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Radiometabolic therapy with 131I for hyperthyroidism from Graves' disease. First experiences in Sassari Hospital
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Abstracts/Physica Medica 32 (2016) e97–e115
C.373 A STUDY OF MYOCARDIAL TOMOSCINTIGRAPHY BY SEMI-QUANTITATIVE ANALYSIS L. Pagan *,a, E. Cason b, S. Zoboli b, G. Fierro a, G. Lucchi b, R. Soavi a, P. Berardi a. a Fisica Sanitaria, Azienda USL, Bologna, Italy; b Medicina Nucleare, Azienda USL, Bologna, Italy Introduction: In order to verify the possible sensitivity variation using semiquantitative analysis, a comparison was performed between myocardial tomoscintigraphy of a phantom under different setup and equipment, along with a clinical cases review. Materials and Methods: Acquisitions were carried out with heart insert ECT/CAR/I, positioned inside the cylindrical phantom ‘Standard-Jaszczak’ and equipped by two warm sectors (one with 50% of phantom activity concentration, the other with 20%). Scans were performed both by a dedicated gamma camera (CardioMD – Philips) under different setup (i.e. by different distances between detectors and phantom), and by a General Purpose gamma camera (Infinia – GE). Images were processed using the Filtered Back Projection (FBP) algorithm and, when possible, the iterative one (Astonish – Philips). Then, comparisons between different acquisitions were performed using the regional perfusion semi-quantitative analysis with polar maps. Finally, a patient’s case review was carried out. Results: In all FBP images the 50% insert involved 3 segments of maps, including 2 identified as pathological, while the 20% one has involved 5 of which only 3 are pathological. In CardioMD images reconstructed with Astonish, the 50% insert involved 2 segments of maps, both pathological, while the 20% one has involved 4, all reported as pathological. Positive patients’ review also showed higher scores when iterative reconstruction was used, while in negative patients there were no differences. Conclusions: Semi-quantitative analysis with polar maps showed that there are no significant differences between the images acquired with different setup and equipment, when reconstructed by FBP. The use of the Astonish iterative algorithm instead has highlighted, compared to FBP, greater sensitivity both in phantom and in patients. http://dx.doi.org/10.1016/j.ejmp.2016.01.379
C.374 STUDY OF WHOLE BODY RESIDENCE TIMES FOR 131I TREATMENT OF THYROID CANCER M. Paoli *, E. Di Nicola, P. D’Avenia, M. Camarda, L. Montani, G. Rossi, S. Fattori. ASUR Marche, Macerata, Italy Introduction: The existence of a rare and precious archive, which contains measures of whole body counts for 1156 patients affected from thyroid carcinoma and subjected to ablation therapy with 131I, was the start for this study which aims to establish a reference standard for the residence times of 131I for patients hospitalized in nuclear medicine department. Materials and Methods: The method is based on the measures of total body counts, made by Geiger–Müller counters present in protected patient rooms, after administration of therapeutic activity of 131I in order to ablate the thyroid remnant. Patients were divided into two groups: 869 at first treatment with 131I and 287 treated with 131I for persistent disease after first treatment; for each of them the measures of total body counts have been normalized with the first measure and then it was calculated the residence time in the whole body through a bi-exponential fit of the counts/time curve. The concept of residence time is expressed in units of time but it is the number of nuclear transitions that occur in a certain region in a time interval normalized to the activity administered (Bq-s/Bq or μCi-h/μCi). Results: The results obtained for residence times are: First treatment: mean [h] 15.89, standard deviation 5.87, IC at 95% [15.50;16.28]; nth treatment: mean [h] 19.07, standard deviation 6.45, IC at 95% [18.33;19.82]. Conclusions: The efficacy of the nuclear medicine therapy is connected to the absorbed dose by the target that strongly depends on the time in which the radioiodine remains inside the tumor cell.
