| 1. |
- Alsadius, David, 1975, et al.
(författare)
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Mean Absorbed Dose to the Anal-Sphincter Region and Fecal Leakage among Irradiated Prostate Cancer Survivors.
- 2012
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 84:2
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To supplement previous findings that the absorbed dose of ionizing radiation to the anal sphincter or lower rectum affects the occurrence of fecal leakage among irradiated prostate-cancer survivors. We also wanted to determine whether anatomically defining the anal-sphincter region as the organ at risk could increase the degree of evidence underlying clinical guidelines for restriction doses to eliminate this excess risk. METHODS AND MATERIALS: We identified 985 men irradiated for prostate cancer between 1993 and 2006. In 2008, we assessed long-term gastrointestinal symptoms among these men using a study-specific questionnaire. We restrict the analysis to the 414 men who had been treated with external beam radiation therapy only (no brachytherapy) to a total dose of 70 Gy in 2-Gy daily fractions to the prostate or postoperative prostatic region. On reconstructed original radiation therapy dose plans, we delineated the anal-sphincter region as an organ at risk. RESULTS: We found that the prevalence of long-term fecal leakage at least once per month was strongly correlated with the mean dose to the anal-sphincter region. Examining different dose intervals, we found a large increase at 40 Gy; ≥40 Gy compared with <40 Gy gave a prevalence ratio of 3.8 (95% confidence interval 1.6-8.6). CONCLUSIONS: This long-term study shows that mean absorbed dose to the anal-sphincter region is associated with the occurrence of long-term fecal leakage among irradiated prostate-cancer survivors; delineating the anal-sphincter region separately from the rectum and applying a restriction of a mean dose <40 Gy will, according to our data, reduce the risk considerably.
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| 2. |
- Alsadius, David, 1975, et al.
(författare)
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Patient-reported gastrointestinal symptoms among long-term survivors after radiation therapy for prostate cancer.
- 2014
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 1879-0887. ; 112:2, s. 237-243
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Tidskriftsartikel (refereegranskat)abstract
- With modern radiotherapy technology we have the means to substantially reduce late gastrointestinal toxicities after radiation therapy for prostate cancer. However, there is still a lack of knowledge regarding the spectrum of patient-reported gastrointestinal symptoms after such treatment.
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| 3. |
- Alsadius, David, 1975, et al.
(författare)
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Perception of body odor-an overlooked consequence of long-term gastrointestinal and urinary symptoms after radiation therapy for prostate cancer.
- 2013
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Ingår i: Journal of cancer survivorship : research and practice. - : Springer Science and Business Media LLC. - 1932-2267. ; 7:4, s. 652-658
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Tidskriftsartikel (refereegranskat)abstract
- Purpose This study was conducted to investigate the association of long-term gastrointestinal and urinary symptoms with perceived fecal or urine body odor after radiation therapy for prostate cancer and its effect on survivors’ quality of life. Methods We used a study-specific questionnaire to measure the occurrence of long-term gastrointestinal and urinary symptoms, the perception of fecal or urine body odor, and quality of life (QoL) 2 to 14 years after radiation therapy for prostate cancer. The questionnaire was sent to 895 eligible survivors who assessed symptom occurrence and QoL in the previous 6 months. Results We received a filled-in questionnaire from 874 (89 %) men. For the long-term gastrointestinal symptoms, 11/13 were associated with the perception of fecal body odor. For the long-term urinary symptoms, 11/11 were associated with the perception of urine body odor. Men who perceived fecal or urine body odor had a lower quality of life, a lower physical health, and more frequent feelings of depression compared with those who did perceive such body odor. Conclusion Long-term gastrointestinal and urinary symptoms after prostate irradiation are associated with the perception of fecal or urine body odor leading to a reduced quality of life. Implications for cancer survivors Disabling body odor after pelvic irradiation needs to be acknowledged in the clinic. Interventions to prevent long-term symptoms may serve the benefit of avoiding fecal or urine body odor after radiation therapy for prostate cancer.
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| 4. |
- Alsadius, David, 1975, et al.
