| 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. |
- 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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| 6. |
- 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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| 7. |
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| 8. |
- Moiseenko, Vitali, et al.
(författare)
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A Primer on Dose-Response Data Modeling in Radiation Therapy.
- 2021
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 110:1, s. 11-20
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Tidskriftsartikel (refereegranskat)abstract
- An overview of common approaches used to assess a dose response for radiation therapy-associated endpoints is presented, using lung toxicity data sets analyzed as a part of the High Dose per Fraction, Hypofractionated Treatment Effects in the Clinic effort as an example. Each component presented (eg, data-driven analysis, dose-response analysis, and calculating uncertainties on model prediction) is addressed using established approaches. Specifically, the maximum likelihood method was used to calculate best parameter values of the commonly used logistic model, the profile-likelihood to calculate confidence intervals on model parameters, and the likelihood ratio to determine whether the observed data fit is statistically significant. The bootstrap method was used to calculate confidence intervals for model predictions. Correlated behavior of model parameters and implication for interpreting dose response are discussed.
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| 9. |
- Mövik, Louise, 1993, et al.
(författare)
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Impact of delineation errors on the estimated organ at risk dose and of dose errors on the normal tissue complication probability model
- 2023
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Ingår i: Medical Physics. - : Wiley. - 0094-2405 .- 2473-4209. ; 50:3, s. 1879-1892
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Tidskriftsartikel (refereegranskat)abstract
- Background: Normal tissue complication probability (NTCP) models are often based on doses retrieved from delineated volumes. For retrospective dose-response studies focusing on organs that have not been delineated historically, automatic segmentation might be considered. However, automatic segmentation risks generating considerable delineation errors and knowledge regarding how these errors impact the estimated organ dose is important. Furthermore, organ-at-risk (OAR) dose uncertainties cannot be eliminated and might affect the resulting NTCP model. Therefore, it is also of interest to study how OAR dose errors impact the NTCP modeling results. Purpose: To investigate how random delineation errors of the proximal bronchial tree, heart, and esophagus impact the estimated OAR dose, and to investigate how random errors in the doses used for dose-response modeling affect the estimated NTCPs. Methods: We investigated the impact of random delineation errors on the estimated OAR dose using the treatment plans of 39 patients treated with conventionally fractionated radiation therapy of non-small-cell lung cancer. Study-specific reference structures were defined by manually contouring the proximal bronchial tree, heart and esophagus. For each patient and organ, 120 reshaped structures were created by introducing random shifts and margins to the entire reference structure. The mean and near-maximum dose to the reference and reshaped structures were compared. In a separate investigation, the impact of random dose errors on the NTCP model was studied performing dose-response modeling with study sets containing treatment outcomes and OAR doses with and without introduced errors. Universal patient populations with defined population risks, dose-response relationships and distributions of OAR doses were used as ground truth. From such a universal population, we randomly sampled data sets consisting of OAR dose and treatment outcome into reference populations. Study sets of different sizes were created by repeatedly introducing errors to the OAR doses of each reference population. The NTCP models generated with dose errors were compared to the reference NTCP model of the corresponding reference population. Results: A total of 14 040 reshaped structures with random delineation errors were created. The delineation errors resulted in systematic mean dose errors of less than 1% of the prescribed dose (PD). Mean dose differences above 15% of PD and near-maximum doses differences above 25% of PD were observed for 211 and 457 reshaped structures, respectively. Introducing random errors to OAR doses used for dose-response modeling resulted in systematic underestimations of the median NTCP. For all investigated scenarios, the median differences in NTCP were within 0.1 percentage points (p.p.) when comparing different study sizes. Conclusions: Introducing random delineation errors to the proximal bronchial tree, heart and esophagus resulted in mean dose and near-maximum dose differences above 15% and 25% of PD, respectively. We did not observe an association between the dose level and the magnitude of the dose errors. For the scenarios investigated in this study, introducing random errors to OAR doses used for dose-response modeling resulted in systematic underestimations of the median NTCP for reference risks higher than the universal population risk. The median NTCP underestimation was similar for different study sizes, all within 0.1 p.p.