From the results it is evident that the mechanism of wash-out of the radioiodine I in whole body is slower for patients reprocessed. The high abundance of patients made it possible to calculate precise estimates of the confidence level of residence time’s average value; also the two intervals are quite distinct as thus also the two statistical populations. http://dx.doi.org/10.1016/j.ejmp.2016.01.380
C.375 RETROSPECTIVE ANALYSIS OF DOSE–RESPONSE FOR HCC LESIONS TREATED WITH 90Y RESIN MICROSPHERES C. Pettinato *,a, C. Mosconi b, A. Cappelli b, S. Civollani a, P. Pini c, F. Monari d, B. Angelelli e, E. Nobili e, S. Fanti f, R. Golfieri b. a U.O. Fisica Sanitaria, AOU S.Orsola Malpighi, Bologna, Italy; b U.O. Radiologia, AOU S.Orsola Malpighi, Bologna, Italy; c U.O. Medicina Interna, AOU S.Orsola Malpighi, Bologna, Italy; d U.O. Radioterapia, AOU S.Orsola Malpighi, Bologna, Italy; e U.O. Oncologia, AOU S.Orsola Malpighi, Bologna, Italy; f U.O. Medicina Nucleare, AOU S.Orsola Malpighi, Bologna, Italy Aim: The aim of this study was to evaluate the correlation between tumor dose and local tumor response. Materials and Methods: From September 2010 to October 2014, 48 patients affected by HCC have been treated with 90Y resin microspheres. All pts received an intra-hepatic infusion of 150 MBq of 99mTc-MAA to calculate lung and extra-hepatic shunts and to perform lesion and whole liver dosimetry using the MIRD formalism. The activity to be injected was calculated using the BSA formula and was modulated based on tumor and normal liver doses, limiting the dose to whole normal liver to about 30 Gy. Results: The mean injected 90Y activity was 1.5 (r: 0.4–2.4 GBq). The mean tumor volume was 286 cc (range: 43 cc–2566 cc), while the average dose was 258 Gy (range: 13–858 Gy). Tumors with smaller volumes received higher doses. The average doses to tumors with volumes below 100 cc, between 100 and 200 cc, between 200 and 500 cc and above 500 cc were respectively 436 Gy (95% IC: 267.6–603.5 Gy), 263 Gy (95% IC: 195.6– 329.4 Gy), 207.8 Gy (95% IC: 157.8–257.8 Gy) and 56.2 Gy (95% IC: 27.1– 85.3 Gy). 25/48 pts received an average tumor dose greater than 200 Gy. 9/25 pts showed a complete response and an average survival >12 months. 9/25 pts had a good response, while 7/25 pts had a stable response on the treated lesion but a worsening of the disease due to progression of nontreated lesions. 3/23 pts, who received less than 200 Gy, had a complete response of the treated lesion, 14/23 had a good response and 6 had stable disease. Our results suggest that big tumors (>300 cc) are responsive to lower average doses. Conclusions: Average tumor dose based on 99mTc-MAA SPECT images is a good prognostic value to predict tumor response to 90Y resin microsphere treatments in patients affected by HCC. Our results showed that 36% of tumors that received more than 200 Gy had complete response while 64% of tumors had stable or good response for more than one year. http://dx.doi.org/10.1016/j.ejmp.2016.01.381
C.376 RADIOMETABOLIC THERAPY WITH 131I FOR HYPERTHYROIDISM FROM GRAVES’ DISEASE. FIRST EXPERIENCES IN SASSARI HOSPITAL F. Pinna *,a, R. Bona a,b, C. Marchioni a,b, A. Poggiu a,b, M. Tamponi a,b, A. Spanu a, P.G. Marini a,b. a Azienda Ospedaliero Universitaria, Sassari, Italy; b Azienda Sanitaria Locale n° 1, Sassari, Italy Introduction: In our center we are treating patients with Graves’s disease with 131I for 2 years. The administered activity is customized by determining the parameters related to the kinetics of radiopharmaceutical uptake by a nonlinear mixedeffects model and effective thyroid volumes by echography. To emphasize the importance of this choice, we analyzed the dependence of the administered 131I activity by the calculation method. Materials and Methods: The method used allows to determine kinetic parameters (maximum uptake Umax and time effective half-life T1/2eff) fitting thyroid uptake measurements at 4, 24 and 72 hours from administration of 1,5 MBq of 131I, through a University of Massachusetts tool, which makes use of an algorithm based on results of reference [1].
