PURPOSE. Although fundus photography is extensively used in ophthalmology, refraction prevents accurate distance measurement on fundus images, as the resulting scaling differs between subjects due... Show morePURPOSE. Although fundus photography is extensively used in ophthalmology, refraction prevents accurate distance measurement on fundus images, as the resulting scaling differs between subjects due to varying ocular anatomy. We propose a PARaxial Optical fundus Scaling (PAROS) method to correct for this variation using commonly available clinical data. METHODS. The complete optics of the eye and fundus camera were modeled using ray transfer matrix formalism to obtain fundus image magnification. The subject’s ocular geometry was personalized using biometry, spherical equivalent of refraction (RSE), keratometry, and/or corneal topography data. The PAROS method was validated using 41 different eye phantoms and subsequently evaluated in 44 healthy phakic subjects (of whom 11 had phakic intraocular lenses [pIOLs]), 29 pseudophakic subjects, and 21 patients with uveal melanoma. RESULTS. Validation of the PAROS method showed small differences between model and actual image magnification (maximum 3.3%). Relative to the average eye, large differences in fundus magnification were observed, ranging from 0.79 to 1.48. Magnification was strongly inversely related to RSE (R2 = 0.67). In phakic subjects, magnification was directly proportional to axial length (R2 = 0.34). The inverse relation was seen in pIOL (R2 = 0.79) and pseudophakic (R2 = 0.12) subjects. RSE was a strong contributor to magnification differences (1%–83%). As this effect is not considered in the commonly used Bennett–Littmann method, statistically significant differences up to 40% (mean absolute 9%) were observed compared to the PAROS method (P < 0.001). CONCLUSIONS. The significant differences in fundus image scaling observed among subjects can be accurately accounted for with the PAROS method, enabling more accurate quantitative assessment of fundus photography Show less
Background: Uveal melanoma (UM) is a rare intraocular tumor with a dismal prognosis once metastasized. This study provides a nationwide overview and time trends of patients diagnosed with primary... Show moreBackground: Uveal melanoma (UM) is a rare intraocular tumor with a dismal prognosis once metastasized. This study provides a nationwide overview and time trends of patients diagnosed with primary UM in the Netherlands between 1989 and 2019. Methods: A retrospective population-based cohort study based on patients with primary UM from the database of the Netherlands Cancer Registry (NCR), linked with the national population registry Statistics Netherlands on inhabitants' cause of death. Two time periods (1989-2004, 2005-2019) were compared with descriptive statistics. Kaplan-Meier and (multivariate) Cox proportional hazard models were used to assess changes over time for overall survival (OS) and cancer-specific survival (CSS). Results: In total, 5036 patients were analyzed with a median age of 64.0 years at the time of diagnosis. The number of patients increased over time. In the first (1989-2004) and second (2005-2019) period, 32% versus 54% of the patients received radiotherapy (p < 0.001). The median FU time was 13.4 years. The median OS of the first and second periods was 9.5 (95% CI 8.7-10.3) versus 11.3 years (95% CI 10.3-12.3; p < 0.001). The median CSS was 30.0 years (95% CI NA) in the first period and not reached in the second period (p = 0.008). In multivariate analysis (MVA), female gender (HR 0.85; 95% CI 0.79-0.92, p < 0.001) and radiotherapy treatment (HR 0.73; 95% CI 0.64-0.83, p < 0.001) were associated with better OS. Radiotherapy treatment (HR 0.74; 95% CI 0.61-0.90, p = 0.002) was also associated with better CSS. The period of diagnosis was not associated with OS or CSS. Conclusions: In this study of patients with primary UM, there was a shift to the diagnosis of smaller tumors, possibly due to stage migration. There was also an increase in eye-preserving treatments over time. OS and CSS were modestly improved in the second time period; however, the time period was not associated with OS or CSS in multivariate analyses. Show less
Ree, M.H. van der; Cuculich, P.S.; Herk, M. van; Hugo, G.D.; Balt, J.C.; Bates, M.; ... ; Postema, P.G. 2023
