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Comparison of Optically Stimulated Luminescence Detectors with Thermo Luminescence Detectors for In Vivo Dosimetry of Pediatric Total Body Irradiation Patients
I. J. Radiation Oncology d Biology d Physics
S664
Volume 81, Number 2, Supplement, 2011
and in circumstances that require rapid symptom relief. RT resulted in excellent local disease control and palliation of symptoms without significant toxicity. We recommend irradiating chloromas to at least 20 Gy, and propose 24 Gy in 12 fractions as an appropriate regimen. Given the limited experience in treatment chloromas, further study of combined modality therapy is warranted. Author Disclosure: R.L. Bakst: None. S. Wolden: None. J. Yahalom: None.
2948
Radio-induced Breast Cancers Display Aggressive Pathological Characteristics: A Retrospective Study by The French Pediatric Oncology Society (SFCE)
C. Demoor-Goldschmidt1, F. De Vathaire2, O. Oberlin3, G. Noel4, V. Brillaud5, V. Bernier6, A. Laprie7, L. Claude8, M. Mahe1, S. Supiot1 1 Institut de Cancerologie de l’Ouest, Saint Herblain, France, 2INSERM UMRS 1018, Villejuif, France, 3Institut Gustave Roussy, Villejuif, France, 4Centre Paul Strauss, Strasbourg, France, 5Institut Bergonie, Bordeaux, France, 6Centre Alexis Vautrin, Nancy, France, 7Institut Claudius Regaud, Toulouse, France, 8Centre Leon Berard, Lyon, France
Purpose/Objective(s): Thoracic radiotherapy given at a young age (\30y) in patients treated for cancer was shown to induce secondary breast cancers (SBC) with a cumulative incidence .12% at the age of 40 years. We analyzed the clinical and pathological characteristics of SBC patients treated in 6 cancer centers of the Survivorship Committee of SFCE. Materials/Methods: Clinical and pathological characteristics of women who developed an SBC under the age of 50, following irradiation at a dose . 5 Gy before the age of 30 for hematological malignancies or solid tumors were retrospectively analyzed. SBC tumor characteristics were compared with tumors occurring in BRCA1 and 2 mutated patients (group I and II), in young women with breast cancer (\35 y) (group III), and in patients with breast cancer without known risk factors (group IV). Results: Eighty-two SBC occurred at a median age of 36 [range 16 - 50] in 75 patients treated for a primary cancer (Hodgkin lymphoma: 59.1%; solid tumors 36.4%) at the age of 15 [1 - 30] with a median time interval between thoracic radiotherapy and SBC of 21 years [3 - 43]. For 4,5%, the radiotherapy was a Total Body Irradiation. These patients were compared with 54, 34, 198 and 4378 tumors in group I, II, II and IV respectively. The incidence of ductal carcinoma in situ was 9.4% in SBC patients similar to control groups. SBC displayed more aggressive features (pT3, SBRIII, Triple negative) than group IV, similarly to BRCA2 patients [table 1]. Conclusions: Radio-induced SBC display aggressive pathological features. The past history of irradiation and chemotherapy may have significant implications on the management of SBC and can limit the treatment options, in particular if additional radiation or doxorubicin-based chemotherapy is needed. This emphasizes the need for screening in this high-risk population of women treated with thoracic irradiation before the age of 30 to detect tumors at an earlier stage. Pathological characteristics of the infiltrating SBC in comparison to 4 groups
pT3 pT1a pN1 SBR III ER+ and PR+ HER2/neu + Triple negative
SBC
Group I
Group II
Group III
Group IV
Significant differences
14.1% 21.2% 33.8% 33.3% 64.5% 15.6% 25.0%
3.6% 7.1% 36.8% 71.4% 25.0% 12.5% 54.2%
13.3% 0.0% 66.7% 47.6% 50.0% 12.5% 25.0%
11.0% 23.3% 54.1% 30.5% 56.0% 36.6% 18.3%
6.1% 21.8% 37.6% 18.8% 65.8% 12.8% 10.6%
SBC vs IV SBC vs III SBC vs IV SBC vs III SBC vs IV
Author Disclosure: C. Demoor-Goldschmidt: None. F. de Vathaire: None. O. Oberlin: None. G. Noel: None. V.Brillaud: None. V. Bernier: None. A. Laprie: None. L. Claude: None. M. Mahe: None. S. Supiot: None.