Abstracts/Physica Medica 32 (2016) e97–e115
We assessed whether this method actually leads to significant differences in the evaluation of the activity to be administered than the simplified methods reported in the AIMN-AIFM guidelines, which provide the evaluation of T1/2eff from linear fit of the uptake at 24 and 72 h (or longer), and in the ICRP 53, which considers a standard 132 hours T1/2eff. In both of these simplified methods Umax is considered at 24th hour. The results are concerned with the first 7 patients (administered activities range from 102 to 303 MBq). Results: The results show that both simplified methods can give quite different results in the assessment of activity to be administered (maximum overestimation >40% and maximum underestimation close to 40%) if compared to the tool. Conclusions: The use of simplified methods can lead to an incorrect assessment of the activity to be administered and it should therefore be limited to special cases. Reference [1] Merrill S, Horowitz J, Traino AC, Chipkin SR, Hollot CV, Chait Y. Accuracy and optimal timing of activity measurements in estimating the absorbed dose of radioiodine in the treatment of Graves’ disease. Phys Med Biol 2011;56:557–71. http://dx.doi.org/10.1016/j.ejmp.2016.01.382
C.377 USE OF CUMULATIVE SUV VOLUME HISTOGRAM AS A NEW TOOL TO RADIOTHERAPY TREATMENT MONITORING P. Pisciotta *,a,b, A. Stefano a,c, G. Russo a,d, M.G. Sabini d, L.M. Valastro d, T. Licciardello d , C. D’Arrigo d , F. Marletta d , D. D’Urso a,b , G. Borasi a , M. Ippolito d, M.G. Gilardi a. a Istituto di Bioimmagini e Fisiologia Molecolare, Consiglio Nazionale delle Ricerche (IBFM CNR), Cefalù (PA), Italy; b Università degli Studi di Catania, Catania, Italy; c Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica (DICGIM), Università degli Studi di Palermo, Palermo, Italy; d Azienda Ospedaliera per l’Emergenza Cannizzaro, Catania, Italy Introduction: This study investigated the biological evolution of tumor volume using [11C]-Methionine-PET (MET-PET) images. MET-PET diagnostic exams provide metabolic information about brain lesions impossible to obtain using other imaging techniques. Similar to the radiotherapy Dose– Volume Histogram (DVH), the Cumulative SUV–volume Histogram (CSH) represents the percentage of tumor metabolic volume higher than an SUV threshold, variable from 0 to the maximum SUV value. The aim of this study was to evaluate how the CSH could be used as a tool for the treatment monitoring in stereotactic radiosurgery. Materials and Methods: The patients selected for this study presented one or more brain metastases. The lesions were studied using metabolic METPET imaging before and after 3 months of the Gamma Knife treatment. The Radiotracer distribution changes were evaluated using the CSH parameters, that is: Area under the CSH, Uptake Intensity, etc. The CSH parameters were calculated for 14 patients using a homemade MATLAB tool. Results: According to the literature, the area under the CSH curve was considered as a quantitative index of the heterogeneity in the MET uptake inside the lesion volume. The percentage change of CSH was obtained as follows: δCSH(post vs pre) = 100*(CSHpost − CSHpre)/CSHpre, and this value was compared with the Nuclear Medicine physicians qualitative assessment. These CSH variations were in agreement with qualitative observation of METPET/CT images. Conclusions: The CSH could be a new tool to monitor the treatment followup for stereotactic radiosurgery. The CSH parameters seem to be correlated with the tumor response and permit a more accurate early assessing of therapy response. Future studies are needed to evaluate the threshold of the CSH parameter changes to discriminate between responders and non-responders. http://dx.doi.org/10.1016/j.ejmp.2016.01.383
C.378 NEW PROMISING SCINTILLATION CRYSTALS FOR MOLECULAR IMAGING APPLICATIONS: CRY018 AND CRY019 C. Polito *,a, M.N. Cinti b,c, R. Pellegrini b,c, R. Pani c,d. a SAIMLAL Department, Sapienza University of Rome, Rome, Italy; b Department of Molecular Medicine,
