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Individualized dosimetry for patients with graves’ disease
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Abstracts / Physica Medica 32 (2016) 284–339
sisted of three isocentres and three overlapping arcs.The prescribed dose was 95% of target volume receiving dose of 12 Gy.Mean dose to lung and kidney were restricted less than 9.0 Gy. Results. An average total delivery time was determined 835 ± 86 seconds and an average monitor unit (MU)s was determined 2202 ± 254 MUs for double arc VMAT technique. This study demonstrates that double arc VMAT technique has got less MUs than other technique but an average delivery time is %17 more than single arc VMAT technique. When we compared organ at risk (OAR)s, we had less dose and better dose coverage to target with double arc VMAT technique. Conclusion. The tecnique for TBI using VMAT was found feasible. The results show that dose coverage of target and OAR’s doses also depend significantly VMAT techniques. Based on the results we have decided to plan TBI in our clinic with double arc VMAT technique. http://dx.doi.org/10.1016/j.ejmp.2016.07.198
HODGKIN LYMPHOMA (HL) TREATMENT USING VARIAN ECLIPSE IRREGULAR SURFACE COMPENSATOR. A DOSIMETRIC ANALYSIS AND CLINICAL RESULTS F. Herrera-Martinez *, D. Toledano-Cuevas, M. Rodriguez-Ponce, J. Altamirano-Garcia Instituto Nacional de Cancerología, Mexico city, Mexico Corresponding author.
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Introduction. A recommended technique for a radiation therapy treatment for HL is a mantle field technique. This technique in most of the cases represents a challenge for the dose calculation not only for the irregularity and size of the field but for the anatomical area to cover; going from the neck to mediastinal region and in some cases up to the axillar regions, thus represents an important problem when the required dose distribution has to be uniform enough to achieve coverage suggested standards, especially for those anatomies with short neck and/or fat chests which leaded to an undesired hot spots on neck and chin mostly and their correspondent side effects. In order to avoid this and improved the treatment, since 2010, mantle techniques are treated with compensators observing improvements in the dose distribution obtained. Purpose. To improved quality on mantle technique for HL diminishing side effects. Method. Each of this treatment plans were calculated using the Varian Eclipse irregular surface compensator calculation technique and verified using gamma index criteria. Each plan were compared with the blocked field of the same size, shape and energy. Results and conclusions. On the dosimetric comparisons we observed a hot spots from 5% to 12% lower than the observed with a conventional technique and an improved hot spot localization according to clinical criteria. Clinically, side effects expected according to experience with blocked fields were diminished on about 70% of the cases on a five years follow-up. http://dx.doi.org/10.1016/j.ejmp.2016.07.199
INDIVIDUALIZED DOSIMETRY FOR PATIENTS WITH GRAVES’ DISEASE F.J. Luís Simón a,*, I. Cuenca Cuenca b, D. Jimenez Felstrom a, E. Lopez Rodriguez b a Medical Physics Department, Hospital Universitario Virgen del Rocío, Seville, Spain b Medicine Nuclear Department, Hospital Universitario Virgen del Rocío, Seville, Spain ⇑ Corresponding author.