(författare)
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Tobacco smoking and long-lasting symptoms from the bowel and the anal-sphincter region after radiotherapy for prostate cancer.
- 2011
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 1879-0887.
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Tobacco smoking can cause vascular injury, tissue hypoxia and fibrosis as can ionizing radiation. However, we do not know if tobacco smoking increases the risk of long-term side effects after radiotherapy for prostate cancer. METHODS: We identified 985 men treated with radiotherapy for prostate cancer between 1993 and 2006. In 2008, long-lasting symptoms appearing after radiotherapy for prostate cancer were assessed through a study-specific questionnaire as were smoking habits and demographic factors of all these men. In the questionnaire the prostate-cancer survivors were asked to report symptom occurrence the previous six months. RESULTS: We obtained information on tobacco smoking from 836 of the 985 prostate-cancer survivors with a median time to follow-up of six years (range 2-14years). The prevalence ratio of defecation urgency among current smokers compared to never smokers was 1.6 (95% CI 1.2-2.2). Corresponding prevalence ratio for diarrhea was 2.8 (95% CI 1.2-6.5), the sensation of bowel not completely emptied after defecation 2.1 (95% CI 1.3-3.3) and for sudden emptying of all stools into clothing without forewarning 4.7 (95% CI 2.3-9.7). CONCLUSION: Tobacco smoking among prostate-cancer survivors treated with radiotherapy increases the risk of certain long-lasting symptoms from the bowel and anal-sphincter region.
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| 5. |
- Andersson, Patrik, et al.
(författare)
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Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry
- 2021
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Ingår i: Physica medica (Testo stampato). - : Associazione Italiana di Fisica Medica. - 1120-1797 .- 1724-191X. ; 90, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To investigate the sensitivity of Monte Carlo (MC) calculated lung dose distributions to lung tissue characterization in external beam radiotherapy of breast cancer under Deep Inspiration Breath Hold (DIBH). Methods: EGSnrc based MC software was employed. Mean lung densities for one hundred patients were analysed. CT number frequency and clinical dose distributions were calculated for 15 patients with mean lung density below 0.14 g/cm3. Lung volume with a pre-defined CT numbers was also considered. Lung tissue was characterized by applying different CT calibrations in the low-density region and air-lung tissue thresholds. Dose impact was estimated by Dose Volume Histogram (DVH) parameters. Results: Mean lung densities below 0.14 g/cm3 were found in 10% of the patients. CT numbers below −960 HU dominated the CT frequency distributions with a high rate of CT numbers at −990 HU. Mass density conversion approach influenced the DVH shape. V4Gy and V8Gy varied by 7% and 5% for the selected patients and by 9% and 3.5% for the pre-defined lung volume. V16Gy and V20Gy, were within 2.5%. Regions above 20 Gy were affected. Variations in air- lung tissue differentiation resulted in DVH parameters within 1%. Threshold at −990 HU was confirmed by the CT number frequency distributions. Conclusions: Lung dose distributions were more sensitive to variations in the CT calibration curve below lung (inhale) density than to air-lung tissue differentiation. Low dose regions were mostly affected. The dosimetry effects were found to be potentially important to 10% of the patients treated under DIBH.
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| 6. |
- Beasley, W., et al.