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Sapienza University of Rome, Rome, Italy; c INFN Roma I Section, Rome, Italy; d Department of Sciences and Medical and Surgical Biotechnologies, Sapienza University of Rome, Rome, Italy Introduction: A detailed investigation of new scintillation crystals, produced by CRYTUR spol. s r.o. (Czech Republic), is presented. Pulse height distributions have been measured as a function of photon energy, in order to evaluate the Energy Resolution. The crystals have shown promising performances for gamma ray imaging applications as the short scintillation decay time that makes these scintillation crystals attractive for the improvement of a wide range of applications in Nuclear Medicine, like PET and SPECT instrumentations. Materials and Methods: A couple of new mixed rare-earth silicate single crystal scintillation materials (CRY018 and CRY019) have been studied. The crystals have round shape and white painting on all sides, except on the one in contact with Photomultiplier Tubes. Their size is proper of a small Field of View gamma imager (50 mm diameter and 6 mm thickness). The crystals were irradiated with radioactive source with different photon energy in order to characterize their Energy Resolution. Subsequently the Spatial Linearity and Spatial Resolution were quantified with a scanning of the crystals surface with a 1 mm Tc99m point source. The fast decay time allows combining the crystals with fast timing applications (i.e. Silicon Photomultiplier). Results: The Energy Resolution is close to 16.3% for CRY019 and 12.4% for CRY018 at 122 keV (comparable with one of NaI:Tl that is 12%). About spatial linearity, the CRY019 crystal shows the worse linearity but the greater efficiency respect to the CRY018. Finally, the intrinsic spatial resolutions were 1.6 mm and 2 mm for CRY018 and CRY019 respectively. Conclusion: The satisfactory results in terms of Energy and Spatial Resolution suggest the employment of these crystals in many different applications. Moreover these materials are not hygroscopic, this means that they do not need to be contained in a sealed casing. Finally, all these great performances make the crystals attractive also for dual modality applications. http://dx.doi.org/10.1016/j.ejmp.2016.01.384
C.379 RED MARROW AND BLOOD DOSIMETRY IN 131I TREATMENT OF METASTATIC DIFFERENTIATED THYROID CARCINOMA: 7 YEARS EXPERIENCE AT MAURIZIANO HOSPITAL OF TURIN E. Richetta * ,a , C. Cutaia a , S. Valzano a , M. Pasquino a , G. Lo Moro a , G. Brusasco b, R.E. Pellerito b, M. Stasi a. a S.C. Fisica Sanitaria, AO Ordine Mauriziano di Torino, Torino, Italy; b S.C. Medicina Nucleare, AO Ordine Mauriziano di Torino, Torino, Italy Introduction: Radioiodine treatment of metastatic differentiated thyroid cancer is limited by red marrow toxicity. In our institution dosimetry to red marrow and blood is performed before and after therapy to individually determine the maximum tolerable 131I activity. The study shows the results obtained comparing different dosimetric methods, pre- and intherapy dosimetry and doses to patients with repeated treatment. Material and Methods: Since 2008, 665 dosimetries were performed adopting the AIFM protocol. Pre-treatment dosimetry was performed 7 days before therapy with a 131I tracer activity: 4 blood samples were acquired and APPA whole body measurements were performed (2 h, 24 h, 48 h, 96 h). For in-therapy dosimetry a detector placed on patients’ bed provided AP counts (every 2 h). From blood and WB residence times, derived from the activity– time curves, doses to red marrow (AIFM and Traino methods) and to blood (EANM) were calculated. 62 pre and in-therapy doses per activity were compared. The dosimetric results of 83 repeated treatments were analyzed to investigate the possibility of using the first dosimetry as a reference. Results: In-therapy (7.8 ± 3.1 cGy/GBq) versus pre-therapy (7.2 ± 2.4 cGy/ GBq) red marrow doses showed a mean percentage difference of −2% ± 16% [range −36% to 31%]. In 57% of cases in-therapy red marrow doses were lower than pre-therapy ones. 61% of patients subjected to two treatments showed difference in dose per activity lower than 20% and only 12% greater than 40% (D2 = 0.84 D1). T-test for paired samples did not show a significant difference. The different dosimetric methods showed similar results. No dose correlation with thyroid hormones was found. Conclusions: Pre and in-therapy red marrow and blood dosimetry may represent an important tool to personalize metastatic thyroid cancer treatment,