BackgroundStereotactic arrhythmia radioablation (STAR) is a potential new therapy for patients with refractory ventricular tachycardia (VT). The arrhythmogenic substrate (target) is synthesized... Show moreBackgroundStereotactic arrhythmia radioablation (STAR) is a potential new therapy for patients with refractory ventricular tachycardia (VT). The arrhythmogenic substrate (target) is synthesized from clinical and electro-anatomical information. This study was designed to evaluate the baseline interobserver variability in target delineation for STAR.MethodsDelineation software designed for research purposes was used. The study was split into three phases. Firstly, electrophysiologists delineated a well-defined structure in three patients (spinal canal). Secondly, observers delineated the VT-target in three patients based on case descriptions. To evaluate baseline performance, a basic workflow approach was used, no advanced techniques were allowed. Thirdly, observers delineated three predefined segments from the 17-segment model. Interobserver variability was evaluated by assessing volumes, variation in distance to the median volume expressed by the root-mean-square of the standard deviation (RMS-SD) over the target volume, and the Dice-coefficient.ResultsTen electrophysiologists completed the study. For the first phase interobserver variability was low as indicated by low variation in distance to the median volume (RMS-SD range: 0.02-0.02 cm) and high Dice-coefficients (mean: 0.97 +/- 0.01). In the second phase distance to the median volume was large (RMS-SD range: 0.52-1.02 cm) and the Dice-coefficients low (mean: 0.40 +/- 0.15). In the third phase, similar results were observed (RMS-SD range: 0.51-1.55 cm, Dice-coefficient mean: 0.31 +/- 0.21).ConclusionsInterobserver variability is high for manual delineation of the VT-target and ventricular segments. This evaluation of the baseline observer variation shows that there is a need for methods and tools to improve variability and allows for future comparison of interventions aiming to reduce observer variation, for STAR but possibly also for catheter ablation. Show less
PurposeMRI is increasingly used in the diagnosis and therapy planning of uveal melanoma (UM). In this prospective cohort study, we assessed the radiological characteristics, in terms of anatomical... Show morePurposeMRI is increasingly used in the diagnosis and therapy planning of uveal melanoma (UM). In this prospective cohort study, we assessed the radiological characteristics, in terms of anatomical and functional imaging, of UM after ruthenium-106 plaque brachytherapy or proton beam therapy (PBT) and compared them to conventional ultrasound.MethodsTwenty-six UM patients were evaluated before and 3, 6 and 12 months after brachytherapy (n = 13) or PBT (n = 13). Tumour prominences were compared between ultrasound and MRI. On diffusion-weighted imaging, the apparent diffusion value (ADC), and on perfusion-weighted imaging (PWI), the time-intensity curves (TIC), relative peak intensity and outflow percentages were determined. Values were compared between treatments and with baseline.ResultsPre-treatment prominences were comparable between MRI and ultrasound (mean absolute difference 0.51 mm, p = 0.46), but larger differences were observed post-treatment (e.g. 3 months: 0.9 mm (p = 0.02)). Pre-treatment PWI metrics were comparable between treatment groups. After treatment, brachytherapy patients showed favourable changes on PWI (e.g. 67% outflow reduction at 3 months, p < 0.01). After PBT, significant perfusion changes were observed at a later timepoint (e.g. 38% outflow reduction at 6 months, p = 0.01). No consistent ADC changes were observed after either treatment, e.g. a 0.11 x 10(-3)mm(2)/s increase 12 months after treatment (p = 0.15).ConclusionMR-based follow-up is valuable for PBT-treated patients as favourable perfusion changes, including a reduction in outflow, can be detected before a reduction in size is apparent on ultrasound. For brachytherapy, a follow-up MRI is of less value as already 3 months post-treatment a significant size reduction can be measured on ultrasound. Show less
Retinopathy and optic neuropathy are well-known, severe ocular complications in patients undergoing radiation therapy for brain, head, and neck cancer. However, little is known about the prevalence... Show moreRetinopathy and optic neuropathy are well-known, severe ocular complications in patients undergoing radiation therapy for brain, head, and neck cancer. However, little is known about the prevalence and dose-response relationship of retinopathy and optic neuropathy in these patients. More knowledge about the prevalence and dose-response relationship may contribute to developing a high-precision radiation therapy approach.Background: Patients with brain, head, and neck tumors experience a decline in their quality of life due to radiation retinopathy and optic neuropathy. Little is known about the dose-response relationship and patient characteristics. We aimed to systematically