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BENEFIT OF A CLINICAL DATA WAREHOUSE FOR DATA-COLLECTION IN RADIOTHERAPY
D OSE VOLUME PARAMETERS AND OUTCOME STUDIES
S 153
depending on treatment site different anatomic regions of the Alderson phantom were used. Dosimetric measurements were performed in the solid water phantom using TLD700 rods, EBT-films and a Farmer type ionisation chamber (IC), which were positioned along the gantry rotation axis at various distances from the field edge. Results: In general, peripheral doses were smaller for plans using unflattened beams. At 20 cm distance from the field edge TLD measurements reveal an average reduction of out-of-field dose for IMRT plans of 13±3% for the 10 MV prostate case and 15±3% for the 10 MV H&N case. For SBRT plans the reduction was 22±3% for 6 MV and 29±3% for 10 MV. Relative reductions of peripheral doses measured with EBT-films and IC agreed within 5%. In the examined range from 5.5 to 20 cm distance from the field edge unflattened beams showed a steeper dose fall off compared to flattened beams. A comparison of doses measured with TLDs and EBT-films showed on average a 9% over-response of TLDs. This deviation can be explained by the increased sensitivity of TLDs to photons of substantially lower energies compared to the calibration energy, which was 6 MV. Conclusions: Removing the flattening filter leads to reduced peripheral doses for advanced treatment techniques. Increasing nominal beam energy from 6 to 10 MV contributed to a further reduction in peripheral dose.
Dose Volume parameters and outcome studies 409 poster (Physics Track) ANALYSIS OF ACOUSTIC NEUROMAS RESPONSE AND COCHLEAR COMPLICATIONS AFTER TREATMENT WITH GAMMA KNIFE E. Koutsouveli1 , P. Mavroidis2 , P. Karaiskos4 , P. Sandilos5 , C. Stergiou1 , B. Andisheh2 , N. Papanikolaou6 , B. Lind2 , M. Torrens1 1 H YGEIA G ENERAL H OSPITAL, Department of Radiosurgery and Medical Physics, Marousi (Athens), Greece 2 K AROLINSKA I NSTITUTET AND S TOCKHOLM U NIVERSITY, Department of Medical Radiation Physics, Stockholm, Sweden 3 L ARISSA U NIVERSITY H OSPITAL, Department of Medical Physics, Larissa, Greece 4 M EDICAL S CHOOL , U NIVERSITY OF ATHENS, Department of Medical Physics, Athens, Greece 5 A RETEION U NIVERSITY H OSPITAL, Department of Radiology, Athens, Greece 6 U NIVERSITY OF T EXAS H EALTH S CIENCE C ENTER, Department of Radiological Sciences, San Antonio, TX, USA 7 R AY C LINIC C ANCER C ENTER AB, Stockholm, Sweden
Purpose: In this study, different dosimetric measures are associated with treatment outcome parameters which are derived from the clinical follow-up results. The purpose is to examine factors that are related with the response of acoustic neuromas and cochlear complications manifested after Gamma Knife radiosurgery. Materials: 63 patients, who were treated for acoustic neuromas are examined. The dose distributions delivered to the target and cochlea as well as the corresponding treatment outcomes, were available for each patient. CT and MRI images were acquired with the stereotactic frame in position. These images were used in the development of the treatment plans, which was performed using the dedicated GammaPlan treatment planning system. In this study, the Leksell Gamma Knife (model C) unit, which is equipped with an automated positioning system (APS), was used. For each examined tissue, two patient subgroups were formed: the response and control groups. All the patients had at least 2 years of follow-up. Clinical and radiological findings were used to assess target response, which is expressed as a size reduction of the target volume measured by GammaPlan (response group). Similarly, acouograms were used to assess the response of cochlea, which is expressed as any deterioration of hearing ability. Results: Comparing the response and non-response groups, the prescribed doses range between 11-14 Gy with a mean reference isodose of 46% against 11-12 Gy with a reference isodose of 51%, respectively. For the two groups of patients the average mean and minimum doses are 16.6 and 8.2 Gy against 16.2 and 8.4 Gy, respectively. Finally, the corresponding average conformity indices were 0.8 and 0.7. It is shown that for mean target doses larger than 15.0 Gy there is significant increase in the control rate. Regarding the cochlea, the change of the hearing level at 2 kHz and 4 kHz was 13.6 dB and 9.4 dB in the response group, whereas in the non-response group the change at these frequencies was -14.8 dB and -12.5 dB. For the two groups of patients the average mean and maximum doses are 3.8 Gy and 7.2 Gy against 3.8 Gy and 6.9 Gy, respectively. It is shown that for mean doses larger than 3.0 Gy there is a considerable deterioration of the hearing ability of cochlea.