Abstracts/Physica Medica 32 (2016) e97–e115
C.373 A STUDY OF MYOCARDIAL TOMOSCINTIGRAPHY BY SEMI-QUANTITATIVE ANALYSIS L. Pagan *,a, E. Cason b, S. Zoboli b, G. Fierro a, G. Lucchi b, R. Soavi a, P. Berardi a. a Fisica Sanitaria, Azienda USL, Bologna, Italy; b Medicina Nucleare, Azienda USL, Bologna, Italy Introduction: In order to verify the possible sensitivity variation using semiquantitative analysis, a comparison was performed between myocardial tomoscintigraphy of a phantom under different setup and equipment, along with a clinical cases review. Materials and Methods: Acquisitions were carried out with heart insert ECT/CAR/I, positioned inside the cylindrical phantom ‘Standard-Jaszczak’ and equipped by two warm sectors (one with 50% of phantom activity concentration, the other with 20%). Scans were performed both by a dedicated gamma camera (CardioMD – Philips) under different setup (i.e. by different distances between detectors and phantom), and by a General Purpose gamma camera (Infinia – GE). Images were processed using the Filtered Back Projection (FBP) algorithm and, when possible, the iterative one (Astonish – Philips). Then, comparisons between different acquisitions were performed using the regional perfusion semi-quantitative analysis with polar maps. Finally, a patient’s case review was carried out. Results: In all FBP images the 50% insert involved 3 segments of maps, including 2 identified as pathological, while the 20% one has involved 5 of which only 3 are pathological. In CardioMD images reconstructed with Astonish, the 50% insert involved 2 segments of maps, both pathological, while the 20% one has involved 4, all reported as pathological. Positive patients’ review also showed higher scores when iterative reconstruction was used, while in negative patients there were no differences. Conclusions: Semi-quantitative analysis with polar maps showed that there are no significant differences between the images acquired with different setup and equipment, when reconstructed by FBP. The use of the Astonish iterative algorithm instead has highlighted, compared to FBP, greater sensitivity both in phantom and in patients. http://dx.doi.org/10.1016/j.ejmp.2016.01.379
C.374 STUDY OF WHOLE BODY RESIDENCE TIMES FOR 131I TREATMENT OF THYROID CANCER M. Paoli *, E. Di Nicola, P. D’Avenia, M. Camarda, L. Montani, G. Rossi, S. Fattori. ASUR Marche, Macerata, Italy Introduction: The existence of a rare and precious archive, which contains measures of whole body counts for 1156 patients affected from thyroid carcinoma and subjected to ablation therapy with 131I, was the start for this study which aims to establish a reference standard for the residence times of 131I for patients hospitalized in nuclear medicine department. Materials and Methods: The method is based on the measures of total body counts, made by Geiger–Müller counters present in protected patient rooms, after administration of therapeutic activity of 131I in order to ablate the thyroid remnant. Patients were divided into two groups: 869 at first treatment with 131I and 287 treated with 131I for persistent disease after first treatment; for each of them the measures of total body counts have been normalized with the first measure and then it was calculated the residence time in the whole body through a bi-exponential fit of the counts/time curve. The concept of residence time is expressed in units of time but it is the number of nuclear transitions that occur in a certain region in a time interval normalized to the activity administered (Bq-s/Bq or μCi-h/μCi). Results: The results obtained for residence times are: First treatment: mean [h] 15.89, standard deviation 5.87, IC at 95% [15.50;16.28]; nth treatment: mean [h] 19.07, standard deviation 6.45, IC at 95% [18.33;19.82]. Conclusions: The efficacy of the nuclear medicine therapy is connected to the absorbed dose by the target that strongly depends on the time in which the radioiodine remains inside the tumor cell.