review the prevalence of radiation retinopathy and optic neuropathy. Method: The primary outcome was the pooled prevalence of radiation retinopathy and optic neuropathy. The secondary outcome included the effect of the total radiation dose prescribed for the tumor according to the patient's characteristics. Furthermore, we aimed to evaluate the radiation dose parameters for organs at risk of radiation retinopathy and optic neuropathy. Results: The pooled prevalence was 3.8%. No retinopathy was reported for the tumor's prescribed dose of 50 Gy than <50 Gy. We observed a higher prevalence rate for retinopathy (6.0%) than optic neuropathy (2.0%). Insufficient data on the dose for organs at risk were reported. Conclusion: The prevalence of radiation retinopathy was higher compared to optic neuropathy. This review emphasizes the need for future studies considering retinopathy and optic neuropathy as primary objective parameters. Show less
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
Jaarsma-Coes, M.G.; Ferreira, T.A.; Marinkovic, M.; Vu, T.H.K.; Vught, L. van; Haren, G.R.V.; ... ; Beenakker, J.W.M. 2023
Objective: Conventionally, ocular proton therapy (PT) is planned using measurements obtained by an ophthalmologist using ultrasound, fundoscopy, biometry, and intraoperative assessments. Owing to... Show moreObjective: Conventionally, ocular proton therapy (PT) is planned using measurements obtained by an ophthalmologist using ultrasound, fundoscopy, biometry, and intraoperative assessments. Owing to the recent advances in magnetic resonance imaging (MRI) of uveal melanoma (UM), it is possible to acquire high-resolution 3-dimensional images of the eye, providing the opportunity to incorporate MRI in ocular PT planning. In this study, we described how these measurements can be obtained using MRI, compared the MRI-based measurements with conventional ophthalmic measurements, and identified potential pitfalls for both modalities. Design: Cross-sectional study. Subjects: Data from 23 consecutive patients with UM treated with PT were retrospectively evaluated. Methods: Magnetic resonance imaging-based measurements of axial length, tumor height and basal diameter, and marker-tumor distances were compared with the conventional ophthalmic measurements, and discrepancies were evaluated in a multidisciplinary setting. Main Outcome Measures: Tumor prominence and basal diameters on MRI and ultrasound, axial length on MRI and biometry, tumor-marker distances on MRI and measured intraoperatively. Results: The mean absolute differences of the tumor height and basal diameter measurements between ultrasound and MRI were 0.57 mm and 1.44 mm, respectively. Larger absolute differences in height and basal diameter were observed when the full tumor extent was not visible on ultrasound (0.92 mm and 1.67 mm, respectively) compared with when the full tumor extent was visible (0.44 mm and 1.15 mm, respectively). When the full tumor was not visible on ultrasound, MRI was considered more reliable. Tumor-marker distances measured using MRI and intraoperative techniques differed < 1 mm in 55% of the markers. For anteriorly located and mushroom-shaped tumors (25% of the markers), MRI provided more accurate measurements. In flat UM (15% of the markers), however, it was difficult to delineate the tumor on MRI. The mean absolute difference in axial length between optical biometry and MRI was 0.50 mm. The presence of the tumor was found to influence optical biometry in 15 of 22 patients; the remaining patients showed a better agreement (0.30 mm). Magnetic resonance imaging-based biometry was considered more reliable in patients with UM. Conclusions: Magnetic resonance imaging allowed for the 3-dimensional assessment of the tumor and surrounding tissue. In specific patients, it provided a more reliable measurement of axial length, tumor dimensions, and marker-tumor distances and could contribute to a more accurate treatment planning. Never-theless, a combined evaluation remains advised, especially for flat UM. Show less
