+publisher:"Delft University of Technology" +contributor:("Schaart, Dennis")

Delft University of Technology

1. Moret, Thijs (author). Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy.

Degree: 2019, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:4e5f6904-9c56-4b08-8168-8a12f29f8654

► In the field of radiation oncology, proton therapy is a relatively new technique. It shows a great advantage over conventional radiation therapy in the depth-dose… (more)

▼ In the field of radiation oncology, proton therapy is a relatively new technique. It shows a great advantage over conventional radiation therapy in the depth-dose relation, which results in the possibility to deliver dose far more concentrated at a specific depth. This in turn has the potential to spare the healthy tissue surrounding a tumour from receiving a very high dose. However, this depth-dose relation has the downside that it is very sensitive to small uncertainties in geometry and tissue composition, which are present in heterogeneous tissues such as lung tissue. Because of this sensitivity, it is essential that the dose delivery can be verified properly for these heterogeneous tissues, which requires highly accurate quality assurance. To improve this quality assurance, highly anthropomorphic phantoms could offer a solution. The currently commercially available phantoms however lack the high level of detail necessary, as these are produced using casting techniques. Thus a new production technique should be considered to create phantoms of greater heterogeneity and at a higher level of detail. A possible solution to this problem is to apply additive manufacturing, since this manufacturing technique can supposedly address both these issues. An important issue with the application of additive manufacturing is the lack of knowledge on the accuracy of 3D-printers. Next to the unknown accuracy, there are other challenges concerning additive manufacturing, such as the layered creation of objects and the material that is to be printed over an air cavity and the support structures this is associated with. The goal of this research is to explore the possibility to apply additive manufacturing in the creation of a phantom with a high level of detail and heterogeneity and the effect of the heterogeneous object on the quality of the Bragg peak. More specifically, simulations are performed on porous materials to quantify the degeneration of the Bragg peak. Also, a literature study on additive manufacturing will be performed, combined with the use of commercially available tabletop 3D-printers. Together, the capacity of the printer to create a high level of heterogeneity and the simulations performed on these heterogeneous structures, should give an indication on the feasibility to create a 3D-printed phantom for lung proton therapy. Advisors/Committee Members: Schaart, Dennis (mentor), Delft University of Technology (degree granting institution).

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APA (6^th Edition):

Moret, T. (. (2019). Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:4e5f6904-9c56-4b08-8168-8a12f29f8654

Chicago Manual of Style (16^th Edition):

Moret, Thijs (author). “Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy.” 2019. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:4e5f6904-9c56-4b08-8168-8a12f29f8654.

MLA Handbook (7^th Edition):

Moret, Thijs (author). “Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy.” 2019. Web. 14 Apr 2021.

Vancouver:

Moret T(. Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:4e5f6904-9c56-4b08-8168-8a12f29f8654.

Council of Science Editors:

Moret T(. Feasibility of 3D-printed phantoms for quantifying Bragg peak degeneration due to tissue heterogeneity in lung proton therapy. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:4e5f6904-9c56-4b08-8168-8a12f29f8654

Delft University of Technology

2. Vranas, Georgios (author). Performance evaluation of multipinhole μSPECT systems for short time frames.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:69b604da-2fa9-4a6e-8811-ddd4eb99931f

►

The need of image (frame) acquisitions within short time intervals is of major importance for preclinical SPECT imaging. The short frame times enable higher temporal… (more)