From the results it is evident that the mechanism of wash-out of the radioiodine I in whole body is slower for patients reprocessed. The high abundance of patients made it possible to calculate precise estimates of the confidence level of residence time’s average value; also the two intervals are quite distinct as thus also the two statistical populations. http://dx.doi.org/10.1016/j.ejmp.2016.01.380
C.375 RETROSPECTIVE ANALYSIS OF DOSE–RESPONSE FOR HCC LESIONS TREATED WITH 90Y RESIN MICROSPHERES C. Pettinato *,a, C. Mosconi b, A. Cappelli b, S. Civollani a, P. Pini c, F. Monari d, B. Angelelli e, E. Nobili e, S. Fanti f, R. Golfieri b. a U.O. Fisica Sanitaria, AOU S.Orsola Malpighi, Bologna, Italy; b U.O. Radiologia, AOU S.Orsola Malpighi, Bologna, Italy; c U.O. Medicina Interna, AOU S.Orsola Malpighi, Bologna, Italy; d U.O. Radioterapia, AOU S.Orsola Malpighi, Bologna, Italy; e U.O. Oncologia, AOU S.Orsola Malpighi, Bologna, Italy; f U.O. Medicina Nucleare, AOU S.Orsola Malpighi, Bologna, Italy Aim: The aim of this study was to evaluate the correlation between tumor dose and local tumor response. Materials and Methods: From September 2010 to October 2014, 48 patients affected by HCC have been treated with 90Y resin microspheres. All pts received an intra-hepatic infusion of 150 MBq of 99mTc-MAA to calculate lung and extra-hepatic shunts and to perform lesion and whole liver dosimetry using the MIRD formalism. The activity to be injected was calculated using the BSA formula and was modulated based on tumor and normal liver doses, limiting the dose to whole normal liver to about 30 Gy. Results: The mean injected 90Y activity was 1.5 (r: 0.4–2.4 GBq). The mean tumor volume was 286 cc (range: 43 cc–2566 cc), while the average dose was 258 Gy (range: 13–858 Gy). Tumors with smaller volumes received higher doses. The average doses to tumors with volumes below 100 cc, between 100 and 200 cc, between 200 and 500 cc and above 500 cc were respectively 436 Gy (95% IC: 267.6–603.5 Gy), 263 Gy (95% IC: 195.6– 329.4 Gy), 207.8 Gy (95% IC: 157.8–257.8 Gy) and 56.2 Gy (95% IC: 27.1– 85.3 Gy). 25/48 pts received an average tumor dose greater than 200 Gy. 9/25 pts showed a complete response and an average survival >12 months. 9/25 pts had a good response, while 7/25 pts had a stable response on the treated lesion but a worsening of the disease due to progression of nontreated lesions. 3/23 pts, who received less than 200 Gy, had a complete response of the treated lesion, 14/23 had a good response and 6 had stable disease. Our results suggest that big tumors (>300 cc) are responsive to lower average doses. Conclusions: Average tumor dose based on 99mTc-MAA SPECT images is a good prognostic value to predict tumor response to 90Y resin microsphere treatments in patients affected by HCC. Our results showed that 36% of tumors that received more than 200 Gy had complete response while 64% of tumors had stable or good response for more than one year. http://dx.doi.org/10.1016/j.ejmp.2016.01.381
C.376 RADIOMETABOLIC THERAPY WITH 131I FOR HYPERTHYROIDISM FROM GRAVES’ DISEASE. FIRST EXPERIENCES IN SASSARI HOSPITAL F. Pinna *,a, R. Bona a,b, C. Marchioni a,b, A. Poggiu a,b, M. Tamponi a,b, A. Spanu a, P.G. Marini a,b. a Azienda Ospedaliero Universitaria, Sassari, Italy; b Azienda Sanitaria Locale n° 1, Sassari, Italy Introduction: In our center we are treating patients with Graves’s disease with 131I for 2 years. The administered activity is customized by determining the parameters related to the kinetics of radiopharmaceutical uptake by a nonlinear mixedeffects model and effective thyroid volumes by echography. To emphasize the importance of this choice, we analyzed the dependence of the administered 131I activity by the calculation method. Materials and Methods: The method used allows to determine kinetic parameters (maximum uptake Umax and time effective half-life T1/2eff) fitting thyroid uptake measurements at 4, 24 and 72 hours from administration of 1,5 MBq of 131I, through a University of Massachusetts tool, which makes use of an algorithm based on results of reference [1].