Conclusions: It is found that when acoustic neuromas receive mean doses larger than 15.0 Gy, the control rate increases significantly. Similarly, a considerable increase in the cochlear complication rate is found for mean doses larger than 3.0 Gy. 410 poster (Physics Track) BENEFIT OF A CLINICAL DATA WAREHOUSE FOR DATACOLLECTION IN RADIOTHERAPY L. Persoon1 , S. Nijsten1 , C. Overhof1 , R. Debougnoux-Huppertz1 , D. De Ruysscher1 , P. Lambin1 , A. Dekker1 1 D EPARTMENT OF R ADIATION O NCOLOGY (MAASTRO), GROW – S CHOOL FOR O NCOLOGY AND D EVELOPMENTAL B IOLOGY, M AASTRICHT U NIVERSITY M EDICAL C ENTRE , M AASTRICHT, T HE N ETHERLANDS, Maastricht, Netherlands
Purpose: Collecting data in a medical environment is at present mostly performed manually and is therefore time-consuming and prone to errors. Faster and more accurate methods are needed to improve the data quality and to shorten data collection times because information is scattered over multiple data sources. The purpose of this study is to investigate the benefit of using modern data warehouse technology for data collection compared to the standard manual collection. Materials: In this study, a Computer Aided Theragnostics (CAT) data warehouse (Siemens IKM, Malvern, PA, USA) combined with automated tools for extraction of features from imaging and RT modalities (e.g. 3D dose matrices) was benchmarked against the currently used manual data-collection processes. For this study, two sets of variables were compiled for non-small cell lung cancer (NSCLC) and rectal cancer, using 27 patients per disease. The sets consisted of clinical variables like tumor staging, pathology results, DVH parameters (e.g. mean lung dose, V40 bladder), imaging features like FDG-PET-uptake (e.g. SUVmax, SUVmean) and treatment variables (e.g. overall treatment time and delivered dose). Both collection times and data inconsistencies between the manual collection and automated extraction were determined for both cases. Results are expressed as mean±1 standard deviation (SD). The Wilcoxon’s signed rank test was used. Results: The average time to collect the NSCLC data by manual extraction was 10.7±2.2 min per case and for the automated extraction 4.8±0.7 min per case (p<0.001). For rectal cancer, these times were 8.8±1.0 min and 4.8±0.9 min per case, respectively (p<0.05). In 3.2% of data collected for NSCLC and in 6.8% of data collected for rectal cancer, there was a discrepancy between variable values found with the manual and automated extraction. For both the NSCLC and rectal cancer data, 13 variables per patient were used to measure discrepancies between both methods. Conclusions: Aggregating data sources in a data warehouse is beneficial for data quality. Data can be collected faster and more reliable. These types of systems can be used retrospectively for the development of predictive models and prospectively for trial patient selection and automated population of electronic case report forms.
S 153
depending on treatment site different anatomic regions of the Alderson phantom were used. Dosimetric measurements were performed in the solid water phantom using TLD700 rods, EBT-films and a Farmer type ionisation chamber (IC), which were positioned along the gantry rotation axis at various distances from the field edge. Results: In general, peripheral doses were smaller for plans using unflattened beams. At 20 cm distance from the field edge TLD measurements reveal an average reduction of out-of-field dose for IMRT plans of 13±3% for the 10 MV prostate case and 15±3% for the 10 MV H&N case. For SBRT plans the reduction was 22±3% for 6 MV and 29±3% for 10 MV. Relative reductions of peripheral doses measured with EBT-films and IC agreed within 5%. In the examined range from 5.5 to 20 cm distance from the field edge unflattened beams showed a steeper dose fall off compared to flattened beams. A comparison of doses measured with TLDs and EBT-films showed on average a 9% over-response of TLDs. This deviation can be explained by the increased sensitivity of TLDs to photons of substantially lower energies compared to the calibration energy, which was 6 MV. Conclusions: Removing the flattening filter leads to reduced peripheral doses for advanced treatment techniques. Increasing nominal beam energy from 6 to 10 MV contributed to a further reduction in peripheral dose.
