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836 poster The development of a decision model for clinical trials
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Conclusion: In view of lack of complete response, evidenced by planimetric and lab. Finding, other therapeutic protocols is highly recommended. 835 poster Method for measurement of fetal dose during head and neck radiotherapy in pregnant patients
D. van Kampen, B. De Ost, D. Van den Weyngaert AZ Middelheim, Radiotherapy, Antwerp, Belgium Although rarely indicated, radiotherapy of a pregnant patient occurs. Risk of radiation on the fetus must be taken into account. Therefore the fetal dose has to be measured and compared to the available data in the literature. A 27 year old pregnant (29 weeks gestational age) woman with a T4N1M0 tongue carcinoma was referred for postoperative radiotherapy. For this patient, standard treatment with two opposing lateral fields and a matching anterior supra clavicular field was used up to 50Gy with an additional boost up to 66Gy with lateral fields in daily 2 Gy fractions. To minimize scatter, 6MV was used for the treatment. The use of the motorized wedge and MLC was not considered a problem as the wedge and MLC are high inside the head for the Elekta Sli machine used. The actual treatment fields of a patient were transferred to the AIderson phantom. The treatment was simulated on the AIderson phantom from the head down to the diaphragm in succession fitted with a small water tank to simulate the abdomen. An ionization chamber was positioned in the center of the tank. The 'fetal' dose (ionization chamber) and the dose on the central axis of each field (in vivo diode measurements) were determined. To reference the results from the phantom study to the actual patients, we also measure with a diode detector on a fixed distance (25 cm) from the central axis of the anterior supra clavicular field towards the abdomen (fundus uteri) of both the phantom and the patient. This measurement is repeated every day during treatment. The data from the phantom measurements show an estimated 6 cGy to the fetus. The abdominal reference diode dose is confirmed by the in vivo reference measurements. In conclusion, the treatment of pregnant head and neck patients with radiotherapy is feasible if unavoidable. It is possible not to exceed the threshold dose of 100-200 mGy according to the ICRP-84 guidelines. 836 poster The development of a decision model for clinical trials
C.J.G. Dehing, L. Boersma, D. de Ruysscher, S. Wanders, P. Lambin Maastro clinic, radiation oncology, Heerlen, The Netherlands Introduction: There are many radiotherapy departments have personnel. Choices have to be largely based on subjective preferences of researcher's).
clinical trials available but limited time, money and made. These choices are grounds (e.g. personal
In order to make this decision with more objectivity we have developed a decision model. Material and method: The approach was taken to develop a modified version of the Boston Methodology which facilitates the ability to make choices. Potential benefit of a clinical trial is assessed using five criteria: 1) potential impact on survival or Ioco-regional control; 2) potential impact on the image of our discipline; 3) concordance with strategic choices/research lines; 4) potential impact on quality of life and 5) amount of papers expected. Probability of success is assessed also using five criteria: 1) financial resources for
implementation; 2) know-how availability within Maastroclinic; 3) existence of a sufficient patient population; 4) existence of competing trials and 5) percentage of asked patients that will decide to participate. The mean scores on probability of success and potential benefit are visualized on a graph. Potential benefit is shown at the x-axis, probability of success is on the y-axis. On both axes the maximum score is 100 points and a cut-off point of 50 is chosen. So all the new potential trials are classified into four categories: 1) the "losers": low probability of success and low potential benefit; 2) the "bread and butter": high probability of success and low potential benefit; 3) the "wild cards": tow probability of success and high potential benefit; 4) the "stars": high probability of success and high potential benefit. Results: In order to test the feasibility of the instrument a pilot study was performed. Four researchers assessed four different trials. The agreement between the rater's was sometimes low. The ICC's (intra-class correlations) for potential benefit and probability of success were respectively 0,60 and 0,75. The Pearson correlation ranged from 0,23 to 0,95 for potential benefit and from 0,75 to 0,93 for probability of success. Conclusions: According to the researchers the model was applicable in an easy way. The rather low agreement between raters reflects the real situation of decision making. Although everybody takes into account the same criteria, the expected outcome is still subjective. So variability in scoring can be large, but this should not be seen as a problem. The purpose of the model is not that it makes decisions for us, but using the model helps us to make well thought out decisions and makes the decision process more transparent. The mean score of a trial, visualized in the graph, can be discussed during research-meetings. It is a helpful tool to gain insight into possible reasons for participating in a clinical trial. 837 poster Distributed competence support of a Swedish proton therapy centre (SPTC)
A. Montelius ~, T. Bj(~rk-Eriksson2, M. Karlsson 3, O. Mattsson 2, P. Nilsson 4, B. Zackrisson 3 1University Hospital, Radiation Physics, Uppsala, Sweden 2Sahlgren University Hospital, Oncology/Radiation Physics, Gdteborg, Sweden 3University Hospital, Radiation Physics/Oncology, Ume& Sweden 4University Hospital, Radiation Physics, Lund, Sweden The purpose of this project was to develop methods for shared governance and distributed competence support of a national proton therapy centre. This facility will be supported by closely collaborating experts at the participating university departments which are geographically distributed across the country with well defined regional responsibilities. A national group of radiation oncotogists and medical physicists have made an in-depth investigation of this project resulting in a published report (in Swedish) in 2003. The report includes detailed data on the clinical gain, technology solutions and health economics. The report strongly indicates that a facility designed for a minimum of 1000 patients per year and up to 2000 patients per year is feasible. SPTC will be equipped with one proton accelerator and two full IMPT-gantries. All patient work-up and treatment preparation will be made locally at each participating university hospital.. The facility will be a pure production site for proton therapy and the treatment delivery will be performed according to detailed treatment prescriptions. The distributed expert support of this facility wilt be based on a common database for all treatment data, standardised and