Background and Purpose: Three-dimensional (3D) Magnetic Resonance Imaging (MRI) is increasingly used to complement conventional two-dimensional ultrasound in the assessment of tumour dimension... Show moreBackground and Purpose: Three-dimensional (3D) Magnetic Resonance Imaging (MRI) is increasingly used to complement conventional two-dimensional ultrasound in the assessment of tumour dimension measurement of uveal melanoma. However, the lack of definitions of the 3D measurements of these tumour dimensions hinders further adaptation of MRI in ocular radiotherapy planning. In this study, we composed 3D MR-based definitions of tumour prominence and basal diameter and compared them to conventional ultrasound. Materials and methods: Tumours were delineated on 3DT2 and contrast-enhanced 3DT1 (T1gd) MRI for 25 pa-tients. 3D definitions of tumour prominence and diameter were composed and evaluated automatically on the T1gd and T2 contours. Automatic T1gd measurements were compared to manual MRI measurements, to auto-matic T2 measurements and to manual ultrasound measurements. Results: Prominence measurements were similar for all modalities (median absolute difference 0.3 mm). Auto-matic T1gd diameter measurements were generally larger than manual MRI, automatic T2 and manual ultra-sound measurements (median absolute differences of 0.5, 1.6 and 1.1 mm respectively), mainly due to difficulty defining the axis of the largest diameter. Largest differences between ultrasound and MRI for both prominence and diameter were found in anteriorly located tumours (up to 1.6 and 4.5 mm respectively), for which the tumour extent could not entirely be visualized with ultrasound. Conclusions: The proposed 3D definitions for tumour prominence and diameter agreed well with ultrasound measurements for tumours for which the extent was visible on ultrasound. 3D MRI measurements generally provided larger diameter measurements than ultrasound. In anteriorly located tumours, the MRI measurements were considered more accurate than conventional ultrasound. Show less
Simple Summary Radiotherapy is widely used as treatment for localized prostate cancer. Due to a high incidence and a good survival after treatment, a large number of prostate cancer survivors are... Show moreSimple Summary Radiotherapy is widely used as treatment for localized prostate cancer. Due to a high incidence and a good survival after treatment, a large number of prostate cancer survivors are at risk of developing late radiation toxicity. Symptoms may significantly affect quality of life; therefore, the monitoring of toxicities and evaluating their impact are increasingly important matters. Toxicities have always been assessed by physicians, but there is a growing interest in the use of questionnaires to be completed by patients themselves, so-called patient-reported outcome measures. The aim of this study was to compare both outcomes in long-term prostate cancer survivors, and to determine which outcome correlates best with a biological predictor of late radiation toxicity. In symptomatic patients, we found a low agreement; patients assigned greater severity to symptoms than the trial physician assistant did. Neither outcome correlated with the biological predictor. Consideration of both perspectives seems warranted to provide the best care. Patient-reported outcome measures (PROMs) are advocated for the monitoring of toxicity after radiotherapy. However, studies comparing physician- and patient-reported toxicity show low concordance. In this study, we compared physician- and patient-reported toxicity in long-term prostate cancer survivors after radiotherapy, and we determined the correlation with a presumable risk factor for late toxicity: gamma-H2AX foci decay ratio (FDR). Patients formerly included in a prospective study were invited to participate in this new study, comprising one questionnaire and one call with a trial physician assistant. Concordance was calculated for seven symptoms. Gamma-H2AX FDRs were determined in ex vivo irradiated lymphocytes in a previous analysis. Associations between FDR and long-term prevalence of toxicity were assessed using univariable logistic regression analyses. The 101 participants had a median follow-up period of 9 years. Outcomes were discordant in 71% of symptomatic patients; in 21%, the physician-assessed toxicity (using CTCAE) was higher, and, in 50%, the patients reported higher toxicity. We did not find a correlation between presence of toxicity at long-term follow-up and FDR. In conclusion, patients assigned greater severity to symptoms than the trial physician assistant did. Consideration of both perspectives may be warranted to provide the best care. Show less
Bakker, A.; Valverde, C.P.T.; Tienhoven, G. van; Kolff, M.W.; Kok, H.P.; Slotman, B.J.; ... ; Crezee, H. 2022