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| 10. |
- Olsson, C. E., et al.
(författare)
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Feasibility of Mastication-Structure-Sparing Radiotherapy for Head and Neck Cancer
- 2021
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Ingår i: International journal of radiation oncology, biology, physics. - : Elsevier BV. - 1879-355X .- 0360-3016. ; 111:3
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE/OBJECTIVE(S): Although radiation-induced side-effects affecting mastication functionality have been studied in head and neck cancer (HNC) radiotherapy (RT), dose constraints for the associated structures are rarely included during treatment plan optimization. Previous research has identified several radiation dose relationships with mean dose thresholds around 30-40 Gy for masseter muscles, 40-50 Gy for pterygoid muscles, and 15-60 Gy for temporomandibular joint (TMJ) relating to a 10% trismus risk post RT. The purpose of this work was to use a multi-criteria optimization (MCO) approach to investigate to what extent doses to these structures can be lowered without violating existing clinical treatment goals in inverse planning of HNC RT. MATERIALS/METHODS: This exploratory treatment planning study used data from 22 HNC patients treated to 68 Gy without mastication-structure-sparing intent in 2017-2019 at one institute in Sweden. Original volumetric-modulated arc therapy (VMAT) plans were re-activated in the treatment planning system and masseter muscles, pterygoid muscles (medial and lateral), and TMJ were consistently delineated according to a previously reported delineation manual4. Re-planning was done using the MCO function of the treatment planning system with the resulting dose distribution normalized to match the clinical target volume (CTV T) mean dose of the clinical treatment plan. Dose differences between MCO and clinical plans were not allowed to exceed 2 Gy for any original clinical treatment goal unless tolerance doses had been substantially exceeded in the clinical treatment plan. To what extent dose to mastication structures could be lowered without violating existing clinical treatment goals were quantified by group and by patient. RESULTS: Altogether, there were 334 clinical treatment goals in the clinical treatment plans (median=15, range: 7-24 per patient, depending on tumor location), which easily could be met in the corresponding MCO plans. Mean doses to the mastication structures were in most cases below proposed tolerance doses in the clinical plan but could on average be further reduced between 3-5 Gy in the MCO plans (Table). Of the 25/88 patient reductions below 5 Gy (28%), 18/25 (72%) were for the masseter (n=8) and medial pterygoid (n=10) muscles. CONCLUSION: With modern RT, it seems possible to reduce the dose to mastication structures below proposed trismus dose tolerance thresholds for most HNC patients without violating clinical treatment goals. Focusing on masseter and medial pterygoid muscle doses may prove to give the largest benefit in individual cases. Copyright © 2021. Published by Elsevier Inc.
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| 11. |
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| 12. |
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| 13. |
- Pettersson, Niclas, 1974, et al.
(författare)
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A method to estimate composite doses for organs at risk in prostate cancer patients treated with EBRT in combination with HDR BT.
- 2014
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Ingår i: Acta oncologica (Stockholm, Sweden). - 1651-226X. ; 53:6, s. 815-821
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Tidskriftsartikel (refereegranskat)abstract
- Background. When evaluating late toxicity after combined external beam radiation therapy (EBRT) and high-dose rate brachytherapy (HDR BT) prostate cancer treatments, it is important that the composite dose distribution is taken into account. This can be challenging if organ-at-risk (OAR) dose data are incomplete, i.e. due to a limited ultrasound imaging field-of-view in the HDR BT procedure. This work proposes a method that provides estimates of composite OAR doses for such situations. Material and methods. Original EBRT, simulated HDR BT, and composite dose-volume histograms (DVHs) for 10 pelvic OARs in 30 prostate cancer cases were used for method implementation and evaluation (EBRT: 25 × 2.0 Gy + BT: 2 × 10.0 Gy). The proposed method used information from the EBRT DVH to estimate OAR BT doses (with or without fractionation correction). Coefficients of determination (R(2)) were calculated for linear relationships between several EBRT DVH parameters and a BT DVH parameter of interest. The largest R(2) value decided the relationship that best predicted the BT DVH parameter. The composite dose value was then calculated by adding the EBRT DVH and the estimated BT DVH parameter values and was compared to the reference composite value (in 1200 OAR/patient/parameter cases). Results. The linear relationships had an average R(2) of 0.68 (range 0.42-0.88). Only one ninth of the 1200 estimated composite DVH values differed more than 2 Gy from their reference values. Conclusion. Given a successful implementation, the proposed method only requires original or simulated BT plan data for a subset of patients to estimate composite doses for large study populations in a time-efficient manner. This can assist in evaluating radiation-induced late toxicity in multimodality treatments with limited OAR dose data.
