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Papers by Tara van de water

Research paper thumbnail of A balanced team generating model

European Journal of Operational Research, 2007

This paper introduces a general team balancing model. It first summarizes existing balancing meth... more This paper introduces a general team balancing model. It first summarizes existing balancing methods. It is shown that for these methods it is difficult to meet all the conditions posed by Belbin on balanced teams. This mainly is caused by the complexity of the balancing problem. A mathematical model is then introduced that gives one the opportunity to take into account these conditions in mutual coherence and to generate a balanced team in terms of Belbin. A practical application is given.

Research paper thumbnail of Delineation guidelines for organs at risk involved in radiation-induced salivary dysfunction and xerostomia

Radiotherapy and Oncology, 2009

Background and purpose: It is believed that minimizing inconsistencies in OAR-volume definition w... more Background and purpose: It is believed that minimizing inconsistencies in OAR-volume definition will help to improve adequate reporting and interpreting of radiation treatment results. The aim of this paper is to introduce computed tomography (CT)-based delineation guidelines for organs at risk (OARs) in the head and neck area, associated with radiation-induced salivary dysfunction and xerostomia. Material and methods: After analyses of the human anatomy of the head and neck area, computed tomography (CT)-based guidelines for delineation of the most relevant OARs were described by a panel of experts.

Research paper thumbnail of Potential Benefits of Scanned Intensity-Modulated Proton Therapy Versus Advanced Photon Therapy With Regard to Sparing of the Salivary Glands in Oropharyngeal Cancer

International Journal of Radiation Oncology Biology Physics, 2011

To test the hypothesis that scanned intensity-modulated proton therapy (IMPT) results in a signif... more To test the hypothesis that scanned intensity-modulated proton therapy (IMPT) results in a significant dose reduction to the parotid and submandibular glands as compared with intensity-modulated radiotherapy with photons (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for oropharyngeal cancer. In addition, we investigated whether the achieved dose reductions would theoretically translate into a reduction of salivary dysfunction and xerostomia. Ten patients with N0 oropharyngeal carcinoma were used. The intensity-modulated plans delivered simultaneously 70 Gy to the boost planning target volume (PTV2) and 54 Gy to the elective nodal areas (PTV1). The 3D-CRT technique delivered sequentially 70 Gy and 46 Gy to PTV2 and PTV1, respectively. Normal tissue complication probabilities were calculated for salivary dysfunction and xerostomia. Planning target volume coverage results were similar for IMPT and IMRT. Intensity-modulated proton therapy clearly improved the conformity. The 3D-CRT results were inferior to these results. The mean dose to the parotid glands by 3D-CRT (50.8 Gy), IMRT (25.5 Gy), and IMPT (16.8 Gy) differed significantly. For the submandibular glands no significant differences between IMRT and IMPT were found. The dose reductions obtained with IMPT theoretically translated into a significant reduction in normal tissue complication probability. Compared with IMRT and 3D-CRT, IMPT improved sparing of the organs at risk, while keeping similar target coverage results. The dose reductions obtained with IMPT vs. IMRT and 3D-CRT varied widely per individual patient. Intensity-modulated proton therapy theoretically translated into a clinical benefit for most cases, but this requires clinical validation.

Research paper thumbnail of 184 oral DYSPHAGIA REDUCTION WITH OPTIMIZED PHOTON AND PROTON INTENSITY-MODULATED RADIOTHERAPY FOR HEAD AND NECK CANCER

Radiotherapy and Oncology, 2011

Research paper thumbnail of 411 poster INTENSITY-MODULATED PROTON THERAPY WITH A REDUCED SPOT SIZE IMPROVES SALIVARY GLAND-SPARING IN OROPHARYNX CANCER

Radiotherapy and Oncology, 2011

Research paper thumbnail of Delineation of organs at risk involved in swallowing for radiotherapy treatment planning

Radiotherapy and Oncology

Background and purpose: Radiotherapy, alone or combined with chemotherapy, is a treatment modalit... more Background and purpose: Radiotherapy, alone or combined with chemotherapy, is a treatment modality used frequently in head and neck cancer. In order to report, compare and interpret the sequelae of radiation treatment adequately, it is important to delineate organs at risk (OARs) according to well-defined and uniform guidelines. The aim of this paper was to present our institutional Computed Tomography (CT)-based delineation guidelines for organs in the head and neck at risk for radiation-induced swallowing dysfunction (SWOARs). Material and methods: After analyses of the human anatomy of the head and neck area and literature review, CT-based guidelines for delineation of the most relevant SWOARs were described by a panel of experts.