Purpose: To investigate the impact of hyperthermia thermal dose (TD) on locoregional control (LRC), overall survival (OS) and toxicity in locoregional recurrent breast cancer patients treated with... Show morePurpose: To investigate the impact of hyperthermia thermal dose (TD) on locoregional control (LRC), overall survival (OS) and toxicity in locoregional recurrent breast cancer patients treated with postoperative re-irradiation and hyperthermia.Methods: In this retrospective study, 112 women with resected locoregional recurrent breast cancer treated in 2010-2017 with postoperative re-irradiation 8frx4Gy (n = 34) or 23frx2Gy (n = 78), combined with 4-5 weekly hyperthermia sessions guided by invasive thermometry, were subdivided into 'low' (n = 56) and 'high' TD (n = 56) groups by the best session with highest median cumulative equivalent minutes at 43 degrees C (Best CEM43T50) < 7.2 min and >7.2 min, respectively. Actuarial LRC, OS and late toxicity incidence were analyzed. Backward multivariable Cox regression and inverse probability weighting (IPW) analysis were performed.Results: TD subgroups showed no significant differences in patient/treatment characteristics. Median follow-up was 43 months (range 1-107 months). High vs. low TD was associated with LRC (p = 0.0013), but not with OS (p = 0.29) or late toxicity (p = 0.58). Three-year LRC was 74.0% vs. 92.3% in the low and high TD group, respectively (p = 0.008). After three years, 25.0% and 0.9% of the patients had late toxicity grade 3 and 4, respectively. Multivariable analysis showed that distant metastasis (HR 17.6; 95%CI 5.2-60.2), lymph node involvement (HR 2.9; 95%CI 1.2-7.2), recurrence site (chest wall vs. breast; HR 4.6; 95%CI 1.8-11.6) and TD (low vs. high; HR 4.1; 95%CI 1.4-11.5) were associated with LRC. TD was associated with LRC in IPW analysis (p = 0.0018).Conclusions: High thermal dose (best CEM43T50 >= 7.2 min) was associated with significantly higher LRC for patients with locoregional recurrent breast cancer treated with postoperative re-irradiation and hyperthermia, without augmenting toxicity. (C) 2021 The Authors. Published by Elsevier B.V. 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
Marinkovic, M.; Pors, L.J.; Berg, V. van den; Peters, F.P.; Schalenbourg, A.; Zografos, L.; ... ; Horeweg, N. 2021
Simple Summary This study aims to assess cancer control and preservation of the eye and visual acuity after proton therapy abroad for eye melanoma. For this, medical files were reviewed of Dutch... Show moreSimple Summary This study aims to assess cancer control and preservation of the eye and visual acuity after proton therapy abroad for eye melanoma. For this, medical files were reviewed of Dutch uveal melanoma patients who were treated in Switzerland with proton therapy from 1987 to 2019. The tumours of these patients were too large and/or localised too close to the optic nerve to be treated with local plaque irradiation. There were 103 patients, of whom one had a uveal melanoma in both eyes. The tumours were relatively large and often localised around the central part of the retina. At five years after treatment, proton therapy had controlled the uveal melanomas of 94% of the patients and 81% had preserved their eye. Spread of the cancer beyond the eye was observed in 30% of the patients. Most patients (79%) became blind or had severe visual impairment after proton therapy; a small group of patients had mild or no visual impairment (17%). The size of the tumour, its localisation and the dose of proton therapy were important for the risk of decline in visual acuity. This study shows that proton therapy abroad for uveal melanoma is feasible and yields good results. Objective: To assess oncological and ophthalmological outcomes after international referral of uveal melanoma patients for proton therapy. Materials and Methods: This is a retrospective study among Dutch uveal melanoma patients who were treated in Switzerland with 60.0 CGE proton therapy (in 4 fractions) from 1987 to 2019. All patients were ineligible for brachytherapy due to tumour size and/or proximity to the optic nerve. Time-to-event analyses were performed using Kaplan-Meier's methodology and Cox proportional hazards models. Results: There were 103 patients (104 eyes) with a median largest tumour diameter of 19 mm (range 6-26 mm). Tumours were localised centrally (11%), mid-peripherally (65%) or peripherally (34%). Median follow-up was 7 years. Five-year local control, distant metastasis-free survival and eye preservation rates were 94%, 70% and 81% respectively. At five years, severe, moderate and mild visual impairment was observed in respectively 79%, 4% and 6% of the patients. Larger tumour volumes and more central tumour localisation were associated with severe visual impairment. After correction for these factors, dose to the macula, optic disc and retina, but not optic nerve was significantly associated with severe visual impairment. Conclusion: International referral for proton therapy yielded good tumour control and eye preservation rates, but risk of distant metastasis and severe visual impairment were substantial, possibly due to the selection of advanced tumour stages and/or central localisation. Dose to the macula may be more relevant than dose to the optic nerve for preservation of visual acuity, which is relevant for the treatment planning of proton therapy. Show less
