malin, et al.
(författare)
-
Surface guided radiotherapy (SGRT) improves breast cancer patient setup accuracy
- 2019
-
Ingår i: Journal of Applied Clinical Medical Physics. - : Wiley. - 1526-9914. ; , s. 61-68
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The purpose of the study was to investigate if surface guided radiotherapy (SGRT) can decrease setup deviations for tangential and locoregional breast cancer patients compared to conventional laser-based setup (LBS). Materials and Methods: Both tangential (63 patients) and locoregional (76 patients) breast cancer patients were enrolled in this study. For LBS, the patients were positioned by aligning skin markers to the room lasers. For the surface based setup (SBS), an optical surface scanning system was used for daily setup using both single and three camera systems. To compare the two setup methods, the patient position was evaluated using verification imaging (field images or orthogonal images). Results: For both tangential and locoregional treatments, SBS decreased the setup deviation significantly compared to LBS (P < 0.01). For patients receiving tangential treatment, 95% of the treatment sessions were within the clinical tolerance of ≤ 4 mm in any direction (lateral, longitudinal or vertical) using SBS, compared to 84% for LBS. Corresponding values for patients receiving locoregional treatment were 70% and 54% for SBS and LBS, respectively. No significant difference was observed comparing the setup result using a single camera system or a three camera system. Conclusions: Conventional laser-based setup can with advantage be replaced by surface based setup. Daily SGRT improves patient setup without additional imaging dose to breast cancer patients regardless if a single or three camera system was used.
|
|
| 8. |
- Larsson, Lena Gunvor, et al.
(författare)
-
A national study on collaboration in care planning for patients with complex needs
- 2019
-
Ingår i: International Journal of Health Planning and Management. - : Wiley. - 0749-6753 .- 1099-1751. ; 34:1, s. E646-E660
-
Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: The purpose of this study was to investigate inter-organisational collaboration on care planning for patients with complex care needs. Internationally, and in Sweden where the data for this study was collected, difficulties in care planning and transition of patients between the main health care providers, hospitals, municipal care, and primary care are well known.METHOD: A survey of a total population of care managers in hospitals, municipalities, and primary care in Sweden was conducted. The study assessed accessibility, willingness, trustworthiness, and collaboration between health care providers. Data were analysed with descriptive statistics, bivariate, and multivariate regressions.RESULTS: The results indicate that Swedish health care providers show strong self-awareness, but they describe each other's ability to collaborate as weak. Primary care stands out, displaying the highest discrepancy between self-awareness and displayed accessibility, willingness, trustworthiness, and collaboration.CONCLUSION: Inability to collaborate in patient care planning may be due to shortcomings in terms of trust between caregivers in the health care organisation at a national level. Organisations that experience difficulties in collaboration tend to defend themselves with arguments about their own excellence and insufficiency of others.
|
|
| 9. |
- Larsson, Lena Gunvor, et al.
(författare)
-
Primary care managers’ perceptions of their capability in providing care planning to patients with complex needs
- 2017
-
Ingår i: Health Policy. - : Elsevier BV. - 0168-8510 .- 1872-6054. ; 121:1, s. 58-65
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate primary care managers’ perceptions of their capability in providing care planning to patients with complex needs. Care planning is defined as a process where the patient, family and health professionals engage in dialogue about the patient's care needs and plan care interventions together. Methods Semi-structured interviews with 18 primary care managers in western Sweden were conducted using Westrin's theoretical cooperation model. Data were analysed using a qualitative deductive method. Main findings Results reveal that the managers’ approach to care planning was dominated by non-cooperation and separation. The managers were permeated by uncertainty about the meaning of the task of care planning as such. They did not seem to be familiar with the national legislation stipulating that every healthcare provider must meet patients’ need for care interventions and participate in the care planning. Implications for practice To accomplish care planning, the process needs to cross – and overcome – both professional and organisational boundaries. There is also a need for incentives to develop working methods that promote local cooperation in order to facilitate optimal care for patients with complex needs.
|
|
| 10. |
- Lempart, Michael, et al.
(författare)
-
Modifying a clinical linear accelerator for delivery of ultra-high dose rate irradiation
- 2019
-
Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140. ; 139, s. 40-45
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: The purpose of this study was to modify a clinical linear accelerator, making it capable of electron beam ultra-high dose rate (FLASH) irradiation. Modifications had to be quick, reversible, and without interfering with clinical treatments. Methods: Performed modifications: (1) reduced distance with three setup positions, (2) adjusted/optimized gun current, modulator charge rate and beam steering values for a high dose rate, (3) delivery was controlled with a microcontroller on an electron pulse level, and (4) moving the primary and/or secondary scattering foils from the beam path. Results: The variation in dose for a five-pulse delivery was measured to be 1% (using a diode, 4% using film) during 10 minutes after a warm-up procedure, later increasing to 7% (11% using film). A FLASH irradiation dose rate was reached at the cross-hair foil, MLC, and wedge position, with ≥30, ≥80, and ≥300 Gy/s, respectively. Moving the scattering foils resulted in an increased output of ≥120, ≥250, and ≥1000 Gy/s, at the three positions. The beam flatness was 5% at the cross-hair position for a 20 × 20 and a 10 × 10 cm2 area, with and without both scattering foils in the beam. The beam flatness was 10% at the wedge position for a 6 and 2.5 cm diametric area, with and without the scattering foils in the beam path. Conclusions: A clinical accelerator was modified to produce ultra-high dose rates, high enough for FLASH irradiation. Future work aims to fine-tune the dose delivery, using the on-board transmission chamber signal and adjusting the dose-per-pulse.
|
|
| 11. |
|
|
