Aims: Stereotactic arrhythmia radiotherapy (STAR) is suggested as potentially effective and safe treatment for patients with therapy-refractory ventricular tachycardia (VT). However, the current... Show moreAims: Stereotactic arrhythmia radiotherapy (STAR) is suggested as potentially effective and safe treatment for patients with therapy-refractory ventricular tachycardia (VT). However, the current prospective knowledge base and experience with STAR is limited. In this study we aimed to prospectively evaluate the efficacy and safety of STAR. Methods and results: The StereoTactic Arrhythmia Radiotherapy in the Netherlands no.1 was a pre-post intervention study to prospectively evaluate efficacy and safety of STAR. In patients with therapy-refractory VT, the pro-arrhythmic region was treated with a 25 Gy single radiotherapy fraction. The main efficacy measure was a reduction in the number of treated VT-episodes by >= 50%, comparing the 12 months before and after treatment (or end of follow-up, excluding a 6-week blanking period). The study was deemed positive when >= 50% of patients would meet this criterion. Safety evaluation included left ventricular ejection fraction, pulmonary function, and adverse events. Six male patients with an ischaemic cardiomyopathy were enrolled, and median age was 73 years (range 54-83). Median left ventricular ejection fraction was 38% (range 24-52). The median planning target volume was 187 mL (range 93-372). Four (67%) patients completed the 12-month follow-up, and two patients died (not STAR related) during follow-up. The main efficacy measure of >= 50% reduction in treated VT-episodes at the end of follow-up was achieved in four patients (67%). The median number of treated VT-episodes was reduced by 87%. No reduction in left ventricular ejection fraction or pulmonary function was observed. No treatment related serious adverse events occurred. Conclusions: STAR resulted in a >= 50% reduction in treated VT-episodes in 4/6 (67%) patients. No reduction in cardiac and pulmonary function nor treatment-related serious adverse events were observed during follow-up. Show less
Purpose: Late radiation toxicity is a major dose-limiting factor in curative cancer radiation therapy. Previous studies identified several risk factors for late radiation toxicity, including both... Show morePurpose: Late radiation toxicity is a major dose-limiting factor in curative cancer radiation therapy. Previous studies identified several risk factors for late radiation toxicity, including both dose-volume factors and genetic predisposition. Herein, we investigated the contribution of genetic predisposition, particularly compared with dose-volume factors, to the risk of late radiation toxicity in patients treated with highly conformal radiation therapy. Methods and Materials: We included 179 patients with prostate cancer who underwent treatment with curative external beam radiation therapy between 2009 and 2013. Toxicity was graded according to the Common Terminology Criteria for Adverse Events version 4.0. Transcriptional responsiveness of homologous recombination repair genes and g-H2AX foci decay ratios (FDRs) were determined in ex vivo irradiated lymphocytes in a previous analysis. Dose-volume parameters were retrieved by delineating the organs at risk (OARs) on CT planning images. Associations between risk factors and grade >= 2 urinary and were performed using the highest toxicity grade recorded during the follow-up per patient. Results: The median follow-up period was 31 months. One hundred and one patients (56%) developed grade >2 late radiation toxicity. Cumulative rates for urinary and bowel grade >2 late toxicities were 46% and 17%, respectively. In the multivariable analysis, factors significantly associated with grade >2 late toxicity were transurethral resection of the prostate (P = .013), y-H2AX FDR <3.41 (P = .008), and rectum V70 >11.52% (P = .017). Conclusions: Our results suggest that impaired DNA double-strand break repair in lymphocytes, as quantified by y-H2AX FDR, is the most critical determining factor of late radiation toxicity. The limited influence of dose-volume parameters could be due to the use of increasingly conformal techniques, leading to improved dose-volume parameters of the organs at risk. = 2021 Elsevier Inc. All rights reserved. Show less
Youssef, A.; Hoorn, M.L.P. van der; Dongen, M.; Visser, J.; Bloemenkamp, K.; Lith, J. van; ... ; Lashley, E.E.L.O. 2021
Study question: What is the predictive performance of a currently recommended prediction model in an external Dutch cohort of couples with unexplained recurrent pregnancy loss (RPL)?Summary answer: .. Show moreStudy question: What is the predictive performance of a currently recommended prediction model in an external Dutch cohort of couples with unexplained recurrent pregnancy loss (RPL)?Summary answer: The model shows poor predictive performance on a new population; it overestimates, predicts too extremely and has a poor discriminative ability.What is known already: In 50-75% of couples with RPL, no risk factor or cause can be determined and RPL remains unexplained. Clinical management in RPL is primarily focused on providing supportive care, in which counselling on prognosis is a main pillar. A frequently used prediction model for unexplained