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The need of image (frame) acquisitions within short time intervals is of major importance for preclinical SPECT imaging. The short frame times enable higher temporal resolution which is required in bio-distribution and pharmacokinetic studies where fast dynamic imaging is performed. The present study evaluates and compares the performance of two different preclinical multipinhole SPECT systems (NanoScan, VECTor) for short frames acquisitions. Prior to the systems comparison, the comparison and selection of the best performing fast imaging mode provided by NanoScan system (Mediso) was performed. The fast imaging modes of this system provide acquisitions with 1,2 and 3 detector position around the animal bed. This comparison was performed by using uniform phantoms (syringes) and the rods of the NEMA NU4IQ phantom (frames: 6-30s). The down-sized version of NU4IQ phantom (SPECTIQ phantom) was used in this study to compare the performance of VECTor (MILabs) and NanoScan when performing acquisitions with short frame times (18s-600s, whole body scans). The quality of the acquired images was assessed in terms of absolute quantification (recovery coefficient), noise levels and visual evaluation. The quantification with the NanoScan was accurate (±5%) regardless of times frames duration and activity concentrations when imaging large structures. The increase in number of detector positions yielded images with lower noise levels. In the case of small structures, acquisition with 3 detector positions (Semi-3 mode) appeared to provide more accurate activity recovery compared to acquisitions with 1 (stationary mode) and 2 detector positions (Semi-2 mode). Especially in the case of the 2mm diameter rod of the NU4IQ phantom, the Semi-3 mode appears to provide significantly more accurate activity recovery (30s frame). The systems comparison showed activity recovery with up to 5% deviation from the dose calibrator measurement when imaging the uniform region of SPECTIQ phantom (d = 21mm). Both systems could recover the three largest rods (d = 1.5, 1.0, 0.75mm) for the longest frames used(180,360,600s). None of the systems could recover the two smallest rods of the phantom (d=0.5,0.35mm). As the frame time decreased, both systems could recover less number of rods. VECTor appeared to provide higher activity recovery than NanoScan for the three largest rods of the phantom. However, as the frame time decreased the differences became less significant. Furthermore, VECTor provided and 22.2% and 46.6% less spillover in airand water-filled phantom regions (after reaching convergence) than NanoScan did. The performances of two preclinical SPECT systems (NanoScan, VECTor) for short time acquisitionswere compared. The conducted experiments showed that the systems perform equally when conducting short frames imaging. Furthermore, the fast imaging mode of NanoScan employing three detector positions showed better performance than the other two fast imaging modes provided by this system.

Biomedical Engineering

Advisors/Committee Members: Schaart, Dennis (mentor), Goorden, Marlies (mentor), Delft University of Technology (degree granting institution).

Subjects/Keywords: Preclinical SPECT; performance evaluation; Image Quality; Phantom

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Vranas, G. (. (2017). Performance evaluation of multipinhole μSPECT systems for short time frames. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:69b604da-2fa9-4a6e-8811-ddd4eb99931f

Chicago Manual of Style (16^th Edition):

Vranas, Georgios (author). “Performance evaluation of multipinhole μSPECT systems for short time frames.” 2017. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:69b604da-2fa9-4a6e-8811-ddd4eb99931f.

MLA Handbook (7^th Edition):

Vranas, Georgios (author). “Performance evaluation of multipinhole μSPECT systems for short time frames.” 2017. Web. 14 Apr 2021.

Vancouver:

Vranas G(. Performance evaluation of multipinhole μSPECT systems for short time frames. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:69b604da-2fa9-4a6e-8811-ddd4eb99931f.

Council of Science Editors:

Vranas G(. Performance evaluation of multipinhole μSPECT systems for short time frames. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:69b604da-2fa9-4a6e-8811-ddd4eb99931f

Delft University of Technology

3. van Oossanen, Rogier (author). Development of a 3D-printed phantom for proton therapy.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:994f571f-8a71-4666-9d29-8c79a59f9d10

►

Proton therapy is a relatively new technique in the field of radiation oncology. The advantage of using protons can be illustrated by the depth-dose relation,… (more)