2949
Comparison of Optically Stimulated Luminescence Detectors with Thermo Luminescence Detectors for In Vivo Dosimetry of Pediatric Total Body Irradiation Patients
P. Yuen, L. J. Brewster Mallalieu, R. Sharma North Shore LIJ Health System, New Hyde Park, NY Purpose/Objective(s): Since total body irradiation (TBI) often involves pediatric patients, in vivo dosimetry is vital to accurately verify delivered dose. This study was conducted to determine if replacing thermo luminescence detectors (TLD) with optically stimulated luminescence (OSL) detectors would provide more accurate dosimetric information, with the added benefit of easier and more rapid acquisition of verification results. Materials/Methods: Over a five year period, 41 pediatric patients were treated at our institution with TBI, using the opposed lateral beam technique. Patients received 13.5 Gy given in 9 fractions, at 2 fractions per day. Midline in vivo dosimetry was performed during the first fraction by positioning detectors at beam entrance and exit sides for several points: mid-head, neck, mediastinum, umbilicus, knee, and ankle. For the initial 21 patients, TLDs were used. These were supplied and read by an outside vendor. After validation by physics staff, OSL detectors were then used clinically for all patients, including 20 pediatric TBI patients. The OSL detectors were read in-house approximately 1 hour after treatment. When prescription and measured dose varied by ± 10%, OSL exposure was repeated. Results: A total of approximately 500 TLD and 250 OSL measurements were analyzed. The comparison showed that measurements with OSLs were consistently closer to the prescribed dose than the TLDs. There was also a decrease in the standard deviation for measurements with OSL detectors compared with TLDs.
Proceedings of the 53rd Annual ASTRO Meeting
S665
Conclusions: OSL detectors are an effective tool in monitoring the delivered dose accuracy in TBI treatments. The short turnaround time for readings and ease of use provides an additional advantage over TLDs. Delays in receiving TLD measurements prevented same day action on readings outside of tolerance. During the delay period, the patient could be further under- or overdosed, with a reduced number of fractions remaining for correction. With OSL detectors, the readings are obtained immediately; corrective actions are taken and re-evaluated at the next fraction. Our preliminary data show that OSLs provide improved accuracy and precision over TLDs. Use of OSLs can result in more accurate dose delivery for pediatric TBI patients through adaptive planning and delivery. Comparison of TLD and OSL Accuracy
Detector placement site
Average % error (TLD reading vs Rx dose)
Standard deviation (TLD vs Rx dose)
Average % error (OSL reading vs Rx dose)
Standard deviation (OSL vs Rx dose)
3.93 6.40 4.61 9.64 8.28 10.18
13.48 18.92 18.05 20.12 15.02 16.54
-2.63 2.99 0.94 4.86 3.80 3.26
5.32 15.37 11.10 12.72 11.42 9.57
mid head neck mediastinum umbilicus knee ankle
Author Disclosure: P. Yuen: None. L.J. Brewster Mallalieu: None. R. Sharma: None.
2950
Estimating Life Years Lost to Quantify the Potential Benefit for Pediatric Patients of Advanced Photon or Proton Radiotherapy
P. N. Brodin1,2, I. R. Vogelius1, M. V. Maraldo1, A. K. Berthelsen1,3, P. Munck af Rosensch€old1, M. C. Aznar1, I. Kristensen4, T. Bj€ ork-Eriksson4, P. Nilsson4, S. M. Bentzen1,5 1 Department of Radiation Oncology, Rigshospitalet, Copenhagen, Denmark, 2Niels Bohr Institute, Faculty of Science, Copenhagen University, Copenhagen, Denmark, 3Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, ane University Hospital and Lund University, Lund, Sweden, Copenhagen, Denmark, 4Department of Oncology, Sk 5 Departments of Human Oncology, Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, WI
Purpose/Objective(s): To estimate and compare the Life Years Lost (LYL) attributable to secondary cancer induction and adverse cardiac events (CE), for pediatric patients undergoing mediastinal/abdominal radiotherapy (RT). Estimation of LYL allows for a direct comparison of different long-term risks on a common scale. The aim is to assess the potential gain of advanced photon or proton RT for these patients. Materials/Methods: Large published clinical data sets were used to derive dose-response parameters to estimate the excess hazard ratio (hrexcess) of a complication. Combined with the age- and sex-specific hazard in the general population this yielded an excess hazard (hexcess) for a cancer survivor as a function of attained age. Each endpoint’s prognosis was then taken into account to estimate the attributable