Research paper thumbnail of 410 poster IMPACT OF SYSTEMATIC ALIGNMENT ERRORS ON SPOTSCANNED INTENSITY-MODULATED PROTON THERAPY FOR HEAD AND NECK CANCER

Radiotherapy and Oncology, 2011

averaged a maximum of 34.3 Gy and a minimum of 24 Gy. The mean time to delivery a single treatmen... more averaged a maximum of 34.3 Gy and a minimum of 24 Gy. The mean time to delivery a single treatment was 6.9 min. The shortest time (4 min) was measured for a plan with single metastasis, while the longest time (10.2 min) for a plan with three metastases. The mean time to perform and evaluate the MVCT was 5 min (range 4-8 min).From a clinical point of view, radiological response was rapid in the patients with adenocarcinoma metastases, while slight reduction or stabilization occurred in those patients with melanoma and renal carcinoma. At a mean follow up of 14.4 months (range 1-23), the overall median survival was 14.4 months, with one-year survival rate of 45%. At last follow up local control was 81%, with radiological evidence of radionecrosis in 2 pts. Only eight lesions failed in the treated volume or in its immediate margins. No major acute toxicity occurred. Although four patient had transient general seizures on the treatment day of RT, they were soon managed with an administration of a corticosteroid. As to chronic toxicity, one patient underwent surgical resection for localized radiation necrosis after 3 months from RT. Except for the 1 patient, no other major chronic CNS toxicity was recorded in the 21 patients evaluated. Conclusions: Precise stereotactic radiotherapy was effective and safe in treatment of oligometastatic brain lesions, and allow the treatment salgave with local radiotherapy or whole brain RT of brain recurrence. Taking into consideration significant prognostic factors should help us to choose an appropriate way of treatment for each patient, and further investigation with respect to the "oligometastases situation" might offer novel findings of importance that could be incorporated in designing a new-stage treatment strategy with stereotactic radiation treatment. 409 poster ENERGY SPECTRUM UNCERTAINTIES IN RADIATION THERAPY WITH LASER ACCELERATED PARTICLES

Research paper thumbnail of Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

Fuel and Energy Abstracts

To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could... more To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality of life during and after radiotherapy treatment.

Research paper thumbnail of A balanced team generating model

European Journal of Operational Research, 2007

This paper introduces a general team balancing model. It first summarizes existing balancing meth... more This paper introduces a general team balancing model. It first summarizes existing balancing methods. It is shown that for these methods it is difficult to meet all the conditions posed by Belbin on balanced teams. This mainly is caused by the complexity of the balancing problem. A mathematical model is then introduced that gives one the opportunity to take into account these conditions in mutual coherence and to generate a balanced team in terms of Belbin. A practical application is given.

Research paper thumbnail of Delineation guidelines for organs at risk involved in radiation-induced salivary dysfunction and xerostomia

Radiotherapy and Oncology, 2009

Background and purpose: It is believed that minimizing inconsistencies in OAR-volume definition w... more Background and purpose: It is believed that minimizing inconsistencies in OAR-volume definition will help to improve adequate reporting and interpreting of radiation treatment results. The aim of this paper is to introduce computed tomography (CT)-based delineation guidelines for organs at risk (OARs) in the head and neck area, associated with radiation-induced salivary dysfunction and xerostomia. Material and methods: After analyses of the human anatomy of the head and neck area, computed tomography (CT)-based guidelines for delineation of the most relevant OARs were described by a panel of experts.

Research paper thumbnail of Potential Benefits of Scanned Intensity-Modulated Proton Therapy Versus Advanced Photon Therapy With Regard to Sparing of the Salivary Glands in Oropharyngeal Cancer

International Journal of Radiation Oncology Biology Physics, 2011

To test the hypothesis that scanned intensity-modulated proton therapy (IMPT) results in a signif... more To test the hypothesis that scanned intensity-modulated proton therapy (IMPT) results in a significant dose reduction to the parotid and submandibular glands as compared with intensity-modulated radiotherapy with photons (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) for oropharyngeal cancer. In addition, we investigated whether the achieved dose reductions would theoretically translate into a reduction of salivary dysfunction and xerostomia. Ten patients with N0 oropharyngeal carcinoma were used. The intensity-modulated plans delivered simultaneously 70 Gy to the boost planning target volume (PTV2) and 54 Gy to the elective nodal areas (PTV1). The 3D-CRT technique delivered sequentially 70 Gy and 46 Gy to PTV2 and PTV1, respectively. Normal tissue complication probabilities were calculated for salivary dysfunction and xerostomia. Planning target volume coverage results were similar for IMPT and IMRT. Intensity-modulated proton therapy clearly improved the conformity. The 3D-CRT results were inferior to these results. The mean dose to the parotid glands by 3D-CRT (50.8 Gy), IMRT (25.5 Gy), and IMPT (16.8 Gy) differed significantly. For the submandibular glands no significant differences between IMRT and IMPT were found. The dose reductions obtained with IMPT theoretically translated into a significant reduction in normal tissue complication probability. Compared with IMRT and 3D-CRT, IMPT improved sparing of the organs at risk, while keeping similar target coverage results. The dose reductions obtained with IMPT vs. IMRT and 3D-CRT varied widely per individual patient. Intensity-modulated proton therapy theoretically translated into a clinical benefit for most cases, but this requires clinical validation.

