Impact of missing attenuation and scatter corrections on 99mTc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images

F. Botta, M. Ferrari, C. Chiesa, S. Vitali, F. Guerriero, M.C.D. Nile, M. Mira, L. Lorenzon, M. Pacilio, M. Cremonesi

Research output: Contribution to journalArticle

Abstract

Purpose: To investigate the clinical implication of performing pre-treatment dosimetry for 90Y-microspheres liver radioembolization on 99mTc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Methods: Twenty-five patients treated with SIR-Spheres® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere® at Istituto Nazionale Tumori were considered. For each acquired 99mTc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL − T and HIL = IL − T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. Results: NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95% confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest %VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. Conclusions: The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. © 2018 American Association of Physicists in Medicine
Original languageEnglish
Pages (from-to)1684-1698
Number of pages15
JournalMedical Physics
Volume45
Issue number4
DOIs
Publication statusPublished - 2018

Fingerprint

Single-Photon Emission-Computed Tomography
Calibration
Liver
Uncertainty
Prescriptions
Reference Values
Microspheres
Individuality
Noise
Therapeutics
Medicine
Confidence Intervals

Keywords

  • internal dosimetry accuracy
  • liver radioembolization
  • SPECT corrections
  • SPECT quantification
  • voxel dosimetry
  • macrosalb tc 99m
  • yttrium 90
  • adult
  • aged
  • Article
  • cancer radiotherapy
  • clinical article
  • comparative study
  • controlled study
  • dosimetry
  • external beam radiotherapy
  • female
  • human
  • image reconstruction
  • liver cell carcinoma
  • liver toxicity
  • male
  • radiation attenuation
  • radiation dose distribution
  • radioembolization
  • reference value
  • retrospective study
  • single photon emission computed tomography
  • three dimensional imaging
  • treatment planning
  • uncertainty
  • artificial embolization
  • calibration
  • diagnostic imaging
  • image processing
  • imaging phantom
  • liver
  • liver tumor
  • middle aged
  • Monte Carlo method
  • radiation response
  • radiation scattering
  • radiometry
  • signal noise ratio
  • Adult
  • Calibration
  • Embolization, Therapeutic
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Liver
  • Liver Neoplasms
  • Male
  • Middle Aged
  • Monte Carlo Method
  • Phantoms, Imaging
  • Radiometry
  • Retrospective Studies
  • Scattering, Radiation
  • Signal-To-Noise Ratio
  • Technetium Tc 99m Aggregated Albumin
  • Tomography, Emission-Computed, Single-Photon
  • Uncertainty