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| 14. |
- Pettersson, Niclas, 1974, et al.
(författare)
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Intrafractional relationship changes between an external breathing signal and fiducial marker positions in pancreatic cancer patients
- 2020
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Ingår i: Journal of Applied Clinical Medical Physics. - : Wiley. - 1526-9914. ; 21:3, s. 153-161
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose The purpose of this study of pancreatic cancer patients treated with respiratory-guided stereotactic body radiotherapy (SBRT) on a standard linac was to investigate (a) the intrafractional relationship change (IRC) between a breathing signal and the tumor position, (b) the impact of IRC on the delivered dose, and (c) potential IRC predictors. Materials and methods We retrospectively investigated 10 pancreatic cancer patients with 2-4 implanted fiducial markers in the tumor treated with SBRT. Fluoroscopic images were acquired before and after treatment delivery simultaneously with the abdominal breathing motion. We quantified the IRC as the change in fiducial location for a given breathing amplitude in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions from before to after treatment delivery. The treatment plans were re-calculated after changing the isocenter coordinates according to the IRCs. Four treatment- or patient-related factors were investigated as potential predictors for IRC using linear models. Results The average (+/- 1 SD) absolute IRCs in the LR, AP, and SI directions were 1.2 +/- 1.2 mm, 0.7 +/- 0.7 mm, and 1.1 +/- 0.8 mm, respectively. The average 3D IRC was 2.0 +/- 1.3 mm (range: 0.4-5.3 mm) for a median treatment delivery time of 8.5 min (range: 5.7-19.9 min; n = 31 fractions). The dose coverage of the internal target volume (ITV) decreased by more than 3% points in three of 31 fractions. In those cases, the 3D IRC had been larger than 4.3 mm. The 3D IRC was found to correlate with changes in the minimum breathing amplitude during treatment delivery. Conclusion On average, 2 mm of treatment delivery accuracy was lost due to IRC. Periodical intrafractional imaging is needed to safely deliver respiratory-guided SBRT.
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| 15. |
- Pettersson, Niclas, 1974
(författare)
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Modelling late toxicity in hypofractionated radiation therapy
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In hypofractionated radiation therapy (RT), the treatment is delivered by few fractions with high doses per fraction. This is in contrast to conventionally fractionated RT where the total dose is delivered in many fractions with low doses per fraction. Hypofractionation is increasingly used in RT for small tumour volumes, but knowledge about radiation-induced tox¬icity in healthy tissue (organs at risk, OARs) and suitable methods for modelling toxicity in this specific situation is limited. The aim of this thesis is to investigate radiation-induced toxicity in normal tissue caused by hypofractionated RT through the development of modelling methods and their applications to clinical data. Particular emphasis will be on the fractionation effect. The thesis treats theoretical and practical aspects of normal tissue complication probability (NTCP) modelling such as radiobiologically consistent dose-response curves, how to estimate composite doses in combined radiation therapy with limited treatment information and how to manage situations where non-treatment-related factors contribute to a studied toxicity. The thesis also discusses how fractionation effects as described by the linear-quadratic model may affect the modelling procedure and the modelling results. The clinical applications involve two datasets with non-small-cell lung cancer (NSCLC) patients (n=26) or localized prostate cancer patients (n=874). Patients were consecutively treated at the Sahlgrenska University Hospital in Göteborg, Sweden, 1998-2005 and 1993-2006, respectively. The first paper