$357
Conclusion: In view of lack of complete response, evidenced by planimetric and lab. Finding, other therapeutic protocols is highly recommended. 835 poster Method for measurement of fetal dose during head and neck radiotherapy in pregnant patients
D. van Kampen, B. De Ost, D. Van den Weyngaert AZ Middelheim, Radiotherapy, Antwerp, Belgium Although rarely indicated, radiotherapy of a pregnant patient occurs. Risk of radiation on the fetus must be taken into account. Therefore the fetal dose has to be measured and compared to the available data in the literature. A 27 year old pregnant (29 weeks gestational age) woman with a T4N1M0 tongue carcinoma was referred for postoperative radiotherapy. For this patient, standard treatment with two opposing lateral fields and a matching anterior supra clavicular field was used up to 50Gy with an additional boost up to 66Gy with lateral fields in daily 2 Gy fractions. To minimize scatter, 6MV was used for the treatment. The use of the motorized wedge and MLC was not considered a problem as the wedge and MLC are high inside the head for the Elekta Sli machine used. The actual treatment fields of a patient were transferred to the AIderson phantom. The treatment was simulated on the AIderson phantom from the head down to the diaphragm in succession fitted with a small water tank to simulate the abdomen. An ionization chamber was positioned in the center of the tank. The 'fetal' dose (ionization chamber) and the dose on the central axis of each field (in vivo diode measurements) were determined. To reference the results from the phantom study to the actual patients, we also measure with a diode detector on a fixed distance (25 cm) from the central axis of the anterior supra clavicular field towards the abdomen (fundus uteri) of both the phantom and the patient. This measurement is repeated every day during treatment. The data from the phantom measurements show an estimated 6 cGy to the fetus. The abdominal reference diode dose is confirmed by the in vivo reference measurements. In conclusion, the treatment of pregnant head and neck patients with radiotherapy is feasible if unavoidable. It is possible not to exceed the threshold dose of 100-200 mGy according to the ICRP-84 guidelines. 836 poster The development of a decision model for clinical trials
C.J.G. Dehing, L. Boersma, D. de Ruysscher, S. Wanders, P. Lambin Maastro clinic, radiation oncology, Heerlen, The Netherlands Introduction: There are many radiotherapy departments have personnel. Choices have to be largely based on subjective preferences of researcher's).
clinical trials available but limited time, money and made. These choices are grounds (e.g. personal
In order to make this decision with more objectivity we have developed a decision model. Material and method: The approach was taken to develop a modified version of the Boston Methodology which facilitates the ability to make choices. Potential benefit of a clinical trial is assessed using five criteria: 1) potential impact on survival or Ioco-regional control; 2) potential impact on the image of our discipline; 3) concordance with strategic choices/research lines; 4) potential impact on quality of life and 5) amount of papers expected. Probability of success is assessed also using five criteria: 1) financial resources for
implementation; 2) know-how availability within Maastroclinic; 3) existence of a sufficient patient population; 4) existence of competing trials and 5) percentage of asked patients that will decide to participate. The mean scores on probability of success and potential benefit are visualized on a graph. Potential benefit is shown at the x-axis, probability of success is on the y-axis. On both axes the maximum score is 100 points and a cut-off point of 50 is chosen. So all the new potential trials are classified into four categories: 1) the "losers": low probability of success and low potential benefit; 2) the "bread and butter": high probability of success and low potential benefit; 3) the "wild cards": tow probability of success and high potential benefit; 4) the "stars": high probability of success and high potential benefit. Results: In order to test the feasibility of the instrument a pilot study was performed. Four researchers assessed four different trials. The agreement between the rater's was sometimes low. The ICC's (intra-class correlations) for potential benefit and probability of success were respectively 0,60 and 0,75. The Pearson correlation ranged from 0,23 to 0,95 for potential benefit and from 0,75 to 0,93 for probability of success. Conclusions: According to the researchers the model was applicable in an easy way. The rather low agreement between raters reflects the real situation of decision making. Although everybody takes into account the same criteria, the expected outcome is still subjective. So variability in scoring can be large, but this should not be seen as a problem. The purpose of the model is not that it makes decisions for us, but using the model helps us to make well thought out decisions and makes the decision process more transparent. The mean score of a trial, visualized in the graph, can be discussed during research-meetings. It is a helpful tool to gain insight into possible reasons for participating in a clinical trial. 837 poster Distributed competence support of a Swedish proton therapy centre (SPTC)
A. Montelius ~, T. Bj(~rk-Eriksson2, M. Karlsson 3, O. Mattsson 2, P. Nilsson 4, B. Zackrisson 3 1University Hospital, Radiation Physics, Uppsala, Sweden 2Sahlgren University Hospital, Oncology/Radiation Physics, Gdteborg, Sweden 3University Hospital, Radiation Physics/Oncology, Ume& Sweden 4University Hospital, Radiation Physics, Lund, Sweden The purpose of this project was to develop methods for shared governance and distributed competence support of a national proton therapy centre. This facility will be supported by closely collaborating experts at the participating university departments which are geographically distributed across the country with well defined regional responsibilities. A national group of radiation oncotogists and medical physicists have made an in-depth investigation of this project resulting in a published report (in Swedish) in 2003. The report includes detailed data on the clinical gain, technology solutions and health economics. The report strongly indicates that a facility designed for a minimum of 1000 patients per year and up to 2000 patients per year is feasible. SPTC will be equipped with one proton accelerator and two full IMPT-gantries. All patient work-up and treatment preparation will be made locally at each participating university hospital.. The facility will be a pure production site for proton therapy and the treatment delivery will be performed according to detailed treatment prescriptions. The distributed expert support of this facility wilt be based on a common database for all treatment data, standardised and