Virgolin, M.; Wang, Z.; Balgobind, B.V.; Dijk, I.W.E.M. van; Wiersma, J.; Kroon, P.S.; ... ; Alderliesten, T. 2020
To study radiotherapy-related adverse effects, detailed dose information (3D distribution) is needed for accurate dose-effect modeling. For childhood cancer survivors who underwent radiotherapy in... Show moreTo study radiotherapy-related adverse effects, detailed dose information (3D distribution) is needed for accurate dose-effect modeling. For childhood cancer survivors who underwent radiotherapy in the pre-CT era, only 2D radiographs were acquired, thus 3D dose distributions must be reconstructed from limited information. State-of-the-art methods achieve this by using 3D surrogate anatomies. These can however lack personalization and lead to coarse reconstructions. We present and validate a surrogate-free dose reconstruction method based on Machine Learning (ML). Abdominal planning CTs (n = 142) of recently-treated childhood cancer patients were gathered, their organs at risk were segmented, and 300 artificial Wilms' tumor plans were sampled automatically. Each artificial plan was automatically emulated on the 142 CTs, resulting in 42,600 3D dose distributions from which dose-volume metrics were derived. Anatomical features were extracted from digitally reconstructed radiographs simulated from the CTs to resemble historical radiographs. Further, patient and radiotherapy plan features typically available from historical treatment records were collected. An evolutionary ML algorithm was then used to link features to dose-volume metrics. Besides 5-fold cross validation, a further evaluation was done on an independent dataset of five CTs each associated with two clinical plans. Cross-validation resulted in mean absolute errors <= 0.6 Gy for organs completely inside or outside the field. For organs positioned at the edge of the field, mean absolute errors <= 1.7 Gy for D-mean, <= 2.9 Gy for D-2cc, and <= 13% for V-5 Gy and V-10 Gy, were obtained, without systematic bias. Similar results were found for the independent dataset. To conclude, we proposed a novel organ dose reconstruction method that uses ML models to predict dose-volume metric values given patient and plan features. Our approach is not only accurate, but also efficient, as the setup of a surrogate is no longer needed. Show less
Proton beam therapy (PBT) for uveal melanoma (UM) is performed in sitting position, while the acquisition of the Magnetic resonance (MR)-images for treatment planning is performed in supine... Show moreProton beam therapy (PBT) for uveal melanoma (UM) is performed in sitting position, while the acquisition of the Magnetic resonance (MR)-images for treatment planning is performed in supine position. We assessed the effect of this difference in position on the eye- and tumour- shape. Seven subjects and six UM-patients were scanned in supine and a seating mimicking position. The distances between the tumour/sclera in both positions were calculated. The median distance between both positions was 0.1 mm. Change in gravity direction produced no substantial changes in sclera and tumour shape, indicating that supinely acquired MR-images can be used to plan ocular-PBT. Show less
Bakker, A.; Zweije, R.; Tienhoven, G. van; Kok, H.P.; Sijbrands, J.; Bongard, H.J.G.D. van den; ... ; Crezee, H. 2020
Temperature measurement during superficial hyperthermia is limited by poor spatial resolution. We investigated two sheets to improve temperature monitoring of the skin surface. Two different sheets... Show moreTemperature measurement during superficial hyperthermia is limited by poor spatial resolution. We investigated two sheets to improve temperature monitoring of the skin surface. Two different sheets were studied with a grid of temperature sensors with one sensor per similar to 5 cm(2). The first was a matrix of multisensor thermocouple probes laced through a silicone sheet. The second sheet had rows of thermistors connected by meandering copper leads mounted on stretchable printed circuit board (SPCB). Accuracy, temperature resolution and two hour stability of both sheets were investigated. Furthermore, we determined the ability to follow body contours, thermal conduction errors and electromagnetic (EM) compatibility to clinically used 434 and 915 MHz hyperthermia applicators. For both sheets the accuracy (<= 0.2 degrees C), temperature resolution (<= 0.03 degrees C) and stability (<= 0.01 degrees C hr(-1)) were adequate for clinical use. Thermal conduction errors ranged from 