Abstracts/Physica Medica 32 (2016) e97–e115
We assessed whether this method actually leads to significant differences in the evaluation of the activity to be administered than the simplified methods reported in the AIMN-AIFM guidelines, which provide the evaluation of T1/2eff from linear fit of the uptake at 24 and 72 h (or longer), and in the ICRP 53, which considers a standard 132 hours T1/2eff. In both of these simplified methods Umax is considered at 24th hour. The results are concerned with the first 7 patients (administered activities range from 102 to 303 MBq). Results: The results show that both simplified methods can give quite different results in the assessment of activity to be administered (maximum overestimation >40% and maximum underestimation close to 40%) if compared to the tool. Conclusions: The use of simplified methods can lead to an incorrect assessment of the activity to be administered and it should therefore be limited to special cases. Reference [1] Merrill S, Horowitz J, Traino AC, Chipkin SR, Hollot CV, Chait Y. Accuracy and optimal timing of activity measurements in estimating the absorbed dose of radioiodine in the treatment of Graves’ disease. Phys Med Biol 2011;56:557–71. http://dx.doi.org/10.1016/j.ejmp.2016.01.382
C.377 USE OF CUMULATIVE SUV VOLUME HISTOGRAM AS A NEW TOOL TO RADIOTHERAPY TREATMENT MONITORING P. Pisciotta *,a,b, A. Stefano a,c, G. Russo a,d, M.G. Sabini d, L.M. Valastro d, T. Licciardello d , C. D’Arrigo d , F. Marletta d , D. D’Urso a,b , G. Borasi a , M. Ippolito d, M.G. Gilardi a. a Istituto di Bioimmagini e Fisiologia Molecolare, Consiglio Nazionale delle Ricerche (IBFM CNR), Cefalù (PA), Italy; b Università degli Studi di Catania, Catania, Italy; c Dipartimento di Ingegneria Chimica, Gestionale, Informatica, Meccanica (DICGIM), Università degli Studi di Palermo, Palermo, Italy; d Azienda Ospedaliera per l’Emergenza Cannizzaro, Catania, Italy Introduction: This study investigated the biological evolution of tumor volume using [11C]-Methionine-PET (MET-PET) images. MET-PET diagnostic exams provide metabolic information about brain lesions impossible to obtain using other imaging techniques. Similar to the radiotherapy Dose– Volume Histogram (DVH), the Cumulative SUV–volume Histogram (CSH) represents the percentage of tumor metabolic volume higher than an SUV threshold, variable from 0 to the maximum SUV value. The aim of this study was to evaluate how the CSH could be used as a tool for the treatment monitoring in stereotactic radiosurgery. Materials and Methods: The patients selected for this study presented one or more brain metastases. The lesions were studied using metabolic METPET imaging before and after 3 months of the Gamma Knife treatment. The Radiotracer distribution changes were evaluated using the CSH parameters, that is: Area under the CSH, Uptake Intensity, etc. The CSH parameters were calculated for 14 patients using a homemade MATLAB tool. Results: According to the literature, the area under the CSH curve was considered as a quantitative index of the heterogeneity in the MET uptake inside the lesion volume. The percentage change of CSH was obtained as follows: δCSH(post vs pre) = 100*(CSHpost − CSHpre)/CSHpre, and this value was compared with the Nuclear Medicine physicians qualitative assessment. These CSH variations were in agreement with qualitative observation of METPET/CT images. Conclusions: The CSH could be a new tool to monitor the treatment followup for stereotactic radiosurgery. The CSH parameters seem to be correlated with the tumor response and permit a more accurate early assessing of therapy response. Future studies are needed to evaluate the threshold of the CSH parameter changes to discriminate between responders and non-responders. http://dx.doi.org/10.1016/j.ejmp.2016.01.383
C.378 NEW PROMISING SCINTILLATION CRYSTALS FOR MOLECULAR IMAGING APPLICATIONS: CRY018 AND CRY019 C. Polito *,a, M.N. Cinti b,c, R. Pellegrini b,c, R. Pani c,d. a SAIMLAL Department, Sapienza University of Rome, Rome, Italy; b Department of Molecular Medicine,