Cite this

@article{f59ab9cebef44629a3a3dd5097b0bec9,
title = "Impact of missing attenuation and scatter corrections on 99mTc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images",
abstract = "Purpose: To investigate the clinical implication of performing pre-treatment dosimetry for 90Y-microspheres liver radioembolization on 99mTc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Methods: Twenty-five patients treated with SIR-Spheres{\circledR} at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere{\circledR} at Istituto Nazionale Tumori were considered. For each acquired 99mTc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL − T and HIL = IL − T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5{\%} significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error ({\%}VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. Results: NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95{\%} confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest {\%}VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. Conclusions: The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. {\circledC} 2018 American Association of Physicists in Medicine",
keywords = "internal dosimetry accuracy, liver radioembolization, SPECT corrections, SPECT quantification, voxel dosimetry, macrosalb tc 99m, yttrium 90, adult, aged, Article, cancer radiotherapy, clinical article, comparative study, controlled study, dosimetry, external beam radiotherapy, female, human, image reconstruction, liver cell carcinoma, liver toxicity, male, radiation attenuation, radiation dose distribution, radioembolization, reference value, retrospective study, single photon emission computed tomography, three dimensional imaging, treatment planning, uncertainty, artificial embolization, calibration, diagnostic imaging, image processing, imaging phantom, liver, liver tumor, middle aged, Monte Carlo method, radiation response, radiation scattering, radiometry, signal noise ratio, Adult, Calibration, Embolization, Therapeutic, Female, Humans, Image Processing, Computer-Assisted, Liver, Liver Neoplasms, Male, Middle Aged, Monte Carlo Method, Phantoms, Imaging, Radiometry, Retrospective Studies, Scattering, Radiation, Signal-To-Noise Ratio, Technetium Tc 99m Aggregated Albumin, Tomography, Emission-Computed, Single-Photon, Uncertainty",
author = "F. Botta and M. Ferrari and C. Chiesa and S. Vitali and F. Guerriero and M.C.D. Nile and M. Mira and L. Lorenzon and M. Pacilio and M. Cremonesi",
note = "Cited By :2 Export Date: 5 February 2019 CODEN: MPHYA Correspondence Address: Botta, F.; Medical Physics Service, Department of Medical Images and Radiation Sciences, Istituto Europeo di OncologiaItaly; email: francesca.botta@ieo.it Chemicals/CAS: macrosalb tc 99m, 54277-47-3; yttrium 90, 10098-91-6; Technetium Tc 99m Aggregated Albumin Tradenames: SIR-Spheres; TheraSphere References: Ahmadzadehfar, H., Biersack, H.J., Ezziddin, S., Radioembolization of liver tumors with Yttrium-90 microspheres (2010) Semin Nucl Med, 40, pp. 105-121; Dawson, L.A., Ten Haken, R.H., Partial volume tolerance of the liver to radiation (2005) Semin Radiat Oncol, 15, pp. 279-283; Dezarn, W.A., Cessna, J.T., DeWerd, L.A., Feng, W., Gates, V.L., Salama, J., Recommendations of the American Association of Physicists in Medicine on dosimetry, imaging, and quality assurance procedures for 90Y microsphere brachytherapy in the treatment of hepatic malignancies (2011) Med Phys, 38, pp. 4824-4845; Nath, R., Rivard, M.J., DeWer, L.A., Guidelines by the AAPM and GEC-ESTRO on the use of innovative brachytherapy devices and applications: report of Task Group 167 (2016) Med Phys, 43, pp. 3178-3205; Giammarile, F., Bodei, L., Chiesa, C., EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds (2011) Eur J Nucl Med Mol Imaging, 38, pp. 1393-1406; Garin, E., Rolland, Y., Laffont, S., Edeline, J., Clinical impact of 99mTc-MAA SPECT/CT-based dosimetry in the radioembolization of liver malignancies with 90Y-loaded microspheres (2016) Eur J Nucl Med Mol Imaging, 43, pp. 559-575; Bardies, M., Buvat, I., Dosimetry in nuclear medicine therapy: what are the specifics in image quantification for dosimetry? (2011) Q J Nucl Med Mol Imaging, 55, pp. 5-20; Quantitative Nuclear Medicine imaging: concepts, requirements and methods, , 2014; IAEA Human Health reports 9; Dewaraya, Y.K., Frey, E.C., Sgouros, G., MIRD Pamphlet No. 23: quantitative SPECT for patient-specific 3-dimensional dosimetry in internal radionuclide therapy (2012) J Nucl Med, 53, pp. 1310-1325; Pacilio, M., Ferrari, M., Chiesa, C., Impact of SPECT corrections on 3D-dosimetry for liver transarterial radioembolization using the relative calibration methodology (2016) Med Phys, 43, pp. 4053-4064; Ljungberg, M., The SIMIND Monte Carlo program (2013) Monte Carlo Calculations in Nuclear Medicine, pp. 111-127. , In, Boca Raton, CRC Press/Taylor & Francis; Bolch, W.E., Bouchet, L.G., Robertson, J.S., MIRD Pamphlet No. 17: the dosimetry of nonuniform activity distributions—radionuclide S values at the voxel level (1999) J Nucl Med, 40, pp. 11S-36S; Lanconelli, N., Pacilio, M., LoMeo, S., A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions (2012) Phys Med Biol, 57, pp. 517-533; Walrand, S., Hesse, M., Jamar, F., Lhommel, R., A hepatic dose-toxicity model opening the way toward individualized radioembolization planning (2014) J Nucl Med, 55, pp. 1317-1322; Lau, W.Y., Kennedy, A.S., Kim, Y.H., Patient selection and activity planning guide for selective internal radiotherapy with Yttrium-90 resin microspheres (2012) Int J Radiat Oncol Biol Phys, 82, pp. 401-407; Chiesa, C., Mira, M., Maccauro, M., Radioembolization of hepatocarcinoma with 90-Y glass microspheres: development of an individualized treatment planning strategy based on dosimetry and radiobiology (2015) Eur J Nucl Med Mol Im, 42, pp. 1718-1738; Walrand, S., Hesse, M., Chiesa, C., Lhommel, R., Jamar, F., The low hepatic toxicity per Gray of 90Y glasses microspheres is linked to their transport in the arterial tree favoring a nonuniform trapping as observed in posttherapy PET imaging (2014) J Nucl Med, 55, pp. 1-6; SIR-Spheres{\circledR} microspheres, , http://www.sirtex.com/us/clinicians/package-insert/2005; Therasphere{\circledR} by BTG, , http://www.therasphere.com; Pasciak, A.S., Bourgeoius, A.C., Bradley, Y.C., A comparison of techniques for 90Y PET/CT image-based dosimetry following radioembolization with resin microspheres (2014) Front Oncol., 4, pp. 1-10; Dewaraja, Y.K., Ljungberg, M., Fessler, J.A., 3-D Monte Carlo-based scatter compensation in quantitative I-131 SPECT reconstruction (2006) IEEE Trans Nucl Sci, 53, pp. 181-188; King, M.A., Glick, S.J., Pretorius, P.H., Attenuation, scatter, and spatial resolution compensation in SPECT (2004) Emission Tomography: The Fundamentals of PET and SPECT, pp. 473-498. , In, Wernick MN, Aarsvold JN, eds., Waltham, Elsevier Academic Press; Willowson, K.P., Hayes, A.R., Chan, D.L.H., Clinical and imaging-based prognostic factors in radioembolisation of liver metastases from colorectal cancer: a retrospective exploratory analysis (2017) EJNMMI Res., 7, pp. 46-58; Garin, E., Rolland, Y., Edeline, J., Personalized dosimetry with intensification using 90Y-loaded glass microsphere radioembolization includes prolonged overall survival in hepatocellular carcinoma patients with portal vein thrombosis (2015) J Nul Med., 56, pp. 339-346; Cremonesi, M., Chiesa, C., Strigari, L., Radioembolization of hepatic lesions from a radiobiology and dosimetric perspective (2014) Front Oncol., 4, pp. 1-20; Garin, E., Lenoir, L., Edeline, J., Boosted selective internal radiation therapy with 90Y-loaded glass microspheres (B-SIRT) for hepatocellular carcinoma patients: a new promising concept (2013) Eur J Nucl Med Mol Imaging, 40, pp. 1057-1068; Strigari, L., Sciuto, R., Rea, S., Efficacy and toxicity related to treatment of hepatocellular carcinoma with 90Y-SIR spheres: radiobiologic considerations (2010) J Nucl Med, 51, pp. 1377-1385; Jones, L.C., Hoban, P.W., Treatment plan comparison using equivalent uniform biologically effective dose (EUBED) (2000) Phys Med Biol, 45, pp. 159-170; Kao, Y.H., Steinberg, J.D., Tay, Y.S., Post-radioembolization yttrium-90 PET/CT-part 2: dose-response and tumor predictive dosimetry for resin microspheres (2013) EJNMMI Res, 3, pp. 57-68",
year = "2018",
doi = "10.1002/mp.12774",
language = "English",
volume = "45",
pages = "1684--1698",
journal = "Medical Physics",
issn = "0094-2405",
publisher = "John Wiley and Sons Ltd",
number = "4",