5.25-11.25 mm vs. 2.15 mm for the thermocouple probe and thermistor, respectively. Both sheets could follow body contours, where the ratio air/water bolus surface was <5%. When aligned perpendicularly to the EM field the meandering copper tracks used on the SPCB did induce self-heating, while the thermocouple probes did not. Self-heating had a linear relationship with the angle of the leads with respect to the EM field direction for both sensors at both frequencies. Self-heating of the thermistor was similar for both frequencies, while it was circa two-fold higher for 915 vs. 434 MHz for the thermocouple. The use of SPCB technology for skin surface monitoring was promising. However, suppressing self-heating induced by the horseshoe shaped copper tracks needed for stretchability of the SPCB requires more in-depth investigation. The thermocouple matrix was the most promising for clinical application, meeting 6/7 of the major requirements for skin surface temperature monitoring when positioned perpendicular to the EM field. Show less
Objective: To perform a nationwide population based study in ATC on incidence, treatment and survival.Design: Retrospective cohort study.Methods: All patients with primary ATC between 1989 and 2016... Show moreObjective: To perform a nationwide population based study in ATC on incidence, treatment and survival.Design: Retrospective cohort study.Methods: All patients with primary ATC between 1989 and 2016 were identified in the Netherlands Cancer Registry (NCR). Of all these patients excerpts from the pathology reports from PALGA: Dutch Pathology registry were linked to the data of the NCR. Standardized incidences were calculated, survival was estimated using Kaplan-Meier method and univariable statistically significant factors were included in a multivariable regression model.Results: In total, 812 patients were included. Mean standardized incidence rates were 0.18/100 000 (range 0.11-0.27/100 000) with a significant trend over the years with an estimated annual percentage change of 1.3% per year (95% CI 0.4-2.1%). Median overall survival was 2.2 months, and estimated 1-year survival was 12%. Patients without distant metastases at diagnosis had an estimated 1-year survival of 21.6%. Prognostic factors for prolonged survival were double or triple therapy, age below 65 years, M0-status and absence of bilateral lymph node metastases.Conclusions: ATC is rare, but often lethal, form of thyroid cancer, with a median survival of 2 months and 1-year survival of approximately 10%. The incidence is slightly rising in the Netherlands over the past 3 decades. There appears to be a subgroup of patients that survive longer, mainly those with relatively limited disease who underwent double or triple therapy. Further research is needed to define these patients more distinctively. Show less
Walraven, J.E.W.; Desar, I.M.E.; Hoeven, J.J.M. van der; Aben, K.K.H.; Hillegersberg, R. van; Rasch, C.R.N.; ... ; Verhoeven, R.H.A. 2019
Introduction: For optimal oncological care, it is recommended to discuss every patient with cancer in a multidisciplinary team meeting (MDTM). This is a time consuming and expensive practice,... Show moreIntroduction: For optimal oncological care, it is recommended to discuss every patient with cancer in a multidisciplinary team meeting (MDTM). This is a time consuming and expensive practice, leading to a growing demand to change the current workflow. We aimed to investigate the number of patients discussed in MDTMs and to identify characteristics associated with not being discussed.Methods: Data of patients with a newly diagnosed solid malignant tumour in 2015 and 2016 were analysed through the nationwide population-based Netherlands Cancer Registry (NCR). We clustered tumour types in groups that were frequently discussed within a tumour-specific MDTM. Tumour types without information about MDTMs in the NCR were excluded. Multivariable logistic regression analyses were used to analyse factors associated with not being discussed.Results: Out of 105.305 patients with cancer, 91% were discussed in a MDTM, varying from 74% to 99% between the different tumour groups. Significantly less frequently discussed were patients aged >= 75 years (odds ratio [OR] = 0.7, 95% confidence interval [CI] = 0.6-0.7), patients diagnosed with disease stage I (OR = 0.5, 95% CI = 0.5-0.6), IV (OR = 0.4, 95% CI = 0.4-0.4) or unknown (OR = 0.2, 95% CI = 0.2-0.2) and patients who received no treatment (OR=0.3, 95% CI=0.3-0.3). Patients who received a multidisciplinary treatment were more likely to be discussed in contrary to a monodisciplinary treatment (OR = 4.6, 95% CI = 4.2-5.1).Conclusion: In general, most patients with cancer were actually discussed in a MDTM, although differences were observed between tumour groups. Factors associated with not being discussed may, at least partially, reflect the absence of a multidisciplinary question. These results form a starting point for debate on a more durable and efficient new MDTM strategy. (C) 2019 Elsevier Ltd. All rights reserved. Show less