Introduction. Following Directive 2013/59 Euratom, all therapeutic exposures of target volumes shall be individually planned and their delivery appropriately verified. We have developed a homemade software for I-131 dosimetry in hyperthyroid patients using gammacamera and capture probe for prior and post treatment. Purpose. This study describes the dosimetry method, the differences between pre and post treatment purposes, and compare its results. Materials and methods. We base our procedure on the EANM Dosimetry Committee Guidelines using an INa Probe for uptake measurements at 2, 24 and 96 h after administration of 25 lCi tracer activity (also measured before its administration) and two Tc-99m planar images to estimate the thyroid mass. A two compartimental model is used to calculate the required activity to achieve 160 Gy to the target. Two uptake measurements are acquired at 96 and 168 h post-treatment to calculate the real absorbed dose to the thyroid, using a monocompartimental model and dead time correction for saturation effect through a previous probe calibration curve. 78 patients treated during 2015 have been analyzed. Results. 163,1 Gy and 37,7 Gy are the average and standard deviation of administered absorbed doses, ranging from 87,3 Gy to 240,1 Gy. The mean activity to be administered according the used model is 9,1 mCi which differs from previously used (Marinelli algorithm, 7,3 mCi) and administered (8,9 mCi). Differences of means between activities by Marinelli and by our method using t-Student are significant (p < 0.05) Conclusion. Individualized pre and post treatment dosimetry for hyperthyroidism I-131 therapy is mandatory. http://dx.doi.org/10.1016/j.ejmp.2016.07.200
177 LU-OCTREOTATE PEPTIDE RECEPTOR RADIONUCLIDE THERAPY OF NEUROENDOCRINE TUMOURS: DOSIMETRY OF PERSONNEL AND CAREGIVERS A.P. Stefanoyiannis *, T. Liotsou, S. Ioannidou, S.N. Chatziioannou
Nuclear Medicine Unit, University General Hospital of Athens ‘‘Attikon”, 1 Rimini St, Athens 12462, Greece ⇑ Corresponding author. Introduction. The clinical application of 177Lu-Octreotate Peptide Receptor Radionuclide Therapy (PRRTs) is well-established. The relatively long physical half life of 177Lu, along with the fact that it is both a betta and gamma emitter, necessitates investigation of the radiation burden to the personnel and caregivers involved. Purpose. The purpose of this study was to measure the effective dose to the personnel per administered dose, as well as the effective dose to the caregivers during the immediate p.i. period. Materials and Methods. Dosimetry measurements were performed for both personnel and caregivers involved in 45 administrations between June ’13–December ’15. Personnel whole-body doses were recorded on a monthly basis. Dose rate measurements at 1 m distance from the patient were recorded, at time instances 0– 30 min and 30–120 min p.i. TLD dosimeters were provided to caregivers to assess their exposure in the time intervals 0–3 days, 3– 7 days and 0–7 days p.i. Results. The personnel’s average dose was 32.7 lSv/administered dose. The average dose rate at 1 m distance from the patient 0–30 min p.i. was 47 lSv/hr (range:15–100 lSv/hr), decreasing to 26 lSv/hr 30–120 min p.i. (range:10–50 lSv/hr). The average recorded dose to caregivers was 0.065 mSv in the first 3 days p.i. (range:0–0.14 mSv), 0.035 mSv in the next 4 days p.i. (range:0– 0.15 mSv) and 0.100 mSv in the whole dosimetric period (range:0– 0.29 mSv).
Abstracts / Physica Medica 32 (2016) 284–339
sisted of three isocentres and three overlapping arcs.The prescribed dose was 95% of target volume receiving dose of 12 Gy.Mean dose to lung and kidney were restricted less than 9.0 Gy. Results. An average total delivery time was determined 835 ± 86 seconds and an average monitor unit (MU)s was determined 2202 ± 254 MUs for double arc VMAT technique. This study demonstrates that double arc VMAT technique has got less MUs than other technique but an average delivery time is %17 more than single arc VMAT technique. When we compared organ at risk (OAR)s, we had less dose and better dose coverage to target with double arc VMAT technique. Conclusion. The tecnique for TBI using VMAT was found feasible. The results show that dose coverage of target and OAR’s doses also depend significantly VMAT techniques. Based on the results we have decided to plan TBI in our clinic with double arc VMAT technique. http://dx.doi.org/10.1016/j.ejmp.2016.07.198
HODGKIN LYMPHOMA (HL) TREATMENT USING VARIAN ECLIPSE IRREGULAR SURFACE COMPENSATOR. A DOSIMETRIC ANALYSIS AND CLINICAL RESULTS F. Herrera-Martinez *, D. Toledano-Cuevas, M. Rodriguez-Ponce, J. Altamirano-Garcia Instituto Nacional de Cancerología, Mexico city, Mexico Corresponding author.