RPL, developed by Brigham et al. in 1999, estimates the chance of a successful pregnancy based on number of previous pregnancy losses and maternal age. This prediction model has never been externally validated.Study design, size, duration: This retrospective cohort study consisted of 739 couples with unexplained RPL who visited the RPL clinic of the Leiden University Medical Centre between 2004 and 2019.Participants/materials, setting, methods: Unexplained RPL was defined as the loss of two or more pregnancies before 24 weeks, without the presence of an identifiable cause for the pregnancy losses, according to the ESHRE guideline. Obstetrical history and maternal age were noted at intake at the RPL clinic. The outcome of the first pregnancy after intake was documented. The performance of Brigham's model was evaluated through calibration and discrimination, in which the predicted pregnancy rates were compared to the observed pregnancy rates.Main results and the role of chance: The cohort included 739 women with a mean age of 33.1 years (±4.7 years) and with a median of three pregnancy losses at intake (range 2-10). The mean predicted pregnancy success rate was 9.8 percentage points higher in the Brigham model than the observed pregnancy success rate in the dataset (73.9% vs 64.0% (95% CI for the 9.8% difference 6.3-13.3%)). Calibration showed overestimation of the model and too extreme predictions, with a negative calibration intercept of -0.46 (95% CI -0.62 to -0.31) and a calibration slope of 0.42 (95% CI 0.11-0.73). The discriminative ability of the model was very low with a concordance statistic of 0.55 (95% CI 0.51-0.59). Recalibration of the Brigham model hardly improved the c-statistic (0.57; 95% CI 0.53-0.62).Limitations, reasons for caution: This is a retrospective study in which only the first pregnancy after intake was registered. There was no time frame as inclusion criterium, which is of importance in the counselling of couples with unexplained RPL. Only cases with a known pregnancy outcome were included.Wider implications of the findings: This is the first study externally validating the Brigham prognostic model that estimates the chance of a successful pregnancy in couples with unexplained RPL. The results show that the frequently used model overestimates the chances of a successful pregnancy, that predictions are too extreme on both the high and low ends and that they are not much more discriminative than random luck. There is a need for revising the prediction model to estimate the chance of a successful pregnancy in couples with unexplained RPL more accurately.Study funding/competing interest(s): No external funding was used and no competing interests were declared.Trial registration number: N/A.Keywords: external validation; miscarriage; prediction model; pregnancy success rate; recurrent pregnancy loss. Show less
BackgroundOnline magnetic resonance imaging (MRI)-guided radiotherapy of cervical cancer has the potential to further reduce dose to organs at risk (OAR) as compared to a library of plans (LOP)... Show moreBackgroundOnline magnetic resonance imaging (MRI)-guided radiotherapy of cervical cancer has the potential to further reduce dose to organs at risk (OAR) as compared to a library of plans (LOP) approach. This study presents a dosimetric comparison of an MRI-guided strategy with a LOP strategy taking intrafraction anatomical changes into account.MethodsThe 14 patients included in this study were treated with chemo radiation at our institute and received weekly MRIs after informed consent. The MRI-guided strategy consisted of treatment plans created on the weekly sagittal MRI with 3mm and 5mm planning target volume (PTV) margin for clinical target volume (CTV) cervix-uterus (MRI_3mm and MRI_5mm). The plans for the LOP strategy were based on interpolations of CTV cervix-uterus on pretreatment full and empty bladder scans. Dose volume histogram (DVH) parameters were compared for targets and OARs as delineated on the weekly transversal MRI, which was acquired on average 10min after the sagittal MRI.ResultsFor the MRI_5mm strategy D-98% of the high-risk CTV was at least 95% for all weekly MRIs of all patients, while for the LOP and MRI_3mm strategy this requirement was not satisfied for at least one weekly MRI for 1 and 3 patients, respectively. The average reduction of the volume of the reference dose (95% of the prescribed dose) as compared to the LOP strategy was 464cm(3) for the MRI_3mm strategy, and 422cm(3) for the MRI_5mm strategy. The bowel bag constraint V-40Gy<350cm(3) was violated for 13 patients for the LOP strategy and for 5 patients for both MRI_3mm and MRI_5mm strategy.ConclusionsWith online MRI-guided radiotherapy of cervical cancer considerable sparing of OARs can be achieved. If a new treatment plan can be generated and delivered within 10min, an online MRI-guided strategy with a 5mm PTV margin for CTV cervix-uterus is sufficient to account for intrafraction anatomical changes.Trial registrationNL44492.018.13. Show less