Research paper thumbnail of 184 oral DYSPHAGIA REDUCTION WITH OPTIMIZED PHOTON AND PROTON INTENSITY-MODULATED RADIOTHERAPY FOR HEAD AND NECK CANCER

Radiotherapy and Oncology, 2011

Research paper thumbnail of 411 poster INTENSITY-MODULATED PROTON THERAPY WITH A REDUCED SPOT SIZE IMPROVES SALIVARY GLAND-SPARING IN OROPHARYNX CANCER

Radiotherapy and Oncology, 2011

Research paper thumbnail of Delineation of organs at risk involved in swallowing for radiotherapy treatment planning

Radiotherapy and Oncology

Background and purpose: Radiotherapy, alone or combined with chemotherapy, is a treatment modalit... more Background and purpose: Radiotherapy, alone or combined with chemotherapy, is a treatment modality used frequently in head and neck cancer. In order to report, compare and interpret the sequelae of radiation treatment adequately, it is important to delineate organs at risk (OARs) according to well-defined and uniform guidelines. The aim of this paper was to present our institutional Computed Tomography (CT)-based delineation guidelines for organs in the head and neck at risk for radiation-induced swallowing dysfunction (SWOARs). Material and methods: After analyses of the human anatomy of the head and neck area and literature review, CT-based guidelines for delineation of the most relevant SWOARs were described by a panel of experts.

Research paper thumbnail of 410 poster IMPACT OF SYSTEMATIC ALIGNMENT ERRORS ON SPOTSCANNED INTENSITY-MODULATED PROTON THERAPY FOR HEAD AND NECK CANCER

Radiotherapy and Oncology, 2011

averaged a maximum of 34.3 Gy and a minimum of 24 Gy. The mean time to delivery a single treatmen... more averaged a maximum of 34.3 Gy and a minimum of 24 Gy. The mean time to delivery a single treatment was 6.9 min. The shortest time (4 min) was measured for a plan with single metastasis, while the longest time (10.2 min) for a plan with three metastases. The mean time to perform and evaluate the MVCT was 5 min (range 4-8 min).From a clinical point of view, radiological response was rapid in the patients with adenocarcinoma metastases, while slight reduction or stabilization occurred in those patients with melanoma and renal carcinoma. At a mean follow up of 14.4 months (range 1-23), the overall median survival was 14.4 months, with one-year survival rate of 45%. At last follow up local control was 81%, with radiological evidence of radionecrosis in 2 pts. Only eight lesions failed in the treated volume or in its immediate margins. No major acute toxicity occurred. Although four patient had transient general seizures on the treatment day of RT, they were soon managed with an administration of a corticosteroid. As to chronic toxicity, one patient underwent surgical resection for localized radiation necrosis after 3 months from RT. Except for the 1 patient, no other major chronic CNS toxicity was recorded in the 21 patients evaluated. Conclusions: Precise stereotactic radiotherapy was effective and safe in treatment of oligometastatic brain lesions, and allow the treatment salgave with local radiotherapy or whole brain RT of brain recurrence. Taking into consideration significant prognostic factors should help us to choose an appropriate way of treatment for each patient, and further investigation with respect to the "oligometastases situation" might offer novel findings of importance that could be incorporated in designing a new-stage treatment strategy with stereotactic radiation treatment. 409 poster ENERGY SPECTRUM UNCERTAINTIES IN RADIATION THERAPY WITH LASER ACCELERATED PARTICLES

Research paper thumbnail of Using a Reduced Spot Size for Intensity-Modulated Proton Therapy Potentially Improves Salivary Gland-Sparing in Oropharyngeal Cancer

Fuel and Energy Abstracts

To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could... more To investigate whether intensity-modulated proton therapy with a reduced spot size (rsIMPT) could further reduce the parotid and submandibular gland dose compared with previously calculated IMPT plans with a larger spot size. In addition, it was investigated whether the obtained dose reductions would theoretically translate into a reduction of normal tissue complication probabilities (NTCPs). Ten patients with N0 oropharyngeal cancer were included in a comparative treatment planning study. Both IMPT plans delivered simultaneously 70 Gy to the boost planning target volume (PTV) and 54 Gy to the elective nodal PTV. IMPT and rsIMPT used identical three-field beam arrangements. In the IMPT plans, the parotid and submandibular salivary glands were spared as much as possible. rsIMPT plans used identical dose-volume objectives for the parotid glands as those used by the IMPT plans, whereas the objectives for the submandibular glands were tightened further. NTCPs were calculated for salivary dysfunction and xerostomia. Target coverage was similar for both IMPT techniques, whereas rsIMPT clearly improved target conformity. The mean doses in the parotid glands and submandibular glands were significantly lower for three-field rsIMPT (14.7 Gy and 46.9 Gy, respectively) than for three-field IMPT (16.8 Gy and 54.6 Gy, respectively). Hence, rsIMPT significantly reduced the NTCP of patient-rated xerostomia and parotid and contralateral submandibular salivary flow dysfunction (27%, 17%, and 43% respectively) compared with IMPT (39%, 20%, and 79%, respectively). In addition, mean dose values in the sublingual glands, the soft palate and oral cavity were also decreased. Obtained dose and NTCP reductions varied per patient. rsIMPT improved sparing of the salivary glands and reduced NTCP for xerostomia and parotid and submandibular salivary dysfunction, while maintaining similar target coverage results. It is expected that rsIMPT improves quality of life during and after radiotherapy treatment.