expected shortening of life expectancy (LE). Competing risks of death were accounted for using life tables of childhood cancer survivors. Integrating over all ages yielded the average LYL attributable to each complication. The LYL measure is sensitive to the associated mortality and the age dependency of late complications, it thus weights early occurring events higher as more life years are lost at younger ages. Treatment plans were generated with inversely-optimized arc therapy (AT) and spot-scanned intensity-modulated proton therapy (IMPT), for four pediatric patients with mediastinal/abdominal tumors. The LYL measure was applied to compare these plans to the delivered conventional plans. Results: Secondary lung and stomach cancers are shown to contribute most to the LYL, because these organs are near the target volumes and the corresponding cancers have a relatively bad prognosis. LYL attributable to CE were decreased with AT and IMPT due to a reduction in mean cardiac dose of 3.4 and 5.2 Gy respectively, compared to conventional RT. The LYL are probably underestimated since the assumption is made that the hrexcess of a non-irradiated cancer survivor is the same as for a person in the general population. Conclusions: The LYL measure allows objective comparison of risks between modalities or treatment plans. The large ranges in LYL estimates suggest that long-term risks depend strongly on where the primary tumor is situated in these patients. An expanded patient cohort is being planned to better assess the potential benefit of advanced RT for this patient group. Table 1: Estimated LYL (range)
Breast cancer Lung cancer Thyroid cancer Stomach cancer Heart failure Myocardial infarction Total
Conventional
AT
IMPT
0.16 (0.01 - 0.31) 0.39 (0.04 - 1.21) 0.02 (0.00 - 0.07) 0.35 (0.01 - 0.90) 0.11 (0.06 - 0.25) 0.26 (0.07 - 0.40) 1.28 (0.19 - 3.13)
0.14 (0.01 - 0.27) 0.39 (0.07 - 1.28) 0.01 (0.00 - 0.04) 0.33 (0.02 - 0.80) 0.07 (0.02 - 0.22) 0.13 (0.03 - 0.22) 1.06 (0.15 - 2.84)
0.07 (0.00 - 0.15) 0.32 (0.02 - 1.14) 0.01 (0.00 - 0.03) 0.25 (0.00 - 0.66) 0.05 (0.00 - 0.18) 0.06 (0.01 - 0.18) 0.76 (0.03 - 2.33)
Author Disclosure: P.N. Brodin: None. I.R. Vogelius: None. M.V. Maraldo: None. A.K. Berthelsen: None. P. Munck af Rosensch€ old: C. Other Research Support; Research agreement with Varian Medical Systems. M.C. Aznar: None. I. Kristensen: None. T. Bj€ ork-Eriksson: None. P. Nilsson: None. S.M. Bentzen: None.
S664
Volume 81, Number 2, Supplement, 2011
and in circumstances that require rapid symptom relief. RT resulted in excellent local disease control and palliation of symptoms without significant toxicity. We recommend irradiating chloromas to at least 20 Gy, and propose 24 Gy in 12 fractions as an appropriate regimen. Given the limited experience in treatment chloromas, further study of combined modality therapy is warranted. Author Disclosure: R.L. Bakst: None. S. Wolden: None. J. Yahalom: None.
2948
Radio-induced Breast Cancers Display Aggressive Pathological Characteristics: A Retrospective Study by The French Pediatric Oncology Society (SFCE)
C. Demoor-Goldschmidt1, F. De Vathaire2, O. Oberlin3, G. Noel4, V. Brillaud5, V. Bernier6, A. Laprie7, L. Claude8, M. Mahe1, S. Supiot1 1 Institut de Cancerologie de l’Ouest, Saint Herblain, France, 2INSERM UMRS 1018, Villejuif, France, 3Institut Gustave Roussy, Villejuif, France, 4Centre Paul Strauss, Strasbourg, France, 5Institut Bergonie, Bordeaux, France, 6Centre Alexis Vautrin, Nancy, France, 7Institut Claudius Regaud, Toulouse, France, 8Centre Leon Berard, Lyon, France
Purpose/Objective(s): Thoracic radiotherapy given at a young age (\30y) in patients treated for cancer was shown to induce secondary breast cancers (SBC) with a cumulative incidence .12% at the age of 40 years. We analyzed the clinical and pathological characteristics of SBC patients treated in 6 cancer centers of the Survivorship Committee of SFCE. Materials/Methods: Clinical and pathological characteristics of women who developed an SBC under the age of 50, following irradiation at a dose . 