Purpose: To determine the accuracy of MRI in detecting craniocaudal tumour extension, compared to histopathology, of the hysterectomy specimen in patients with early-stage uterine cervical cancer.... Show morePurpose: To determine the accuracy of MRI in detecting craniocaudal tumour extension, compared to histopathology, of the hysterectomy specimen in patients with early-stage uterine cervical cancer. Three complementary methods were investigated.Materials and methods: Thirty-four patients with early-stage cervical cancer had pre-operative MRI, followed by radical hysterectomy or trachelectomy. 1) craniocaudal tumour extension was measured on MRI by two radiologists and compared to microscopy by a pathologist, 2) to compensate for changes in uterine shape between pre-operative MRI and the surgical specimen, craniocaudal tumour extensions were directly compared and appreciated as being a part of a 3-dimensional tumour by a radiation oncologist and resident, and 3) tumour size on MRI was compared macroscopically after digital non-rigid registration of the uterus, uterine cavity and tumour of both modalities.Results: The craniocaudal tumour extension measured on histopathology minus MRI gives: 1) on average +3 mm difference when measured by a radiologist compared to the microscopic extension (range -13 to +15 mm), 2) -0.2 mm (range -11 to +6.0 mm) when evaluated on MRI by a radiation oncologist compared to the macroscopic tumour; 3) after non-rigid organ registration, a margin of 10 mm around the tumour on MRI would be needed to cover 95% of the tumour in 90% of the patients.Conclusions: Results indicate that microscopic tumour extension towards the uterine fundus is within a margin of 10 mm around the visible tumour on MRI. The major source of measurement uncertainty is post-surgical change of organ shape and form. (C) 2019 The Author(s). Published by Elsevier B.V. on behalf of European Society for Radiotherapy and Oncology. Show less
Heukelom, J.; Navran, A.; Gouw, Z.A.R.; Tesselaar, M.E.; Zuur, C.L.; Werkhoven, E. van; ... ; Al-Mamgani, A. 2019
Objective The aim of the current study was to determine the incidence of organ function preservation failure (OFPF) in patients with head and neck squamous cell carcinoma (HNSCC) treated by (chemo... Show moreObjective The aim of the current study was to determine the incidence of organ function preservation failure (OFPF) in patients with head and neck squamous cell carcinoma (HNSCC) treated by (chemo)radiotherapy and to identify its risk factors. Study Design Retrospective cohort analysis. Setting Tertiary cancer care center. Subjects and Methods A single-center retrospective cohort analysis was done (n = 703) in which OFPF after (chemo)radiotherapy was assessed. OFPF was defined as local failure or pure functional failure in the absence of local failure because of major surgical intervention (total laryngectomy, commando resection, permanent tracheostomy) or feeding tube dependence >2 years. Results OFPF occurred in 153 patients (21.8%). Reasons for OFPF were local failure in 103 patients (14.6%) and functional failure in 50 patients (7.2%). Evidence of functional failure included need for total laryngectomy (n = 9, 1.3%), commando resection (n = 2, 0.3%), permanent tracheostomy (n = 16, 2.3%), and/or long-term feeding tube for functional reasons (n = 23, 3.3%). In a Cox proportional hazards model, OFPF was worse for patients with T4 tumors (hazard ratio [HR] <0.5 and P < .001 for all other stages), for laryngeal vs oropharyngeal cancer (HR, 1.83; 95% confidence interval [CI], 1.20-2.79, P = .005, hypopharyngeal not significant), and for smokers (HR, 1.68; 95% CI, 1.10-2.56, P = .015). Exploratory multivariate analysis by tumor site showed that T4 tumor and pretreatment tracheostomy were the strongest predictive factors for OFPF in laryngeal and hypopharyngeal carcinoma while T4 tumor and smoking were predictive for poor OFPF in oropharyngeal carcinoma. Conclusion This work shows a detrimental effect of smoking on functional outcomes after (chemo-)radiotherapy for HNSCC. Moreover, T4 tumor, laryngeal subsite, and pretreatment tracheostomy are strong predictors of OFPF. Show less
Visser, J.; Boer, P. de; Crama, K.F.; Kesteren, Z. van; Rasch, C.R.N.; Stalpers, L.J.A.; Bel, A. 2019
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