}

TY - JOUR

T1 - Impact of missing attenuation and scatter corrections on 99mTc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images

AU - Botta, F.

AU - Ferrari, M.

AU - Chiesa, C.

AU - Vitali, S.

AU - Guerriero, F.

AU - Nile, M.C.D.

AU - Mira, M.

AU - Lorenzon, L.

AU - Pacilio, M.

AU - Cremonesi, M.

N1 - Cited By :2 Export Date: 5 February 2019 CODEN: MPHYA Correspondence Address: Botta, F.; Medical Physics Service, Department of Medical Images and Radiation Sciences, Istituto Europeo di OncologiaItaly; email: francesca.botta@ieo.it Chemicals/CAS: macrosalb tc 99m, 54277-47-3; yttrium 90, 10098-91-6; Technetium Tc 99m Aggregated Albumin Tradenames: SIR-Spheres; TheraSphere References: Ahmadzadehfar, H., Biersack, H.J., Ezziddin, S., Radioembolization of liver tumors with Yttrium-90 microspheres (2010) Semin Nucl Med, 40, pp. 105-121; Dawson, L.A., Ten Haken, R.H., Partial volume tolerance of the liver to radiation (2005) Semin Radiat Oncol, 15, pp. 279-283; Dezarn, W.A., Cessna, J.T., DeWerd, L.A., Feng, W., Gates, V.L., Salama, J., Recommendations of the American Association of Physicists in Medicine on dosimetry, imaging, and quality assurance procedures for 90Y microsphere brachytherapy in the treatment of hepatic malignancies (2011) Med Phys, 38, pp. 4824-4845; Nath, R., Rivard, M.J., DeWer, L.A., Guidelines by the AAPM and GEC-ESTRO on the use of innovative brachytherapy devices and applications: report of Task Group 167 (2016) Med Phys, 43, pp. 3178-3205; Giammarile, F., Bodei, L., Chiesa, C., EANM procedure guideline for the treatment of liver cancer and liver metastases with intra-arterial radioactive compounds (2011) Eur J Nucl Med Mol Imaging, 38, pp. 1393-1406; Garin, E., Rolland, Y., Laffont, S., Edeline, J., Clinical impact of 99mTc-MAA SPECT/CT-based dosimetry in the radioembolization of liver malignancies with 90Y-loaded microspheres (2016) Eur J Nucl Med Mol Imaging, 43, pp. 559-575; Bardies, M., Buvat, I., Dosimetry in nuclear medicine therapy: what are the specifics in image quantification for dosimetry? (2011) Q J Nucl Med Mol Imaging, 55, pp. 5-20; Quantitative Nuclear Medicine imaging: concepts, requirements and methods, , 2014; IAEA Human Health reports 9; Dewaraya, Y.K., Frey, E.C., Sgouros, G., MIRD Pamphlet No. 23: quantitative SPECT for patient-specific 3-dimensional dosimetry in internal radionuclide therapy (2012) J Nucl Med, 53, pp. 1310-1325; Pacilio, M., Ferrari, M., Chiesa, C., Impact of SPECT corrections on 3D-dosimetry for liver transarterial radioembolization using the relative calibration methodology (2016) Med Phys, 43, pp. 4053-4064; Ljungberg, M., The SIMIND Monte Carlo program (2013) Monte Carlo Calculations in Nuclear Medicine, pp. 111-127. , In, Boca Raton, CRC Press/Taylor & Francis; Bolch, W.E., Bouchet, L.G., Robertson, J.S., MIRD Pamphlet No. 17: the dosimetry of nonuniform activity distributions—radionuclide S values at the voxel level (1999) J Nucl Med, 40, pp. 11S-36S; Lanconelli, N., Pacilio, M., LoMeo, S., A free database of radionuclide voxel S values for the dosimetry of nonuniform activity distributions (2012) Phys Med Biol, 57, pp. 517-533; Walrand, S., Hesse, M., Jamar, F., Lhommel, R., A hepatic dose-toxicity model opening the way toward individualized radioembolization planning (2014) J Nucl Med, 55, pp. 1317-1322; Lau, W.Y., Kennedy, A.S., Kim, Y.H., Patient selection and activity planning guide for selective internal radiotherapy with Yttrium-90 resin microspheres (2012) Int J Radiat Oncol Biol Phys, 82, pp. 401-407; Chiesa, C., Mira, M., Maccauro, M., Radioembolization of hepatocarcinoma with 90-Y glass microspheres: development of an individualized treatment planning strategy based on dosimetry and radiobiology (2015) Eur J Nucl Med Mol Im, 42, pp. 1718-1738; Walrand, S., Hesse, M., Chiesa, C., Lhommel, R., Jamar, F., The low hepatic toxicity per Gray of 90Y glasses microspheres is linked to their transport in the arterial tree favoring a nonuniform trapping as observed in posttherapy PET imaging (2014) J Nucl Med, 55, pp. 1-6; SIR-Spheres® microspheres, , http://www.sirtex.com/us/clinicians/package-insert/2005; Therasphere® by BTG, , http://www.therasphere.com; Pasciak, A.S., Bourgeoius, A.C., Bradley, Y.C., A comparison of techniques for 90Y PET/CT image-based dosimetry following radioembolization with resin microspheres (2014) Front Oncol., 4, pp. 1-10; Dewaraja, Y.K., Ljungberg, M., Fessler, J.A., 3-D Monte Carlo-based scatter compensation in quantitative I-131 SPECT reconstruction (2006) IEEE Trans Nucl Sci, 53, pp. 181-188; King, M.A., Glick, S.J., Pretorius, P.H., Attenuation, scatter, and spatial resolution compensation in SPECT (2004) Emission Tomography: The Fundamentals of PET and SPECT, pp. 473-498. , In, Wernick MN, Aarsvold JN, eds., Waltham, Elsevier Academic Press; Willowson, K.P., Hayes, A.R., Chan, D.L.H., Clinical and imaging-based prognostic factors in radioembolisation of liver metastases from colorectal cancer: a retrospective exploratory analysis (2017) EJNMMI Res., 7, pp. 46-58; Garin, E., Rolland, Y., Edeline, J., Personalized dosimetry with intensification using 90Y-loaded glass microsphere radioembolization includes prolonged overall survival in hepatocellular carcinoma patients with portal vein thrombosis (2015) J Nul Med., 56, pp. 339-346; Cremonesi, M., Chiesa, C., Strigari, L., Radioembolization of hepatic lesions from a radiobiology and dosimetric perspective (2014) Front Oncol., 4, pp. 1-20; Garin, E., Lenoir, L., Edeline, J., Boosted selective internal radiation therapy with 90Y-loaded glass microspheres (B-SIRT) for hepatocellular carcinoma patients: a new promising concept (2013) Eur J Nucl Med Mol Imaging, 40, pp. 1057-1068; Strigari, L., Sciuto, R., Rea, S., Efficacy and toxicity related to treatment of hepatocellular carcinoma with 90Y-SIR spheres: radiobiologic considerations (2010) J Nucl Med, 51, pp. 1377-1385; Jones, L.C., Hoban, P.W., Treatment plan comparison using equivalent uniform biologically effective dose (EUBED) (2000) Phys Med Biol, 45, pp. 159-170; Kao, Y.H., Steinberg, J.D., Tay, Y.S., Post-radioembolization yttrium-90 PET/CT-part 2: dose-response and tumor predictive dosimetry for resin microspheres (2013) EJNMMI Res, 3, pp. 57-68