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Sapienza University of Rome, Rome, Italy; c INFN Roma I Section, Rome, Italy; d Department of Sciences and Medical and Surgical Biotechnologies, Sapienza University of Rome, Rome, Italy Introduction: A detailed investigation of new scintillation crystals, produced by CRYTUR spol. s r.o. (Czech Republic), is presented. Pulse height distributions have been measured as a function of photon energy, in order to evaluate the Energy Resolution. The crystals have shown promising performances for gamma ray imaging applications as the short scintillation decay time that makes these scintillation crystals attractive for the improvement of a wide range of applications in Nuclear Medicine, like PET and SPECT instrumentations. Materials and Methods: A couple of new mixed rare-earth silicate single crystal scintillation materials (CRY018 and CRY019) have been studied. The crystals have round shape and white painting on all sides, except on the one in contact with Photomultiplier Tubes. Their size is proper of a small Field of View gamma imager (50 mm diameter and 6 mm thickness). The crystals were irradiated with radioactive source with different photon energy in order to characterize their Energy Resolution. Subsequently the Spatial Linearity and Spatial Resolution were quantified with a scanning of the crystals surface with a 1 mm Tc99m point source. The fast decay time allows combining the crystals with fast timing applications (i.e. Silicon Photomultiplier). Results: The Energy Resolution is close to 16.3% for CRY019 and 12.4% for CRY018 at 122 keV (comparable with one of NaI:Tl that is 12%). About spatial linearity, the CRY019 crystal shows the worse linearity but the greater efficiency respect to the CRY018. Finally, the intrinsic spatial resolutions were 1.6 mm and 2 mm for CRY018 and CRY019 respectively. Conclusion: The satisfactory results in terms of Energy and Spatial Resolution suggest the employment of these crystals in many different applications. Moreover these materials are not hygroscopic, this means that they do not need to be contained in a sealed casing. Finally, all these great performances make the crystals attractive also for dual modality applications. http://dx.doi.org/10.1016/j.ejmp.2016.01.384
C.379 RED MARROW AND BLOOD DOSIMETRY IN 131I TREATMENT OF METASTATIC DIFFERENTIATED THYROID CARCINOMA: 7 YEARS EXPERIENCE AT MAURIZIANO HOSPITAL OF TURIN E. Richetta * ,a , C. Cutaia a , S. Valzano a , M. Pasquino a , G. Lo Moro a , G. Brusasco b, R.E. Pellerito b, M. Stasi a. a S.C. Fisica Sanitaria, AO Ordine Mauriziano di Torino, Torino, Italy; b S.C. Medicina Nucleare, AO Ordine Mauriziano di Torino, Torino, Italy Introduction: Radioiodine treatment of metastatic differentiated thyroid cancer is limited by red marrow toxicity. In our institution dosimetry to red marrow and blood is performed before and after therapy to individually determine the maximum tolerable 131I activity. The study shows the results obtained comparing different dosimetric methods, pre- and intherapy dosimetry and doses to patients with repeated treatment. Material and Methods: Since 2008, 665 dosimetries were performed adopting the AIFM protocol. Pre-treatment dosimetry was performed 7 days before therapy with a 131I tracer activity: 4 blood samples were acquired and APPA whole body measurements were performed (2 h, 24 h, 48 h, 96 h). For in-therapy dosimetry a detector placed on patients’ bed provided AP counts (every 2 h). From blood and WB residence times, derived from the activity– time curves, doses to red marrow (AIFM and Traino methods) and to blood (EANM) were calculated. 62 pre and in-therapy doses per activity were compared. The dosimetric results of 83 repeated treatments were analyzed to investigate the possibility of using the first dosimetry as a reference. Results: In-therapy (7.8 ± 3.1 cGy/GBq) versus pre-therapy (7.2 ± 2.4 cGy/ GBq) red marrow doses showed a mean percentage difference of −2% ± 16% [range −36% to 31%]. In 57% of cases in-therapy red marrow doses were lower than pre-therapy ones. 61% of patients subjected to two treatments showed difference in dose per activity lower than 20% and only 12% greater than 40% (D2 = 0.84 D1). T-test for paired samples did not show a significant difference. The different dosimetric methods showed similar results. No dose correlation with thyroid hormones was found. Conclusions: Pre and in-therapy red marrow and blood dosimetry may represent an important tool to personalize metastatic thyroid cancer treatment,