presents NTCP modelling results for radiation-induced rib fractures after hypofractionated SBRT for NSCLC. The results indicate that the high-dose region is more strongly asso¬ciated with rib fracture than a low dose in a large volume. The second paper presents a survey of 21 patient-reported genitourinary symptoms among prostate cancer survivors. The toxicity profile for survivors treated with the combination of conventionally fractionated external beam radiation therapy (EBRT) and hypofractionated brachytherapy (EBRT+BT) is similar to the toxicity profile for survivors treated with convention¬ally fractionated EBRT. The third paper investigates urethral pain among prostate cancer survivors and finds that higher fractionation-corrected urethral dose corresponds to higher prevalence; no such relationship is seen for absorbed dose. Survivors with three years to follow-up report urethral pain more fre¬quently than survivors with more than three years to follow-up. The fourth paper suggests a method to estimate composite doses in pelvic OARs after prostate cancer EBRT+BT with limited treatment information. It was motivated by the lack of BT dose information in the prostate cancer dataset. The method produces robust estimations for OARs located far from the prostate, but estimations for OARs located close to the prostate may be less robust. The fifth paper presents a relationship between mean urinary bladder dose (with or without frac¬tionation correction) and urinary leakage for men treated with EBRT. Analyses are performed for survivors treated with EBRT and EBRT+BT separately as well as for the whole study population. Symptom background rates from non-irradiated controls were considered. Estimated composite urinary bladder doses by the method suggested in Paper IV are used for the EBRT+BT group.
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| 16. |
- Pettersson, Niclas, 1974, et al.
(författare)
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Radiation-induced rib fractures after hypofractionated stereotactic body radiation therapy of non-small cell lung cancer: a dose- and volume-response analysis.
- 2009
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 1879-0887. ; 91:3, s. 360-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: The aim of this study is to analyse the dose-response and the volume-response of radiation-induced rib fractures after hypofractionated stereotactic body radiation therapy (SBRT). MATERIALS AND METHODS: During the period 1998-2005, 68 patients with medically inoperable stage I non-small cell lung cancer (NSCLC) were treated with hypofractionated SBRT to 45 Gy in 3 fractions. Among the 33 patients with complete treatment records and radiographic follow-up exceeding 15 months (median: 29 months), 13 fractures were found in seven patients. Identifying all ribs receiving at least 21 Gy, 81 ribs (13 with and 68 without fracture) in 26 patients were separately contoured and their dose-volume histograms (DVHs) were obtained. The DVHs were assessed with the mean dose and cut-off models. Maximum likelihood estimation was used to fit dose-response and volume-response curves to each model. RESULTS: It was possible to quantify the risk of radiation-induced rib fracture using response curves and information contained in the DVHs. Absolute volumes provided better fits than relative volumes and dose-response curves were more suitable than volume-response curves. For the dose given by the 2 cm(3) cut-off volume, D(2 cm(3)), the logistic dose-response curve for three fractions was parameterised by D(50)=49.8 Gy and gamma(50)=2.05. Consequently, for a median follow-up of 29 months, if D(2 cm(3))<3 x 7.0 Gy the risk is close to 0, and the 5% and 50% risks are given by D(2 cm(3))=3 x 9.1 Gy and 3 x 16.6 Gy, respectively. CONCLUSIONS: In this group of patients, the risk for radiation-induced rib fracture following hypofractionated SBRT was related to the dose to 2 cm(3) of the rib.
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| 17. |
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| 18. |
- Polymeri, Erini, et al.