PY - 2018

Y1 - 2018

N2 - Purpose: To investigate the clinical implication of performing pre-treatment dosimetry for 90Y-microspheres liver radioembolization on 99mTc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Methods: Twenty-five patients treated with SIR-Spheres® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere® at Istituto Nazionale Tumori were considered. For each acquired 99mTc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL − T and HIL = IL − T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. Results: NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95% confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest %VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. Conclusions: The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. © 2018 American Association of Physicists in Medicine

AB - Purpose: To investigate the clinical implication of performing pre-treatment dosimetry for 90Y-microspheres liver radioembolization on 99mTc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Methods: Twenty-five patients treated with SIR-Spheres® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere® at Istituto Nazionale Tumori were considered. For each acquired 99mTc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL − T and HIL = IL − T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. Results: NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95% confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest %VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. Conclusions: The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. © 2018 American Association of Physicists in Medicine

KW - internal dosimetry accuracy

KW - liver radioembolization

KW - SPECT corrections

KW - SPECT quantification

KW - voxel dosimetry

KW - macrosalb tc 99m

KW - yttrium 90

KW - adult

KW - aged

KW - Article

KW - cancer radiotherapy

KW - clinical article

KW - comparative study

KW - controlled study

KW - dosimetry

KW - external beam radiotherapy

KW - female

KW - human

KW - image reconstruction

KW - liver cell carcinoma

KW - liver toxicity

KW - male

KW - radiation attenuation

KW - radiation dose distribution

KW - radioembolization

KW - reference value

KW - retrospective study

KW - single photon emission computed tomography

KW - three dimensional imaging

KW - treatment planning

KW - uncertainty

KW - artificial embolization

KW - calibration

KW - diagnostic imaging

KW - image processing

KW - imaging phantom

KW - liver

KW - liver tumor

KW - middle aged

KW - Monte Carlo method

KW - radiation response

KW - radiation scattering

KW - radiometry

KW - signal noise ratio

KW - Adult

KW - Calibration

KW - Embolization, Therapeutic

KW - Female

KW - Humans

KW - Image Processing, Computer-Assisted

KW - Liver

KW - Liver Neoplasms

KW - Male

KW - Middle Aged

KW - Monte Carlo Method

KW - Phantoms, Imaging

KW - Radiometry

KW - Retrospective Studies

KW - Scattering, Radiation

KW - Signal-To-Noise Ratio

KW - Technetium Tc 99m Aggregated Albumin

KW - Tomography, Emission-Computed, Single-Photon

KW - Uncertainty

U2 - 10.1002/mp.12774

DO - 10.1002/mp.12774

M3 - Article

VL - 45

SP - 1684

EP - 1698

JO - Medical Physics

JF - Medical Physics

SN - 0094-2405

IS - 4

ER -