▼

Proton therapy is a relatively new technique in the field of radiation oncology. The advantage of using protons can be illustrated by the depth-dose relation, which results in a more concentrated dose at a specific depth and thus potentially less dose in the surrounding healthy tissue compared to conventional photon therapy. However, this depth-dose relation also makes the dose delivery very sensitive to small geometric uncertainties. Because of this sensitivity, high accuracy of the quality assurance (QA) is essential. QA can be used to test robustness of the system when dealing with small geometric uncertainties such as air gaps. Most of the QA protocols use phantoms to test the clinical treatment protocol or the complete treatment chain. To accurately simulate a patient, the phantom should resemble the human anatomy as well as tissue composition its interaction properties with ionizing radiation. In order to be optimally test the accuracy of the treatment system, the phantom should include small air gaps, density gradients in soft and bone tissue-substitutes and millimeter-scale structures. Currently phantoms are produced using casting techniques, which limits the possibilities to include small features or density gradients. This causes the phantoms available to lack the level of detail required for proton therapy QA. One important source of errors in current treatment planning is the usage of a mono energy CT-scan of the patient for treatment planning, which measures the photon attenuation and converts this to Hounsfield Units (HU). For proton therapy, the HU is converted to the proton stopping power ratio (SPR) of the tissue compared to water, using a HU-SPR conversion model. Since there is no one-to-one relation between HU and SPR, this inevitably leads to errors, for example when tissues with the same HU have a slightly different SPR. Therefore dual-energy CT (DECT) has been proposed as a replacement for conventional mono energetic CT in proton treatment planning. The information acquired by the DECT is used in the Bethe formula to calculate the SPR directly, making the HU-SPR calibration curve obsolete, thus improving the accuracy of treatment planning. The goal of this study is to explore the possibilities of designing an anthropomorphic phantom with small geometric features using a 3D-printer. By using a 3D-printer we can print the structure of the phantom at the millimeter-scale. Multiple materials can be mixed while printing, making it easier to adjust material properties such as density. Since DECT could improve proton treatment planning, we will aim to use materials that will be compatible with DECT-based HU-SPR conversion methods, so that these materials will be treated similar to that of human tissue by the treatment system. This way, the phantom should have the same SPR as human tissue, as well as covering small geometric details.

Medical Physics & Technology

Advisors/Committee Members: Schaart, Dennis (mentor), Wang, C.C.L. (mentor), Perko, Zoltan (mentor), Delft University of Technology (degree granting institution).

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

van Oossanen, R. (. (2017). Development of a 3D-printed phantom for proton therapy. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:994f571f-8a71-4666-9d29-8c79a59f9d10

Chicago Manual of Style (16^th Edition):

van Oossanen, Rogier (author). “Development of a 3D-printed phantom for proton therapy.” 2017. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:994f571f-8a71-4666-9d29-8c79a59f9d10.

MLA Handbook (7^th Edition):

van Oossanen, Rogier (author). “Development of a 3D-printed phantom for proton therapy.” 2017. Web. 14 Apr 2021.

Vancouver:

van Oossanen R(. Development of a 3D-printed phantom for proton therapy. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:994f571f-8a71-4666-9d29-8c79a59f9d10.

Council of Science Editors:

van Oossanen R(. Development of a 3D-printed phantom for proton therapy. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:994f571f-8a71-4666-9d29-8c79a59f9d10

Delft University of Technology

4. Ghesquière-Diérickx, Laura (author). Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:0183c922-76a4-4507-96dd-38362e27da0a

►

In medical images intratumour heterogeneity well translates specific cancer cells properties in a fast and non-invasive way. Medical community and researchers have developed proper tools… (more)

Subjects/Keywords: pet; phantom; heterogeneity; Positron emission tomography

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ghesquière-Diérickx, L. (. (2017). Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:0183c922-76a4-4507-96dd-38362e27da0a

Chicago Manual of Style (16^th Edition):

Ghesquière-Diérickx, Laura (author). “Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom.” 2017. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:0183c922-76a4-4507-96dd-38362e27da0a.

MLA Handbook (7^th Edition):

Ghesquière-Diérickx, Laura (author). “Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom.” 2017. Web. 14 Apr 2021.

Vancouver:

Ghesquière-Diérickx L(. Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:0183c922-76a4-4507-96dd-38362e27da0a.

Council of Science Editors:

Ghesquière-Diérickx L(. Improvement of tumour heterogeneity quantification in PET images: A study to design and develop a new PET heterogeneous phantom. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:0183c922-76a4-4507-96dd-38362e27da0a

Delft University of Technology

5. den Boer, Erik (author). Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy.