(författare)
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Artificial Intelligence-Based Organ Delineation for Radiation Treatment Planning of Prostate Cancer on Computed Tomography
- 2024
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Ingår i: Advances in Radiation Oncology. - 2452-1094. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Meticulous manual delineations of the prostate and the surrounding organs at risk are necessary for prostate cancer radiation therapy to avoid side effects to the latter. This process is time consuming and hampered by inter- and intraobserver variability, all of which could be alleviated by artificial intelligence (AI). This study aimed to evaluate the performance of AI compared with manual organ delineations on computed tomography (CT) scans for radiation treatment planning. Methods and Materials: Manual delineations of the prostate, urinary bladder, and rectum of 1530 patients with prostate cancer who received curative radiation therapy from 2006 to 2018 were included. Approximately 50% of those CT scans were used as a training set, 25% as a validation set, and 25% as a test set. Patients with hip prostheses were excluded because of metal artifacts. After training and fine-tuning with the validation set, automated delineations of the prostate and organs at risk were obtained for the test set. Sørensen-Dice similarity coefficient, mean surface distance, and Hausdorff distance were used to evaluate the agreement between the manual and automated delineations. Results: The median Sørensen-Dice similarity coefficient between the manual and AI delineations was 0.82, 0.95, and 0.88 for the prostate, urinary bladder, and rectum, respectively. The median mean surface distance and Hausdorff distance were 1.7 and 9.2 mm for the prostate, 0.7 and 6.7 mm for the urinary bladder, and 1.1 and 13.5 mm for the rectum, respectively. Conclusions: Automated CT-based organ delineation for prostate cancer radiation treatment planning is feasible and shows good agreement with manually performed contouring.
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| 19. |
- Stervik, Louise, 1993, et al.
(författare)
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Modelling the risk of fatal acute toxicity following radiotherapy of lung cancer
- 2018
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Ingår i: Physica medica. Vol. 52, Suppl. 1, p. 30. 2nd European Congress of Medical Physics. - : Elsevier BV. - 1120-1797 .- 1724-191X.
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Konferensbidrag (refereegranskat)abstract
- Purpose:To model the risk of fatal acute toxicity after conventionally fractionated curative radiotherapy of patients with non-small-cell lung cancer (NSCLC). Methods:Scripting was used to automatically extract treatment-related data for all patients treated for NSCLC between 2008 and 2016 from three hospitals. Inclusion criteria were conventionally fractionated curative radiotherapy and no prior treatment in the thorax region. Maximum likelihood estimation and logistic regression (LR) were used to model the risk of fatal acute toxicity defined as death within 90 days from treatment start. Mean lung dose (MLD), patient age and the volume of the gross tumour volume (GTV) were investigated as predictors in a univariable LR analysis. We performed analysis on the data from the three hospitals separately and merged. Predictor variables were considered statistically significant if p < 0.05. All predictor variables with a p < 0.1 were further analysed in multivariable LR models. Confidence intervals (CIs) for the predictors were calculated using the likelihood ratio test. CIs for the multivariable models were calculated by bootstrapping. Results:Data was extracted for 848 patients. The incidence of death within 90 days from treatment start was 3.8% (32/848) for the merged data set and varied from 1.8% to 5.4% between hospitals. For the hospital with the highest incidence, a statistically significant relationship between MLD and the risk of fatal acute toxicity (p = 0.020) was found. The model parameters and their 95% CIs were D50=42.8 (31.4-167.7) Gy and γ50=1.20 (0.77-1.68). In the univariable LRs with patient age and GTV volume, patient age had p-values < 0.1 and GTV volume p-values > 0.2. Multivariable LR with MLD and patient age resulted in a statistically significant multivariable model (p = 0.005) for the merged data. The calculated risks and their 95% CIs for a patient with MLD = 20 Gy were 1.6% (0.5-3.3%), 2.8% (1.3-4.5%), 4.9% (3.1-6.8%), and 8.6% (4.8-13.5%) at 50, 60, 70, and 80 years of age, respectively. Conclusions:A statistically significant multivariable model quantifying the risk of fatal acute toxicity with MLD and patient age as predictor variables was found.
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| 20. |
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| 21. |
- Taheri-Kadkhoda, Zahra, 1969, et al.