Dose Volume parameters and outcome studies 409 poster (Physics Track) ANALYSIS OF ACOUSTIC NEUROMAS RESPONSE AND COCHLEAR COMPLICATIONS AFTER TREATMENT WITH GAMMA KNIFE E. Koutsouveli1 , P. Mavroidis2 , P. Karaiskos4 , P. Sandilos5 , C. Stergiou1 , B. Andisheh2 , N. Papanikolaou6 , B. Lind2 , M. Torrens1 1 H YGEIA G ENERAL H OSPITAL, Department of Radiosurgery and Medical Physics, Marousi (Athens), Greece 2 K AROLINSKA I NSTITUTET AND S TOCKHOLM U NIVERSITY, Department of Medical Radiation Physics, Stockholm, Sweden 3 L ARISSA U NIVERSITY H OSPITAL, Department of Medical Physics, Larissa, Greece 4 M EDICAL S CHOOL , U NIVERSITY OF ATHENS, Department of Medical Physics, Athens, Greece 5 A RETEION U NIVERSITY H OSPITAL, Department of Radiology, Athens, Greece 6 U NIVERSITY OF T EXAS H EALTH S CIENCE C ENTER, Department of Radiological Sciences, San Antonio, TX, USA 7 R AY C LINIC C ANCER C ENTER AB, Stockholm, Sweden
Purpose: In this study, different dosimetric measures are associated with treatment outcome parameters which are derived from the clinical follow-up results. The purpose is to examine factors that are related with the response of acoustic neuromas and cochlear complications manifested after Gamma Knife radiosurgery. Materials: 63 patients, who were treated for acoustic neuromas are examined. The dose distributions delivered to the target and cochlea as well as the corresponding treatment outcomes, were available for each patient. CT and MRI images were acquired with the stereotactic frame in position. These images were used in the development of the treatment plans, which was performed using the dedicated GammaPlan treatment planning system. In this study, the Leksell Gamma Knife (model C) unit, which is equipped with an automated positioning system (APS), was used. For each examined tissue, two patient subgroups were formed: the response and control groups. All the patients had at least 2 years of follow-up. Clinical and radiological findings were used to assess target response, which is expressed as a size reduction of the target volume measured by GammaPlan (response group). Similarly, acouograms were used to assess the response of cochlea, which is expressed as any deterioration of hearing ability. Results: Comparing the response and non-response groups, the prescribed doses range between 11-14 Gy with a mean reference isodose of 46% against 11-12 Gy with a reference isodose of 51%, respectively. For the two groups of patients the average mean and minimum doses are 16.6 and 8.2 Gy against 16.2 and 8.4 Gy, respectively. Finally, the corresponding average conformity indices were 0.8 and 0.7. It is shown that for mean target doses larger than 15.0 Gy there is significant increase in the control rate. Regarding the cochlea, the change of the hearing level at 2 kHz and 4 kHz was 13.6 dB and 9.4 dB in the response group, whereas in the non-response group the change at these frequencies was -14.8 dB and -12.5 dB. For the two groups of patients the average mean and maximum doses are 3.8 Gy and 7.2 Gy against 3.8 Gy and 6.9 Gy, respectively. It is shown that for mean doses larger than 3.0 Gy there is a considerable deterioration of the hearing ability of cochlea.
Conclusions: It is found that when acoustic neuromas receive mean doses larger than 15.0 Gy, the control rate increases significantly. Similarly, a considerable increase in the cochlear complication rate is found for mean doses larger than 3.0 Gy. 410 poster (Physics Track) BENEFIT OF A CLINICAL DATA WAREHOUSE FOR DATACOLLECTION IN RADIOTHERAPY L. Persoon1 , S. Nijsten1 , C. Overhof1 , R. Debougnoux-Huppertz1 , D. De Ruysscher1 , P. Lambin1 , A. Dekker1 1 D EPARTMENT OF R ADIATION O NCOLOGY (MAASTRO), GROW – S CHOOL FOR O NCOLOGY AND D EVELOPMENTAL B IOLOGY, M AASTRICHT U NIVERSITY M EDICAL C ENTRE , M AASTRICHT, T HE N ETHERLANDS, Maastricht, Netherlands
Purpose: Collecting data in a medical environment is at present mostly performed manually and is therefore time-consuming and prone to errors. Faster and more accurate methods are needed to improve the data quality and to shorten data collection times because information is scattered over multiple data sources. The purpose of this study is to investigate the benefit of using modern data warehouse technology for data collection compared to the standard manual collection. Materials: In this study, a Computer Aided Theragnostics (CAT) data warehouse (Siemens IKM, Malvern, PA, USA) combined with automated tools for extraction of features from imaging and RT modalities (e.g. 3D dose matrices) was benchmarked against the currently used manual data-collection processes. For this study, two sets of variables were compiled for non-small cell lung cancer (NSCLC) and rectal cancer, using 27 patients per disease. The sets consisted of clinical variables like tumor staging, pathology results, DVH parameters (e.g. mean lung dose, V40 bladder), imaging features like FDG-PET-uptake (e.g. SUVmax, SUVmean) and treatment variables (e.g. overall treatment time and delivered dose). Both collection times and data inconsistencies between the manual collection and automated extraction were determined for both cases. Results are expressed as mean±1 standard deviation (SD). The Wilcoxon’s signed rank test was used. Results: The average time to collect the NSCLC data by manual extraction was 10.7±2.2 min per case and for the automated extraction 4.8±0.7 min per case (p<0.001). For rectal cancer, these times were 8.8±1.0 min and 4.8±0.9 min per case, respectively (p<0.05). In 3.2% of data collected for NSCLC and in 6.8% of data collected for rectal cancer, there was a discrepancy between variable values found with the manual and automated extraction. For both the NSCLC and rectal cancer data, 13 variables per patient were used to measure discrepancies between both methods. Conclusions: Aggregating data sources in a data warehouse is beneficial for data quality. Data can be collected faster and more reliable. These types of systems can be used retrospectively for the development of predictive models and prospectively for trial patient selection and automated population of electronic case report forms.