Degree: 2020, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:b3b46f7a-a997-4905-ab77-ad4c54617e9b

► Pencil beam scanning is becoming a more common treatment modality. However, its ability to deal with moving targets is known to be limited, as beam… (more)

▼ Pencil beam scanning is becoming a more common treatment modality. However, its ability to deal with moving targets is known to be limited, as beam motion and target motion can reinforce each other, deteriorating the planned dose distribution in what is called the interplay effect. Literature concerning breathing motion usually investigates regular patterns. This work aims to investigate the magnitude of the interplay effect when considering irregular breathing signals. In silico calculations of dose distributions were made in the treatment planning system RayStation (version 7.99), using an XCAT phantom with 50 CT phases to model moving patient anatomy. An interplay calculator was included in RayStation, allowing calculation of disturbed doses based on a treatment plan and an irradiation time model for a proton therapy accelerator. The target investigated was a spherical liver tumour with 5cm diameter, irradiated with two beams delivering a prescription dose of 63 Gy. Plans without and with 5x layered repainting were created. Clinically realistic regular breathing patterns were generated to establish a baseline, after which irregularities were introduced. The basic form for all patterns was a sin⁴ signal, with regular signal amplitudes ranging from 6 to 18 mm, period ranging from 3 to 4 s and phase between 0 and 2π rad. Considered irregularities were baseline shifts up to 34 mm, changing amplitudes between 6 and 18 mm, changing periods between 1.6 and 5.2 s and combinations. Evaluation was done by looking at dose homogeneity HI₅ and the fraction of the CTV volume that received a dose outside of the clinical limits of 95% and 107%, V₁₀₇/95. For the regular patterns, both a systematic and a randomised analysis were carried out. For irregular patterns, only a systematic analysis was carried out. The mean HI₅ was found to be 31% for regular patterns; the means of all irregular patterns stay below this, even though the size of the irregularities for some breathing patterns was very large. The mean V₁₀₇/95 was found to be 0.7 for regular patterns. Irregularities did not cause further deterioration. Five times layered repainting causes a statistically significant decrease in magnitude of the interplay effect across all breathing patterns by 50-80%, but is approximately 50% less effective against baseline shift than against other types of breathing. Interplay effect size correlates strongly with amplitude, but this correlation can be obscured because period and phase introduce very large variance. The interplay effect in general is large for investigated target size, prescription dose, beam configuration and machine performance. It can cause up to 100% of the CTV to receive a clinically unacceptable dose and lead to large inhomogeneities. Irregular breathing was not found to be notably worse. Repainting is effective, even against irregular breathing, but baseline shifts can undermine its effectiveness. Separately considering breathing irregularities for tumours similar to that investigated here is deemed of low… Advisors/Committee Members: Perko, Zoltan (mentor), Goorden, Marlies (graduation committee), Schaart, Dennis (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: Proton Therapy; Irregular breathing; Pencil beam scanning; Interplay effect

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

den Boer, E. (. (2020). Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:b3b46f7a-a997-4905-ab77-ad4c54617e9b

Chicago Manual of Style (16^th Edition):

den Boer, Erik (author). “Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy.” 2020. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:b3b46f7a-a997-4905-ab77-ad4c54617e9b.

MLA Handbook (7^th Edition):

den Boer, Erik (author). “Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy.” 2020. Web. 14 Apr 2021.

Vancouver:

den Boer E(. Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy. [Internet] [Masters thesis]. Delft University of Technology; 2020. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:b3b46f7a-a997-4905-ab77-ad4c54617e9b.

Council of Science Editors:

den Boer E(. Irregular breathing in proton therapy: The effect of irregular breathing on the interplay effect in pencil beam scanning proton therapy. [Masters Thesis]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:b3b46f7a-a997-4905-ab77-ad4c54617e9b

Delft University of Technology

6. Undetermined, U. (author). Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:b69226f9-c00b-4137-819c-7e6a6ea4aea4

► At the Antoni van Leeuwenhoek Hospital/Dutch Cancer Institute (NKI-AvL) in Amsterdam, inter-fractional anatomical changes during the course of radiotherapy are monitored using cone beam CT… (more)

