Validation of deformable image registration algorithms on CT images of<i>ex vivo</i>porcine bladders with fiducial markers

Wognum, S.; Heethuis, S.E.; Rosario, T.; Hoogeman, M.; Bel, Arjan

doi:10.1118/1.4883839

Cited by 47 publications

(46 citation statements)

References 46 publications

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“…However, an extensive validation of the complete anatomical correctness and the influence of possible incorrectness on dose accumulation is still an important challenge in RT [25] and beyond the scope of this study.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric advantages of proton therapy compared with photon therapy using an adaptive strategy in cervical cancer

et al. 2016

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Background Image-guided adaptive proton therapy (IGAPT) can potentially be applied to take into account interfraction motion while limiting organ at risk (OAR) dose in cervical cancer radiation therapy (RT). In this study, the potential dosimetric advantages of IGAPT compared with photonbased image-guided adaptive RT (IGART) were investigated. Material and methods For 13 cervical cancer patients, full and empty bladder planning computed tomography (CT) images and weekly CTs were acquired. Based on both primary clinical target volumes (pCTVs) [i.e. gross tumor volume (GTV), cervix, corpus-uterus and upper part of the vagina] on planning CTs, the pretreatment observed full range primary internal target volume (pITV) was interpolated to derive pITV subranges. Given corresponding ITVs (i.e. pITVs including lymph nodes), patient-specific photon and proton plan libraries were generated. Using all weekly CTs, IGART and IGAPT treatments were simulated by selecting library plans and recalculating the dose. For each recalculated IGART and IGAPT fraction, CTV (i.e. pCTV including lymph nodes) coverage was assessed and differences in fractionated substitutes of dose-volume histogram (DVH) parameters (V 15Gy , V 30Gy , V 45Gy , D mean , D 2cc ) for bladder, bowel and rectum were tested for significance (Wilcoxon signed-rank test). Also, differences in toxicity-related DVH parameters (rectum V 30Gy , bowel V 45Gy ) were approximated based on accumulated dose distributions. Results In 92% (96%) of all recalculated IGAPT (IGART) fractions adequate CTV coverage (V 95% 498%) was obtained. All dose parameters for bladder, bowel and rectum, except the fractionated substitute for rectum V 45Gy , were improved using IGAPT. Also, IGAPT reduced the mean dose to bowel, bladder and rectum significantly (p50.01). In addition, an average decrease of rectum V 30Gy and bowel V 45Gy indicated reductions in toxicity probabilities when using IGAPT. Conclusion This study demonstrates the feasibility of IGAPT in cervical cancer using a plan-library based plan-of-the-day approach. Compared to photon-based IGART, IGAPT maintains target coverage while significant dose reductions for the bladder, bowel and rectum can be achieved.

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Section: Discussionmentioning

confidence: 99%

Dosimetric advantages of proton therapy compared with photon therapy using an adaptive strategy in cervical cancer

et al. 2016

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“…Depending on the anatomical accuracy of this registration, the voxel-based summation of dose will closely match the actually delivered dose [14]. For bladder, it has been evaluated that a structure-based algorithm is sufficient for dose accumulation [27]. This has not been established for rectum and bowel cavity yet.…”

Section: Discussionmentioning

confidence: 99%

“…This has not been established for rectum and bowel cavity yet. In addition, intensity-based deformation algorithms are currently not accurate enough for dose accumulation purposes [14,27].…”

Section: Discussionmentioning

confidence: 99%

A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

et al. 2016

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Background Adaptive radiotherapy is introduced in the management of urinary bladder cancer to account for day-to-day anatomical changes. The purpose of this study was to determine whether an adaptive plan selection strategy using either the first four cone beam computed tomography scans (CBCT-based strategy) for plan creation, or the interpolation of bladder volumes on pretreatment CT scans (CT-based strategy), is better in terms of tumor control probability (TCP) and normal tissue sparing while taking the clinically applied fractionation schedules also into account. Material and methods With the CT-based strategy, a library of five plans was created. Patients received 55 Gy to the bladder tumor and 40 Gy to the non-involved bladder and lymph nodes, in 20 fractions. With the CBCT-based strategy, a library of three plans was created, and patients received 70 Gy to the tumor, 60 Gy to the bladder and 48 Gy to the lymph nodes, in 30-35 fractions. Ten patients were analyzed for each adaptive plan selection strategy. TCP was calculated applying the clinically used fractionation schedules, as well as a rescaling of the dose from 55 to 70 Gy for the CT-based strategy. For rectum and bowel, equivalent doses in 2 Gy fractions (EQD2) were calculated. Results The CBCT-based strategy resulted in a median TCP of 75%, compared to 49% for the CT-based strategy, the latter improving to 72% upon rescaling the dose to 70 Gy. A median rectum V30Gy (EQD2) of 26% [interquartile range (IQR): 8-52%] was found for the CT-based strategy, compared to 58% (IQR: 55-73%) for the CBCT-based strategy. Also the bowel doses were lower with the CT-based strategy. Conclusions Whereas the higher total bladder TCP for the CBCT-based strategy is due to prescription differences, the adaptive strategy based on CT scans results in the lowest rectum and bowel cavity doses.

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“…Several definitions of the HI are available. The HI that we used is defined as All dose and volume indexes were tested statistically with use of the Kruskal-Wallis test [16], which is a non-parametric method for testing differences among more than two groups; the significance of the trend for each of the dose and volume indexes that depended on the pitch angle error was confirmed by use of the Jonckheere-Terpstra test [17]. …”

Section: Methodsmentioning

confidence: 99%

Impact of pitch angle setup error and setup error correction on dose distribution in volumetric modulated arc therapy for prostate cancer

Takemura

Togawa

Yokoi

et al. 2016

Radiol Phys Technol

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In volumetric modulated arc therapy (VMAT) for prostate cancer, a positional and rotational error correction is performed according to the position and angle of the prostate. The correction often involves body leaning, and there is concern regarding variation in the dose distribution. Our purpose in this study was to evaluate the impact of body pitch rotation on the dose distribution regarding VMAT. Treatment plans were obtained retrospectively from eight patients with prostate cancer. The body in the computed tomography images for the original VMAT plan was shifted to create VMAT plans with virtual pitch angle errors of ±1.5 and ±3 degrees. Dose distributions for the tilted plans were recalculated with use of the same beam arrangement as that used for the original VMAT plan. The mean value of the maximum dose differences in the dose distributions between the original VMAT plan and the tilted plans was 2.98 ± 0.96%. The value of the homogeneity index for the planning target volume (PTV) had an increasing trend according to the pitch angle error, and the values of the D 95 for the PTV and D 2ml , V 50 , V 60 and V 70 for the rectum had decreasing trends (p<0.05). However, there was no correlation between differences in these indexes and the maximum dose difference. The pitch angle error caused by body leaning had little effect on the dose distribution, in contrast, the pitch angle correction reduced the effects of organ displacement and improved these indexes. Thus, the pitch angle setup error in VMAT for prostate cancer should be corrected. Keywordsvolumetric modulated arc therapy, prostate cancer, setup error, dose distribution, pitch angle 4

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Validation of deformable image registration algorithms on CT images ofex vivoporcine bladders with fiducial markers

Cited by 47 publications

References 46 publications

Dosimetric advantages of proton therapy compared with photon therapy using an adaptive strategy in cervical cancer

Dosimetric advantages of proton therapy compared with photon therapy using an adaptive strategy in cervical cancer

A biological modeling based comparison of two strategies for adaptive radiotherapy of urinary bladder cancer

Impact of pitch angle setup error and setup error correction on dose distribution in volumetric modulated arc therapy for prostate cancer

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