⇑
Introduction. A recommended technique for a radiation therapy treatment for HL is a mantle field technique. This technique in most of the cases represents a challenge for the dose calculation not only for the irregularity and size of the field but for the anatomical area to cover; going from the neck to mediastinal region and in some cases up to the axillar regions, thus represents an important problem when the required dose distribution has to be uniform enough to achieve coverage suggested standards, especially for those anatomies with short neck and/or fat chests which leaded to an undesired hot spots on neck and chin mostly and their correspondent side effects. In order to avoid this and improved the treatment, since 2010, mantle techniques are treated with compensators observing improvements in the dose distribution obtained. Purpose. To improved quality on mantle technique for HL diminishing side effects. Method. Each of this treatment plans were calculated using the Varian Eclipse irregular surface compensator calculation technique and verified using gamma index criteria. Each plan were compared with the blocked field of the same size, shape and energy. Results and conclusions. On the dosimetric comparisons we observed a hot spots from 5% to 12% lower than the observed with a conventional technique and an improved hot spot localization according to clinical criteria. Clinically, side effects expected according to experience with blocked fields were diminished on about 70% of the cases on a five years follow-up. http://dx.doi.org/10.1016/j.ejmp.2016.07.199
INDIVIDUALIZED DOSIMETRY FOR PATIENTS WITH GRAVES’ DISEASE F.J. Luís Simón a,*, I. Cuenca Cuenca b, D. Jimenez Felstrom a, E. Lopez Rodriguez b a Medical Physics Department, Hospital Universitario Virgen del Rocío, Seville, Spain b Medicine Nuclear Department, Hospital Universitario Virgen del Rocío, Seville, Spain ⇑ Corresponding author.
Introduction. Following Directive 2013/59 Euratom, all therapeutic exposures of target volumes shall be individually planned and their delivery appropriately verified. We have developed a homemade software for I-131 dosimetry in hyperthyroid patients using gammacamera and capture probe for prior and post treatment. Purpose. This study describes the dosimetry method, the differences between pre and post treatment purposes, and compare its results. Materials and methods. We base our procedure on the EANM Dosimetry Committee Guidelines using an INa Probe for uptake measurements at 2, 24 and 96 h after administration of 25 lCi tracer activity (also measured before its administration) and two Tc-99m planar images to estimate the thyroid mass. A two compartimental model is used to calculate the required activity to achieve 160 Gy to the target. Two uptake measurements are acquired at 96 and 168 h post-treatment to calculate the real absorbed dose to the thyroid, using a monocompartimental model and dead time correction for saturation effect through a previous probe calibration curve. 78 patients treated during 2015 have been analyzed. Results. 163,1 Gy and 37,7 Gy are the average and standard deviation of administered absorbed doses, ranging from 87,3 Gy to 240,1 Gy. The mean activity to be administered according the used model is 9,1 mCi which differs from previously used (Marinelli algorithm, 7,3 mCi) and administered (8,9 mCi). Differences of means between activities by Marinelli and by our method using t-Student are significant (p < 0.05) Conclusion. Individualized pre and post treatment dosimetry for hyperthyroidism I-131 therapy is mandatory. http://dx.doi.org/10.1016/j.ejmp.2016.07.200
177 LU-OCTREOTATE PEPTIDE RECEPTOR RADIONUCLIDE THERAPY OF NEUROENDOCRINE TUMOURS: DOSIMETRY OF PERSONNEL AND CAREGIVERS A.P. Stefanoyiannis *, T. Liotsou, S. Ioannidou, S.N. Chatziioannou
Nuclear Medicine Unit, University General Hospital of Athens ‘‘Attikon”, 1 Rimini St, Athens 12462, Greece ⇑ Corresponding author. Introduction. The clinical application of 177Lu-Octreotate Peptide Receptor Radionuclide Therapy (PRRTs) is well-established. The relatively long physical half life of 177Lu, along with the fact that it is both a betta and gamma emitter, necessitates investigation of the radiation burden to the personnel and caregivers involved. Purpose. The purpose of this study was to measure the effective dose to the personnel per administered dose, as well as the effective dose to the caregivers during the immediate p.i. period. Materials and Methods. Dosimetry measurements were performed for both personnel and caregivers involved in 45 administrations between June ’13–December ’15. Personnel whole-body doses were recorded on a monthly basis. Dose rate measurements at 1 m distance from the patient were recorded, at time instances 0– 30 min and 30–120 min p.i. TLD dosimeters were provided to caregivers to assess their exposure in the time intervals 0–3 days, 3– 7 days and 0–7 days p.i. Results. The personnel’s average dose was 32.7 lSv/administered dose. The average dose rate at 1 m distance from the patient 0–30 min p.i. was 47 lSv/hr (range:15–100 lSv/hr), decreasing to 26 lSv/hr 30–120 min p.i. (range:10–50 lSv/hr). The average recorded dose to caregivers was 0.065 mSv in the first 3 days p.i. (range:0–0.14 mSv), 0.035 mSv in the next 4 days p.i. (range:0– 0.15 mSv) and 0.100 mSv in the whole dosimetric period (range:0– 0.29 mSv).