Background: While four-dimensional computed tomography (4DCT) is extensively used in adults, reluctance remains to use 4DCT in children. Day-to-day (interfractional) variability and irregular... Show moreBackground: While four-dimensional computed tomography (4DCT) is extensively used in adults, reluctance remains to use 4DCT in children. Day-to-day (interfractional) variability and irregular respiration (intrafractional variability) have shown to be limiting factors of 4DCT effectiveness in adults. In order to evaluate 4DCT applicability in children, the purpose of this study is to quantify inter- and intrafractional variability of respiratory motion in children and adults. The pooled analysis enables a solid comparison to reveal if 4DCT application for planning purposes in children could be valid.Methods/materials: We retrospectively included 90 patients (45 children and 45 adults), for whom the diaphragm was visible on abdominal/thoracic free-breathing cone beam CTs (480 pediatric, 524 adult CBCTs). For each CBCT, the cranial caudal position of end-exhale and end-inhale positions of the right diaphragm dome were manually selected in the projection images. The difference in position between both phases defines the amplitude. Cycle time equaled inspiratory plus expiratory time. We analyzed the variability of the inter- and intrafractional respiratory-induced diaphragm motion.Results: Ranges of respiratory motion characteristics were large in both children and adults (amplitude: 4-17 vs 5-24 mm, cycle time 2.1-3.9 vs 2.7-6.5 s). The mean amplitude was slightly smaller in children than in adults (10.7 vs 12.3 mm; P = 0.06). Interfractional amplitude variability was statistically significantly smaller in children than in adults (1.4 vs 2.2 mm; P = 0.00). Mean cycle time was statistically significantly shorter in children (2.9 vs 3.6 s; P = 0.00). Additionally, intrafractional cycle time variability was statistically significantly smaller in children (0.5 vs 0.7 s; P = 0.00).Conclusions: Overall variability is smaller in children than in adults, indicating that respiratory motion is more regular in children than in adults. This implies that a single pretreatment 4DCT could be a good representation of daily respiratory motion in children and will be at least equally beneficial for planning purposes as it is in adults. Show less
Background: In adults, a single pre-treatment four-dimensional CT (4D-CT) acquisition is often used to account for respiratory-induced target motion during radiotherapy. However, studies have... Show moreBackground: In adults, a single pre-treatment four-dimensional CT (4D-CT) acquisition is often used to account for respiratory-induced target motion during radiotherapy. However, studies have indicated that a 4D-CT is not always representative for respiratory motion. Our aim was to investigate whether respiratory-induced diaphragm motion in children on a single pre-treatment 4DCT can accurately predict respiratory-induced diaphragm motion as observed on cone beam CTs (CBCTs).Methods: Twelve patients (mean age 14.5 yrs.; range 8.6-17.9 yrs) were retrospectively included based on visibility of the diaphragm on abdominal or thoracic imaging data acquired during free breathing. A 4DCT for planning purposes and daily/weekly CBCTs (total 125; range 4-29 per patient) acquired prior to dose delivery were available. The amplitude, corresponding to the difference in position of the diaphragm in cranial-caudal direction in end-inspiration and end-expiration phases, was extracted from the 4DCT (A(4DCT)). The amplitude in CBCTs (A(CBCT)) was defined as displacement between averaged in- and expiration diaphragm positions on corresponding projection images, and the distribution of A(CBCT) was compared to A(4DCT) (one-sample t-test, significance level p<0.05).Results: Over all patients, the mean A(4DCT) was 10.4 mm and the mean A(CBCT) 11.6 mm. For 9/12 patients, A(4DCT) differed significantly (p<0.05) from A(CBCT). Differences >3 mm were found in 69/125 CBCTs (55%), with A(4DCT) mostly underestimating A(CBCT). For 7/12 patients, diaphragm positions differed significantly from the baseline position.Conclusion: Respiratory-induced diaphragm motion determined on 4DCT does not accurately predict the daily respiratory-induced diaphragm motion observed on CBCTs, as the amplitude and baseline position differed statistically significantly in the majority of patients. Regular monitoring of respiratory motion during the treatment course using CBCTs could yield a higher accuracy when a daily adaptation to the actual breathing amplitude takes place. Show less
Huijskens, S.C.; Dijk, I.W.E.M. van; Visser, J.; Balgobind, B.V.; Lindert, D. te; Rasch, C.R.N.; ... ; Bel, A. 2018
Background: Interfractional organ position variation might differ for abdominal organs and this could have consequences for defining safety margins. Therefore, the purpose of this study is to... Show moreBackground: Interfractional organ position variation might differ for abdominal organs and this could have consequences for defining safety margins. Therefore, the purpose of this study is to quantify interfractional position variations of abdominal organs in children in order to investigate possible correlations between abdominal organs and determine whether position variation is location-dependent.Methods: For 20 children (2.2-17.8 years), we retrospectively analyzed 113 CBCTs acquired during the treatment course, which were registered to the reference CT to assess interfractional position variation of the liver, spleen, kidneys, and both diaphragm domes. Organ position