5 Gy before the age of 30 for hematological malignancies or solid tumors were retrospectively analyzed. SBC tumor characteristics were compared with tumors occurring in BRCA1 and 2 mutated patients (group I and II), in young women with breast cancer (\35 y) (group III), and in patients with breast cancer without known risk factors (group IV). Results: Eighty-two SBC occurred at a median age of 36 [range 16 - 50] in 75 patients treated for a primary cancer (Hodgkin lymphoma: 59.1%; solid tumors 36.4%) at the age of 15 [1 - 30] with a median time interval between thoracic radiotherapy and SBC of 21 years [3 - 43]. For 4,5%, the radiotherapy was a Total Body Irradiation. These patients were compared with 54, 34, 198 and 4378 tumors in group I, II, II and IV respectively. The incidence of ductal carcinoma in situ was 9.4% in SBC patients similar to control groups. SBC displayed more aggressive features (pT3, SBRIII, Triple negative) than group IV, similarly to BRCA2 patients [table 1]. Conclusions: Radio-induced SBC display aggressive pathological features. The past history of irradiation and chemotherapy may have significant implications on the management of SBC and can limit the treatment options, in particular if additional radiation or doxorubicin-based chemotherapy is needed. This emphasizes the need for screening in this high-risk population of women treated with thoracic irradiation before the age of 30 to detect tumors at an earlier stage. Pathological characteristics of the infiltrating SBC in comparison to 4 groups
pT3 pT1a pN1 SBR III ER+ and PR+ HER2/neu + Triple negative
SBC
Group I
Group II
Group III
Group IV
Significant differences
14.1% 21.2% 33.8% 33.3% 64.5% 15.6% 25.0%
3.6% 7.1% 36.8% 71.4% 25.0% 12.5% 54.2%
13.3% 0.0% 66.7% 47.6% 50.0% 12.5% 25.0%
11.0% 23.3% 54.1% 30.5% 56.0% 36.6% 18.3%
6.1% 21.8% 37.6% 18.8% 65.8% 12.8% 10.6%
SBC vs IV SBC vs III SBC vs IV SBC vs III SBC vs IV
Author Disclosure: C. Demoor-Goldschmidt: None. F. de Vathaire: None. O. Oberlin: None. G. Noel: None. V.Brillaud: None. V. Bernier: None. A. Laprie: None. L. Claude: None. M. Mahe: None. S. Supiot: None.
2949
Comparison of Optically Stimulated Luminescence Detectors with Thermo Luminescence Detectors for In Vivo Dosimetry of Pediatric Total Body Irradiation Patients
P. Yuen, L. J. Brewster Mallalieu, R. Sharma North Shore LIJ Health System, New Hyde Park, NY Purpose/Objective(s): Since total body irradiation (TBI) often involves pediatric patients, in vivo dosimetry is vital to accurately verify delivered dose. This study was conducted to determine if replacing thermo luminescence detectors (TLD) with optically stimulated luminescence (OSL) detectors would provide more accurate dosimetric information, with the added benefit of easier and more rapid acquisition of verification results. Materials/Methods: Over a five year period, 41 pediatric patients were treated at our institution with TBI, using the opposed lateral beam technique. Patients received 13.5 Gy given in 9 fractions, at 2 fractions per day. Midline in vivo dosimetry was performed during the first fraction by positioning detectors at beam entrance and exit sides for several points: mid-head, neck, mediastinum, umbilicus, knee, and ankle. For the initial 21 patients, TLDs were used. These were supplied and read by an outside vendor. After validation by physics staff, OSL detectors were then used clinically for all patients, including 20 pediatric TBI patients. The OSL detectors were read in-house approximately 1 hour after treatment. When prescription and measured dose varied by ± 10%, OSL exposure was repeated. Results: A total of approximately 500 TLD and 250 OSL measurements were analyzed. The comparison showed that measurements with OSLs were consistently closer to the prescribed dose than the TLDs. There was also a decrease in the standard deviation for measurements with OSL detectors compared with TLDs.
Proceedings of the 53rd Annual ASTRO Meeting
S665
Conclusions: OSL detectors are an effective tool in monitoring the delivered dose accuracy in TBI treatments. The short turnaround time for readings and ease of use provides an additional advantage over TLDs. Delays in receiving TLD measurements prevented same day action on readings outside of tolerance. During the delay period, the patient could be further under- or overdosed, with a reduced number of fractions remaining for correction. With OSL detectors, the readings are obtained immediately; corrective actions are taken and re-evaluated at the next fraction. Our preliminary data show that OSLs provide improved accuracy and precision over TLDs. Use of OSLs can result in more accurate dose delivery for pediatric TBI patients through adaptive planning and delivery. Comparison of TLD and OSL Accuracy
Detector placement site
Average % error (TLD reading vs Rx dose)
Standard deviation (TLD vs Rx dose)
Average % error (OSL reading vs Rx dose)
Standard deviation (OSL vs Rx dose)
3.93 6.40 4.61 9.64 8.28 10.18
13.48 18.92 18.05 20.12 15.02 16.54
-2.63 2.99 0.94 4.86 3.80 3.26
5.32 15.37 11.10 12.72 11.42 9.57
mid head neck mediastinum umbilicus knee ankle
Author Disclosure: P. Yuen: None. L.J. Brewster Mallalieu: None. R. Sharma: None.