▼ At the Antoni van Leeuwenhoek Hospital/Dutch Cancer Institute (NKI-AvL) in Amsterdam, inter-fractional anatomical changes during the course of radiotherapy are monitored using cone beam CT scans, taken prior to irradiation. These scans are assessed visually, and the fractions are scored according to a 'traffic light protocol'. Based on the magnitude of change, a green, yellow, orange or red colour, in increasing order of severity, is assigned to the fraction. The goal of this work was to ascertain if the colour of the traffic lights, which were assumed to be indicators of anatomical change, correlate to changes in dosimetry for H\&N VMAT treatments, as well as lung IMRT treatments. The in-vivo EPID dose was reconstructed in the patient for each fraction, using a back-projection algorithm that is used clinically at the NKI. Calibrated CBCTs of each fraction were obtained using DIR or anti-scatter grid methods researched at the NKI, which were then imported to a TPS to obtain the fraction dose. These two modes of dosimetry were compared against each other, as well as against the traffic light colours for H\&N treatments. For lung treatments, due to unavailability of CBCT based dose data, only EPID dosimetry was used; two different models of the back-projection algorithm were compared in this case. γ index and DVH metrics were used to express deviation in the dose distributions. Deviations over successive fractions for 18 H\&N treatments were studied. The traffic light protocol correlated poorly with CBCT based dose and EPID reconstructed dose (ρ = 0.33 and 0.35 respectively). The CBCT and EPID dose correlated with each other quite strongly (ρ = 0.72), however the EPID dose was more sensitive in its fluctuations. Deviations for 98 IMRT lung fractions were studied. The traffic light protocol correlated even more poorly with the EPID reconstructed dose than in the H\&N study (ρ = 0.18). The calculated transmission model of the EPID was found to exaggerate the deviations in comparison to the measured transmission model. Since VMAT innately uses the calculated transmission model, this explains the sensitivity of the EPID results seen in the H\&N study. We have shown that the traffic light protocol does not correlate with dosimetric changes, due to differences in assessment criteria. 15 out of 18 H\&N treatments showed moderate (ρ ≥ 0.4), if not strong, correlations between deviations of EPID reconstructed dose and CBCT based dose, strengthening the EPID's applicability for in-vivo dosimetry. Advisors/Committee Members: Schaart, Dennis (mentor), Mans, Anton (mentor), Olaciregui-Ruiz, Igor (mentor), Vos, Frans (graduation committee), Perko, Zoltan (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: Radiotherapy; epid dosimetry; cone beam CT

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Undetermined, U. (. (2017). Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:b69226f9-c00b-4137-819c-7e6a6ea4aea4

Chicago Manual of Style (16^th Edition):

Undetermined, U (author). “Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study.” 2017. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:b69226f9-c00b-4137-819c-7e6a6ea4aea4.

MLA Handbook (7^th Edition):

Undetermined, U (author). “Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study.” 2017. Web. 14 Apr 2021.

Vancouver:

Undetermined U(. Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:b69226f9-c00b-4137-819c-7e6a6ea4aea4.

Council of Science Editors:

Undetermined U(. Correlating scored daily anatomical changes to in-vivo EPID dosimetry and cone beam CT based dose calculations: A retrospective study. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:b69226f9-c00b-4137-819c-7e6a6ea4aea4

Delft University of Technology

7. Bennan, Amit (author). Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:2c0ade14-fc3a-413d-bebc-a6f9ff71fb25

► Introduction: High Dose Rate (HDR) Brachytherapy is a radiotherapy modality that involves temporarily introducing a highly radioactive source into the target volume with the use… (more)