(författare)
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Superiority of intensity-modulated radiotherapy over three-dimensional conformal radiotherapy combined with brachytherapy in nasopharyngeal carcinoma: a planning study.
- 2008
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Ingår i: The British journal of radiology. - : British Institute of Radiology. - 1748-880X .- 0007-1285. ; 81:965, s. 397-405
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Tidskriftsartikel (refereegranskat)abstract
- A planning study was performed in order to investigate the potential benefits of intensity-modulated radiotherapy using a simultaneous integrated multi-target treatment technique (SIMT-IMRT) over highly optimized three-dimensional conformal radiotherapy combined with intracavitary brachytherapy (3D-CRT + IBT) for the treatment of nasopharyngeal carcinoma (NPC). The subjects were eight patients with Stages I-IV NPC. For each case, two sets of plans were prepared after delineation of gross tumour volumes, three planning target volumes (PTVs) and 17 organs at risk (OARs). Dose prescriptions for PTVs were 72.6 Gy, 66 Gy and 52.8 Gy in 33 fractions for SIMT-IMRT vs 72 Gy (66 Gy in 33 fractions for 3D-CRT and 3 Gy twice for IBT), 66 Gy (in 33 fractions) and 46 Gy (in 23 fractions) for 3D-CRT + IBT plans. Compared with the combined plans, SIMT-IMRT provided superior results for the primary tumour (PT) in terms of mean equivalent uniform dose (67 Gy vs 63.7 Gy, p = 0.016). IMRT plans increased the mean tumour control probability (TCP) values (both uncorrected and corrected for accelerated tumour repopulation after 28 days) for PT when compared with 3D-CRT + IBT (98% and 94.3% vs 95.8% and 89.9%, respectively, p = 0.016). Mean doses to middle/external ears, parotid glands and temporomandibular joints were significantly lower in IMRT plans. Our conclusion is that, for all stages of NPC, SIMT-IMRT was superior to highly optimized 3D-CRT + IBT in terms of tumour coverage, increased local TCP, and dose reduction to some OARs. We recommend that SIMT-IMRT should be considered as a first-line radiotherapy technique for NPC.
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| 22. |
- Thor, Maria, et al.
(författare)
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Radiation Dose to the Penile Structures and Patient-Reported Sexual Dysfunction in Long-Term Prostate Cancer Survivors.
- 2015
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Ingår i: The journal of sexual medicine. - : Oxford University Press (OUP). - 1743-6109 .- 1743-6095. ; 12:12, s. 2388-2397
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Tidskriftsartikel (refereegranskat)abstract
- The involvement of various penile structures in radiotherapy (RT)-induced sexual dysfunction among prostate cancer survivors remains unclear and domains beyond erectile dysfunction such as orgasm, and pain have typically not been considered. The purpose of this study was to investigate sexual dysfunction post-RT for localized prostate cancer and to examine whether radiation dose to different penile structures can explain these symptoms.
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| 23. |
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| 24. |
- Thor, Maria, et al.
(författare)
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Urinary bladder dose-response relationships for patient-reported genitourinary morbidity domains following prostate cancer radiotherapy.
- 2016
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Ingår i: Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology. - : Elsevier BV. - 1879-0887. ; 119:1, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- Radiotherapy (RT) induced genitourinary (GU) morbidity is typically assessed by physicians as single symptoms or aggregated scores including symptoms from various domains. Here we apply a method to group patient-reported GU symptoms after RT for localized prostate cancer based on their interplay, and study how these relate to urinary bladder dose.
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| 25. |
- Waldenström, Ann-Charlotte, 1950, et al.
(författare)
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Variation in position and volume of organs at risk in the small pelvis.
- 2010
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Ingår i: Acta oncologica (Stockholm, Sweden). - : Informa UK Limited. - 1651-226X .- 0284-186X. ; 49:4, s. 491-9
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Tidskriftsartikel (refereegranskat)abstract
- In preparation for studies of dose volume of ionizing radiation and long-term side effects, we assessed both variation in position and volume of organs at risk in the small pelvis.
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