(författare)
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Image-based Data Mining to Probe Dosimetric Correlates of Radiation-induced Trismus
- 2018
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Ingår i: International Journal of Radiation Oncology Biology Physics. - : Elsevier BV. - 0360-3016. ; 102:4, s. 1330-1338
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To identify imaged regions in which dose is associated with radiation-induced trismus after head and neck cancer radiation therapy (HNRT) using a novel image-based data mining (IBDM) framework. Methods and Materials: A cohort of 86 HNRT patients were analyzed for region identification. Trismus was characterized as a continuous variable by the maximum incisor-to-incisor opening distance (MID) at 6 months after radiation therapy. Patient anatomies and dose distributions were spatially normalized to a common frame of reference using deformable image registration. IBDM was used to identify clusters of voxels associated with MID (P <= .05 based on permutation testing). The result was externally tested on a cohort of 35 patients with head and neck cancer. Internally, we also performed a dose-volume histogram-based analysis by comparing the magnitude of the correlation between MID and the mean dose for the IBDM-identified cluster in comparison with 5 delineated masticatory structures. Results: A single cluster was identified with the IBDM approach (P < .01), partially overlapping with the ipsilateral masseter. The dose-volume histogram-based analysis confirmed that the IBDM cluster had the strongest association with MID, followed by the ipsilateral masseter and the ipsilateral medial pterygoid (Spearman's rank correlation coefficients: R-s = -0.36, -0.35, -0.32; P = .001, .001, .002, respectively). External validation confirmed an association between mean dose to the IBDM cluster and MID (R-s = -0.45; P = .007). Conclusions: IBDM bypasses the common assumption that dose patterns within structures are unimportant. Our novel IBDM approach for continuous outcome variables successfully identified a cluster of voxels that are highly associated with trismus, overlapping partially with the ipsilateral masseter. Tests on an external validation cohort showed an even stronger correlation with trismus. These results support use of the region in HNRT treatment planning to potentially reduce trismus. (C) 2018 Elsevier Inc. All rights reserved.
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| 7. |
- Braide, Karin, et al.
(författare)
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Salvage radiation therapy in prostate cancer: relationship between rectal dose and long-term, self-reported rectal bleeding
- 2021
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Ingår i: Clinical & Translational Oncology. - : Springer Science and Business Media LLC. - 1699-048X .- 1699-3055. ; 23:2, s. 397-404
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To quantify the relationship between the rectal dose distribution and the prevalence of self-reported rectal bleeding among men treated with salvage radiotherapy (ST) delivered by three-dimensional conformal radiotherapy (3DCRT) for prostate cancer. To use this relationship to estimate the risk of rectal bleeding for a contemporary cohort of patients treated with volumetric modulated arc therapy (VMAT) ST. Methods and patients Rectal bleeding of any grade was reported by 56 (22%) of 255 men in a PROM-survey at a median follow-up of 6.7 years after 3DCRT ST. Treatment plan data were extracted and dose-response relationships for the rectal volumes receiving at least 35 Gy (V-35Gy) or 63 Gy (V-63Gy) were calculated with logistic regression. These relationships were used to estimate the risk of rectal bleeding for a cohort of 253 patients treated with VMAT ST. Results In the dose-response analysis of patients in the 3DCRT ST cohort, both rectal V(35Gy)and V(63Gy)were statistically significant parameters in univariable analysis (p = 0.005 and 0.003, respectively). For the dose-response models using either rectal V(35Gy)or V-63Gy, the average calculated risk of rectal bleeding was 14% among men treated with VMAT ST compared to a reported prevalence of 22% for men treated with 3DCRT ST. Conclusions We identified dose-response relationships between the rectal dose distribution and the risk of self-reported rectal bleeding of any grade in a long-term perspective for men treated with 3DCRT ST. Furthermore, VMAT ST may have the potential to decrease the prevalence of late rectal bleeding.
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| 8. |
- Breen, Sinéad, et al.
(författare)
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A study of students’ concept images of inverse functions in Ireland and Sweden
- 2017
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Ingår i: Nordisk matematikkdidaktikk, NOMAD. - 1104-2176. ; 22:4, s. 85-102
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we focus on first-year university students’ conceptions of inverse function. We present results from two projects, conducted in Ireland and Sweden respectively. In both countries, data were collected through questionnaires, as well as through student interviews in Sweden. We draw on the notion of concept image and describe the components of students’ evoked concept images. The students’ responses involved e.g. ”reflection”, ”reverse”, and concrete ”examples”, while just a few students gave explanations relating to the definition of inverse functions. We found that the conceptions of inverses as reflections and reverse processes are important and relatively independent of local factors, and the data seemed to suggest that a ”reverse” conception is linked to an appreciation of injectivity more than a ”reflection” conception.
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| 9. |
- Cervino, L. I., et al.