▼ Introduction: High Dose Rate (HDR) Brachytherapy is a radiotherapy modality that involves temporarily introducing a highly radioactive source into the target volume with the use of an applicator. With respect to HDR brachytherapy for prostate cancer, an 192Iridium source is driven into the target volume through catheters implanted into the prostate. The dose delivered to a point in the prostate depends on the time the source dwells at a given position. Treatment planning for brachytherapy involve the optimization of dwell times and dwell positions. The aim of the treatment plan is to deliver the prescribed dose to the target volume, the prostate, while minimizing the dose to the organs at risk (OAR), namely the urethra, bladder and rectum. In current clinical practice, the process of treatment planning involves the manual manipulation of the parameters of an optimizer until the desired dose distribution is achieved. This implies that the plan quality depends on the experience of the planner, and there is variation in plan quality between planners. The aim of this project was to develop an automated treatment planning system that would able to generate clinically acceptable plans with minimal human intervention. The brachytherapy treatment planning module is named B-iCycle and may be integrated in the future with the treatment planning software suite, called Erasmus-iCycle, developed at the Erasmus MC. Materials and methods: At the core of the treatment planning system (TPS) is a precise and fast dose engine that is able to simulate the dose to be delivered. In this project, we employ the TG-43 dose calculation formalism as it is the most widely implemented method in dose engines for brachytherapy treatment planning systems. The dose engine is then verified against the dose engine of the clinical treatment planning system. B-iCycle uses the 2-phase ϵ-constraint (2pϵc) algorithm to optimize the dwell times and positions. The 2pϵc algorithm requires a ‘wish-list’, which encapsulates the treatment protocol as goals and constraints for each critical structure. For this project three treatment protocols were chosen, four fractions of 9.5 Gy, single fraction of 19 Gy and single fraction of 20 Gy, and wish-lists were generated for each protocol. Three patient groups with different catheter geometries were selected. Treatment plans were generated for each patient and compared against the plans that were generated, for the same patients, in the clinic. The treatment plans that were generated in B-iCycle were then exported to the clinical treatment planning system (Oncentra from Elekta) to obtain the dose characteristics. The plans were compared based on the dose characteristics and the Conformity Index (COIN). The plans were also verified by a radiation oncologist. Results: The TG-43 dose engine was successfully verified against the clinical dose engine. The Gamma analysis showed that only 0.68% of the voxels failed the gamma analysis and these voxels were located within the catheters therefore they can be ignored as… Advisors/Committee Members: Schaart, Dennis (mentor), Breedveld, S. (mentor), Kolkman-Deurloo, I.K.K. (mentor), Heijman, B.J.M. (mentor), Lathouwers, Danny (mentor), Goorden, Marlies (mentor), Delft University of Technology (degree granting institution).

Subjects/Keywords: brachytherapy; Treatment Planning; prostate cancer; HDR

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bennan, A. (. (2017). Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:2c0ade14-fc3a-413d-bebc-a6f9ff71fb25

Chicago Manual of Style (16^th Edition):

Bennan, Amit (author). “Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer.” 2017. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:2c0ade14-fc3a-413d-bebc-a6f9ff71fb25.

MLA Handbook (7^th Edition):

Bennan, Amit (author). “Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer.” 2017. Web. 14 Apr 2021.

Vancouver:

Bennan A(. Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:2c0ade14-fc3a-413d-bebc-a6f9ff71fb25.

Council of Science Editors:

Bennan A(. Automated Treatment Planning in HDR Brachytherapy for Prostate Cancer. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:2c0ade14-fc3a-413d-bebc-a6f9ff71fb25

Delft University of Technology

8. van Aert, Emy (author). Gel dosimetry for a MR-linac: magnetic field and time dependency.

Degree: 2020, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:4408f7c6-d16f-4cab-90c0-60dbf03d8a27

► The goal of this research was to perform a 3D end-to-end test on a MR-linac to check the whole workflow using a clinical treatment plan.… (more)

▼ The goal of this research was to perform a 3D end-to-end test on a MR-linac to check the whole workflow using a clinical treatment plan. Dosimetric gel was used to obtain 3D spatial information, with the phantom in the same position for irradiation and scanning. In order to achieve this, fundamental elements of gel dosimetry needed to be investigated. In the MR-linac, irradiation is delivered in the presence of a permanent magnetic field. Therefore, the dosimetric response within a 1.5 T magnetic field should be validated. It is also important to investigate the time-dependence of the gel. It is preferable to read-out the gels within approximately one hour, so that the phantom does not have to be moved. Ideally, scanning and irradiation would be done at the same time, to see the dynamical dose delivery. The VIPAR gel was used for this research. The experiments demonstrated that R2 values for doses irradiated with magnetic field were the same as R2 values for the same dose irradiated without magnetic field. R2 values are still proportional to the dose. It was also shown that it is possible to scan the phantom within 20 minutes after irradiation. Sensitivity is at its highest after approximately 8 hours and stays stable afterwards, so scanning after 8 hours will improve the read-out accuracy. It was also possible to make a fit for the R2 versus time plots, which makes it possible to correct for change over time. The fit can be divided in two linear parts if time is plotted on a logarithmic scale, one fit for the time points before 7 hours, one for the time points after 7 hours. The partial doses acquired by the gel during radiation delivery were estimated. The equivalent R2 values then agreed with the extrapolated fit to within 4%. This is a good indication that dynamic gel (4D) dosimetry may be achievable. A protocol for a relative end-to-end test was also developed. From the preliminary results, it appeared that a relative end-to-end test can be performed with the read-out of gel within 1 hour. A new MR sequence needs to be developed. For this end-to-end test, the sequence needs to scan a larger volume with a higher resolution, therefore, the scan time will increase and real-time dosimetry will not be possible. Changing the MR sequence might also change the optimal irradiation-scanning interval and the R2 versus time curve. To perform absolute dosimetry, an extra calibration would be required. Advisors/Committee Members: Denkova, Antonia (mentor), Wolthaus, Jochem (mentor), Woodings, Simon (mentor), Schaart, Dennis (graduation committee), Djanashvili, Kristina (graduation committee), Delft University of Technology (degree granting institution).