variation was assessed in three orthogonal directions and relative to the bony anatomy. Diaphragm dome position variation was assessed in the cranial-caudal (CC) direction only. We investigated possible correlations between position variations of the organs (Spearman's correlation test, p), and tested if organ position variations in the CC direction are related to the diaphragm dome position variations (linear regression analysis, R-2) (both tests: significance level p < 0.05). Differences of variations of systematic (Sigma) and random errors (sigma) between organs were tested (Bonferroni significance level p < 0.004).Results: In all directions, correlations between liver and spleen position variations, and between right and left kidney position variations were weak (p <= 0.43). In the CC direction, the position variations of the right and left diaphragm domes were significantly, and stronger, correlated with position variations of the liver (R-2 = 0.55) and spleen (R-2 = 0.63), respectively, compared to the right (R-2 = 0.00) and left kidney (R-2 = 0.25). Differences in Sigma and sigma between all organs were small and insignificant.Conclusions: No (strong) correlations between interfractional position variations of abdominal organs in children were observed. From present results, we concluded that diaphragm dome position variations could be more representative for superiorly located abdominal (liver, spleen) organ position variations than for inferiorly located (kidneys) organ position variations. Differences of systematic and random errors between abdominal organs were small, suggesting that for margin definitions, there was insufficient evidence of a dependence of organ position variation on anatomical location. Show less
Background and purpose: Radiotherapy involving the thoracic region is associated with cardiotoxicity in long-term childhood cancer survivors. We quantified heart volume changes during radiotherapy... Show moreBackground and purpose: Radiotherapy involving the thoracic region is associated with cardiotoxicity in long-term childhood cancer survivors. We quantified heart volume changes during radiotherapy in children (<18 years) and investigated correlations with patient and treatment related characteristics. Material and methods: Between 2010 and 2016, 34 children received radiotherapy involving the thoracic region. We delineated heart contours and measured heart volumes on 114 CBCTs. Relative volume changes were quantified with respect to the volume on the first CBCT (i.e., 100%). Cardiac radiation dose parameters expressed as 2 Gy/fraction equivalent doses were calculated from DVHs. Chemotherapy was categorized as treatment with anthracyclines, alkylating agents, vinca-alkaloids, and other. Results: The overall median heart volume reduction from the first to the last CBCT was 5.5% (interquartile range1.6-9.7%; p < 0.001). Heart volumes decreased significantly between the baseline measurement and the first week (Bonferroni's adjusted p = 0.002); volume changes were not significant during the following weeks. Univariate analysis showed a significant correlation between heart volume reduction and alkylating agents; however, no multivariate analyses could be done to further confirm this. Conclusions: We found a significant heart volume reduction in children during radiotherapy. Elucidation of underlying mechanisms, clinical relevance, and possible long-term consequences of early heart volume reduction require a prospective follow-up study. (C) 2018 Elsevier B.V. All rights reserved. Show less
Purpose: Deformable image registration (DIR) can be used to accumulate the absorbed dose distribution of daily image-guided adaptive external beam radiation treatment (EBRT) and brachytherapy (BT).... Show morePurpose: Deformable image registration (DIR) can be used to accumulate the absorbed dose distribution of daily image-guided adaptive external beam radiation treatment (EBRT) and brachytherapy (BT). Since dose-volume parameter addition assumes a uniform delivered EBRT dose around the planned BT boost, the added value of DIR over direct addition was investigated for dose accumulation in bladder and rectum.Material and methods: For 10 patients (EBRT 46/46.2 Gy(EQD2), EBRT + BT: D-90 85-90 Gy(EQD2), in equivalent dose in 2 Gy fractions), the actually delivered dose from adaptive volumetric-modulated arc therapy (VMAT)/intensity-modulated radiotherapy (IMRT) EBRT was calculated using the daily anatomy from the cone-beam computed tomography (CBCT) scans acquired prior to irradiation. The CBCT of the first EBRT fraction and the BT planning MRI were registered using DIR. The cumulative dose to the 2 cm(3) with the highest dose (D-2cm3) from EBRT and BT to the bladder and rectum was calculated and compared to direct addition assuming a uniform EBRT dose (UD).Results: Differences (DIR-UD) in the total EBRT + BT dose ranged between -0.2-3.9 Gy(EQD2) (bladder) and -1.0-3.7 Gy(EQD2) (rectum). The total EBRT + BT dose calculated with DIR was at most 104% of the dose calculated with the UD method.Conclusions: Differences between UD and DIR were small (< 3.9 Gy(EQD2)). The dose delivered with adaptive VMAT/IMRT EBRT to bladder and rectum near the planned BT boost can be considered uniform for the evaluation of bladder/rectum D-2cm3. Show less