(författare)
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An in vitro study for the dosimetric and radiobiological validation of respiratory gating in conventional and hypofractionated radiotherapy of the lung: effect of dose, dose rate, and breathing pattern
- 2019
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 64:13
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Tidskriftsartikel (refereegranskat)abstract
- Stereotactic body radiotherapy (SBRT) of the lung has become a standard of care for early-stage inoperable non-small cell lung cancer (NSCLC). A common strategy to manage respiratory motion is gating, which inevitably results in an increase in treatment time, especially in irregularly-breathing patients. Flattening-filter free (FFF) beams allow for delivery of the treatment at a higher dose rate, therefore counteracting the lengthened treatment time due to frequent interruption of the beam during gated radiotherapy. In this study, we perform our in vitro evaluation of the dosimetric and radiobiological effect of gated lung SBRT with simultaneous integrated boost (SIB) using both flattened and FFF beams. A moving thorax-shaped phantom with inserts and applicators was used for simulation, planning, gated treatment delivery measurements and in vitro tests. The effects of gating window, dose rate, and breathing pattern were evaluated. Planned doses represented a typical conventional fractionation, 200 cGy per fraction with SIB to 240 cGy, flattened beam only, and SBRT, 800 cGy with SIB to 900 cGy, flattened and FFF beams. Ideal, as well as regular and irregular patient-specific breathing patterns with and without gating were used. A survival assay for lung adenocarcinoma A549 cell line was performed. Delivered dose was within 6% for locations planned to receive 200 and 800 cGy and within 4% for SIB locations. Time between first beam-on and last beam-off varied from approximately 1.5 min for conventional fractionation, 200/240 cGy, to 10.5 min for gated SBRT, 800/900 cGy doses, flattened beam and irregular breathing motion pattern. With FFF beams dose delivery time was shorter by a factor of 2-3, depending on the gating window and breathing pattern. We have found that, for the most part, survival depended on dose and not on dose rate, gating window, or breathing regularity.
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| 10. |
- Choudhary, Vipin
(författare)
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Nondestructive testing and antenna measurements using UWB radar in industrial applications
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many industries are rapidly substituting the manual test operations and move towards automated operations using modern technologies.Modern technologies such as digital cameras, sonic sensors, infrared sensors, and radar and lidar systems are used for non-destructive testingoperations. Among all the different sensors, radar systems have theability to penetrate built structures (dielectric materials), which makes them flexible and suitable for a wide range of industrial and military applications in non-destructive sensing. Such examples are the detection of damages in goods manufacturing, monitoring the health of manystructures, object detection through the wall for security purposes, etc.In particular, ultra-wide-band (UWB) radar systems are beneficial inproviding high measurement accuracy and simultaneously reduced sensitivityto passive interference (such as rain, smoke, mist etc.), immunity to external radiation and noise.The objectives of this thesis are: I) to investigate electrically small concealed structures using synthetic aperture radar (SAR), II) to determinethe complex refractive index of objects using an UWB radar system,and III) to answer to the question how we can reduce the mutual coupling (cross talk) in an UWB radar system with collocated transmitand receive antennae. In objective I, the aim is non-destructive testing of built structures, such as in concrete slab manufacturing or for use in the renovation process. In addition electrically small periodic meshes,and their orientation, could not be distinguished in conventional SAR images. The proposed polarimetric analysis method demonstrates the usefulness of the singular value decomposition (SVD) using back projection algorithm (BPA) in extracting information about shape and for classifying an electrically small object. Further in this thesis for objective II, a new method for determining the complex refractive index (or equivalently the complex relative permittivity) of objects with planar interfaces is presented. The proposed method is relatively insensitive to hardware-impairments such as frequency-dependence of antennas and analog front end. The objects can be finite in size and at a finite distance. The limits in size and distance for the method to be valid are experimentally investigated. Hence, the method is designed for industrial in-line measurements onobjects on conveyor belts. Furthermore, in the following parts of this thesis −objective III− we investigate and show how a microwave metamaterial based absorber can be used to improve the performance of aradar system for short range applications, when positioned between the transmit and receive antennas. As results, the error in estimated target distance is reduced and clutter reduction is improved.
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