Subjects/Keywords: gel dosimetry; MR-linac; magnetic field

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

van Aert, E. (. (2020). Gel dosimetry for a MR-linac: magnetic field and time dependency. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:4408f7c6-d16f-4cab-90c0-60dbf03d8a27

Chicago Manual of Style (16^th Edition):

van Aert, Emy (author). “Gel dosimetry for a MR-linac: magnetic field and time dependency.” 2020. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:4408f7c6-d16f-4cab-90c0-60dbf03d8a27.

MLA Handbook (7^th Edition):

van Aert, Emy (author). “Gel dosimetry for a MR-linac: magnetic field and time dependency.” 2020. Web. 14 Apr 2021.

Vancouver:

van Aert E(. Gel dosimetry for a MR-linac: magnetic field and time dependency. [Internet] [Masters thesis]. Delft University of Technology; 2020. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:4408f7c6-d16f-4cab-90c0-60dbf03d8a27.

Council of Science Editors:

van Aert E(. Gel dosimetry for a MR-linac: magnetic field and time dependency. [Masters Thesis]. Delft University of Technology; 2020. Available from: http://resolver.tudelft.nl/uuid:4408f7c6-d16f-4cab-90c0-60dbf03d8a27

Delft University of Technology

9. Groenendijk, Celebrity (author). Ex vivo Validation of PET Imaging by 3D-printed Phantoms.

Degree: 2019, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:b5ba4bc4-5c33-4cb7-82cd-08878bc01800

Medical Physics & Technology Advisors/Committee Members: Schaart, Dennis (mentor), Delft University of Technology (degree granting institution).

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Groenendijk, C. (. (2019). Ex vivo Validation of PET Imaging by 3D-printed Phantoms. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:b5ba4bc4-5c33-4cb7-82cd-08878bc01800

Chicago Manual of Style (16^th Edition):

Groenendijk, Celebrity (author). “Ex vivo Validation of PET Imaging by 3D-printed Phantoms.” 2019. Masters Thesis, Delft University of Technology. Accessed April 14, 2021. http://resolver.tudelft.nl/uuid:b5ba4bc4-5c33-4cb7-82cd-08878bc01800.

MLA Handbook (7^th Edition):

Groenendijk, Celebrity (author). “Ex vivo Validation of PET Imaging by 3D-printed Phantoms.” 2019. Web. 14 Apr 2021.

Vancouver:

Groenendijk C(. Ex vivo Validation of PET Imaging by 3D-printed Phantoms. [Internet] [Masters thesis]. Delft University of Technology; 2019. [cited 2021 Apr 14]. Available from: http://resolver.tudelft.nl/uuid:b5ba4bc4-5c33-4cb7-82cd-08878bc01800.

Council of Science Editors:

Groenendijk C(. Ex vivo Validation of PET Imaging by 3D-printed Phantoms. [Masters Thesis]. Delft University of Technology; 2019. Available from: http://resolver.tudelft.nl/uuid:b5ba4bc4-5c33-4cb7-82cd-08878bc01800

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