Use of image-guided radiation therapy (IGRT) helps to account for daily prostate position changes during radiation therapy for prostate cancer. However, guidelines for the use of IGRT are scarce.An... Show moreUse of image-guided radiation therapy (IGRT) helps to account for daily prostate position changes during radiation therapy for prostate cancer. However, guidelines for the use of IGRT are scarce.An ESTRO panel consisting of leading radiation oncologists and medical physicists was assembled to review the literature and formulate a consensus guideline of methods and procedure for IGRT in prostate cases. Advanced methods and procedures are also described which the committee judged relevant to further improve clinical practice. Moreover, ranges for margins for the three most popular IGRT scenarios have been suggested as examples. (C) 2019 Elsevier B.V. All rights reserved. Show less
Ende, R.P.J. van den; Rigter, L.S.; Kerkhof, E.M.; Meerten, E.L.V. van; Rijkmans, E.C.; Lambregts, D.M.J.; ... ; Heide, U.A. van der 2019
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: To analyse the variability of respiratory motion during image-guided radiotherapy in paediatric cancer patients and to investigate possible relationships thereof with... Show moreBackground and purpose: To analyse the variability of respiratory motion during image-guided radiotherapy in paediatric cancer patients and to investigate possible relationships thereof with patient-specific factors.Material and methods: Respiratory-induced diaphragm motion was retrospectively analysed on 480 cone beam CTs acquired during the treatment course of 45 children (<18 years). The cranial-caudal positions of the top of the right diaphragm in exhale and inhale phases were manually selected in the projection images. The difference in position between both phases defines the amplitude. The cycle time equalled inspiratory plus expiratory time. We analysed the variability of the intra- and interfractional respiratory motion and studied possible correlations between respiratory-induced diaphragm motion and age, height, and weight.Results: Over all patients, mean amplitude and cycle time were 10.7 mm (range 4.1-17.4 mm) and 2.9 s (range 2.1-3.9 s). Intrafractional variability was larger than interfractional variability (2.4 mm vs. 1.4 mm and 0.5 s vs. 0.4 s for amplitude and cycle time, respectively). Correlations between mean amplitude and patient-specific factors were significant but weak (p < 0.05, p <= 0.45).Conclusions: Large ranges of amplitude and cycle time and weak correlations confirm that respiratory motion is patient-specific and requires an individualized approach to account for. Since interfractional variability was small, we suggest that a pre-treatment 4DCT in children could be sufficiently predictive to quantify the respiratory motion. (C) 2017 Elsevier B.V. All rights reserved. Show less
Huijskens, S.C.; Dijk, I.W.E.M. van; Jong, R. de; Visser, J.; Fajardo, R.D.; Ronckers, C.M.; ... ; Bel, A. 2015
Background and purpose: To quantify renal and diaphragmatic interfractional motion in order to estimate systematic and random errors, and to investigate the correlation between interfractional... Show moreBackground and purpose: To quantify renal and diaphragmatic interfractional motion in order to estimate systematic and random errors, and to investigate the correlation between interfractional motion and patient-specific factors.Material and methods: We used 527 retrospective abdominal-thoracic cone beam CT scans of 39 childhood cancer patients (<18 years) to quantify renal motion relative to bony anatomy in the left-right (LR), cranio-caudal (CC) and anterior-posterior (AP) directions, and diaphragmatic motion in the CC direction only. Interfractional motion was quantified by distributions of systematic and random errors in each direction (standard deviations Sigma and sigma, respectively). Also, correlation between organ motion and height was analyzed.Results: Inter-patient organ motion varied widely, with the largest movements in the CC direction. Values of Sigma in LR, CC, and AP directions were 1.1, 3.8, 2.1 mm for the right, and 1.3, 3.0, 1.5 mm for the left kidney, respectively. The sigma in these three directions was 1.1, 3.1, 1.7 mm for the right, and 1.2, 2.9, 2.1 mm for the left kidney, respectively. For the diaphragm we estimated Sigma = 5.2 mm and sigma = 4.0 mm. No correlations were found between organ motion and height.Conclusions: The large inter-patient organ motion variations and the lack of correlation between motion and patient-related factors, suggest that individualized margin approaches might be required. (C) 2015 Elsevier Ireland Ltd. All rights reserved. Show less