2950
Estimating Life Years Lost to Quantify the Potential Benefit for Pediatric Patients of Advanced Photon or Proton Radiotherapy
P. N. Brodin1,2, I. R. Vogelius1, M. V. Maraldo1, A. K. Berthelsen1,3, P. Munck af Rosensch€old1, M. C. Aznar1, I. Kristensen4, T. Bj€ ork-Eriksson4, P. Nilsson4, S. M. Bentzen1,5 1 Department of Radiation Oncology, Rigshospitalet, Copenhagen, Denmark, 2Niels Bohr Institute, Faculty of Science, Copenhagen University, Copenhagen, Denmark, 3Department of Clinical Physiology and Nuclear Medicine, Rigshospitalet, ane University Hospital and Lund University, Lund, Sweden, Copenhagen, Denmark, 4Department of Oncology, Sk 5 Departments of Human Oncology, Biostatistics and Medical Informatics, University of Wisconsin School of Medicine and Public Health, Madison, WI
Purpose/Objective(s): To estimate and compare the Life Years Lost (LYL) attributable to secondary cancer induction and adverse cardiac events (CE), for pediatric patients undergoing mediastinal/abdominal radiotherapy (RT). Estimation of LYL allows for a direct comparison of different long-term risks on a common scale. The aim is to assess the potential gain of advanced photon or proton RT for these patients. Materials/Methods: Large published clinical data sets were used to derive dose-response parameters to estimate the excess hazard ratio (hrexcess) of a complication. Combined with the age- and sex-specific hazard in the general population this yielded an excess hazard (hexcess) for a cancer survivor as a function of attained age. Each endpoint’s prognosis was then taken into account to estimate the attributable expected shortening of life expectancy (LE). Competing risks of death were accounted for using life tables of childhood cancer survivors. Integrating over all ages yielded the average LYL attributable to each complication. The LYL measure is sensitive to the associated mortality and the age dependency of late complications, it thus weights early occurring events higher as more life years are lost at younger ages. Treatment plans were generated with inversely-optimized arc therapy (AT) and spot-scanned intensity-modulated proton therapy (IMPT), for four pediatric patients with mediastinal/abdominal tumors. The LYL measure was applied to compare these plans to the delivered conventional plans. Results: Secondary lung and stomach cancers are shown to contribute most to the LYL, because these organs are near the target volumes and the corresponding cancers have a relatively bad prognosis. LYL attributable to CE were decreased with AT and IMPT due to a reduction in mean cardiac dose of 3.4 and 5.2 Gy respectively, compared to conventional RT. The LYL are probably underestimated since the assumption is made that the hrexcess of a non-irradiated cancer survivor is the same as for a person in the general population. Conclusions: The LYL measure allows objective comparison of risks between modalities or treatment plans. The large ranges in LYL estimates suggest that long-term risks depend strongly on where the primary tumor is situated in these patients. An expanded patient cohort is being planned to better assess the potential benefit of advanced RT for this patient group. Table 1: Estimated LYL (range)
Breast cancer Lung cancer Thyroid cancer Stomach cancer Heart failure Myocardial infarction Total
Conventional
AT
IMPT
0.16 (0.01 - 0.31) 0.39 (0.04 - 1.21) 0.02 (0.00 - 0.07) 0.35 (0.01 - 0.90) 0.11 (0.06 - 0.25) 0.26 (0.07 - 0.40) 1.28 (0.19 - 3.13)
0.14 (0.01 - 0.27) 0.39 (0.07 - 1.28) 0.01 (0.00 - 0.04) 0.33 (0.02 - 0.80) 0.07 (0.02 - 0.22) 0.13 (0.03 - 0.22) 1.06 (0.15 - 2.84)
0.07 (0.00 - 0.15) 0.32 (0.02 - 1.14) 0.01 (0.00 - 0.03) 0.25 (0.00 - 0.66) 0.05 (0.00 - 0.18) 0.06 (0.01 - 0.18) 0.76 (0.03 - 2.33)
Author Disclosure: P.N. Brodin: None. I.R. Vogelius: None. M.V. Maraldo: None. A.K. Berthelsen: None. P. Munck af Rosensch€ old: C. Other Research Support; Research agreement with Varian Medical Systems. M.C. Aznar: None. I. Kristensen: None. T. Bj€ ork-Eriksson: None. P. Nilsson: None. S.M. Bentzen: None.