3 research outputs found
Ultra-low dose whole-body CT for attenuation correction in a dual tracer PET/CT protocol for multiple myeloma
Purpose: To investigate within phantoms the minimum CT dose allowed for accurate attenuation correction of
PET data and to quantify the effective dose reduction when a CT for this purpose is incorporated in the clinical
setting.
Methods: The NEMA image quality phantom was scanned within a large parallelepiped container. Twenty-one
different CT images were acquired to correct attenuation of PET raw data. Radiation dose and image quality
were evaluated.
Thirty-one patients with proven multiple myeloma who underwent a dual tracer PET/CT scan were retrospec-
tively reviewed. 18F-fluorodeoxyglucose PET/CT included a diagnostic whole-body low dose CT (WBLDCT: 120
kV-80mAs) and 11C-Methionine PET/CT included a whole-body ultra-low dose CT (WBULDCT) for attenuation
correction (100 kV-40mAs). Effective dose and image quality were analysed.
Results: Only the two lowest radiation dose conditions (80 kV-20mAs and 80 kV-10mAs) produced artifacts in CT
images that degraded corrected PET images. For all the other conditions (CTDIvol ≥ 0.43 mGy), PET contrast
recovery coefficients varied less than ± 1.2%.
Patients received a median dose of 6.4 mSv from diagnostic CT and 2.1 mSv from the attenuation correction CT.
Despite the worse image quality of this CT, 94.8% of bone lesions were identifiable.
Conclusion: Phantom experiments showed that an ultra-low dose CT can be implemented in PET/CT procedures
without any noticeable degradation in the attenuation corrected PET scan. The replacement of the standard CT
for this ultra-low dose CT in clinical PET/CT scans involves a significant radiation dose reductio
Ultra-low dose whole-body CT for attenuation correction in a dual tracer PET/CT protocol for multiple myeloma
Purpose: To investigate within phantoms the minimum CT dose allowed for accurate attenuation correction of
PET data and to quantify the effective dose reduction when a CT for this purpose is incorporated in the clinical
setting.
Methods: The NEMA image quality phantom was scanned within a large parallelepiped container. Twenty-one
different CT images were acquired to correct attenuation of PET raw data. Radiation dose and image quality
were evaluated.
Thirty-one patients with proven multiple myeloma who underwent a dual tracer PET/CT scan were retrospec-
tively reviewed. 18F-fluorodeoxyglucose PET/CT included a diagnostic whole-body low dose CT (WBLDCT: 120
kV-80mAs) and 11C-Methionine PET/CT included a whole-body ultra-low dose CT (WBULDCT) for attenuation
correction (100 kV-40mAs). Effective dose and image quality were analysed.
Results: Only the two lowest radiation dose conditions (80 kV-20mAs and 80 kV-10mAs) produced artifacts in CT
images that degraded corrected PET images. For all the other conditions (CTDIvol ≥ 0.43 mGy), PET contrast
recovery coefficients varied less than ± 1.2%.
Patients received a median dose of 6.4 mSv from diagnostic CT and 2.1 mSv from the attenuation correction CT.
Despite the worse image quality of this CT, 94.8% of bone lesions were identifiable.
Conclusion: Phantom experiments showed that an ultra-low dose CT can be implemented in PET/CT procedures
without any noticeable degradation in the attenuation corrected PET scan. The replacement of the standard CT
for this ultra-low dose CT in clinical PET/CT scans involves a significant radiation dose reductio
3D voxel-based dosimetry to predict contralateral hypertrophy and an adequate future liver remnant after lobar radioembolization
Introduction Volume changes induced by selective internal radiation therapy (SIRT) may increase the possibility of tumor
resection in patients with insufficient future liver remnant (FLR). The aim was to identify dosimetric and clinical parameters
associated with contralateral hepatic hypertrophy after lobar/extended lobar SIRT with 90Y-resin microspheres.
Materials and methods Patients underwent 90Y PET/CT after lobar or extended lobar (right + segment IV) SIRT. 90Y voxel
dosimetry was retrospectively performed (PLANET Dose; DOSIsoft SA). Mean absorbed doses to tumoral/non-tumoral-treated
volumes (NTL) and dose-volume histograms were extracted. Clinical variables were collected. Patients were stratified by FLR at
baseline (T0-FLR): < 30% (would require hypertrophy) and ≥ 30%. Changes in volume of the treated, non-treated liver, and FLR
were calculated at < 2 (T1), 2–5 (T2), and 6–12 months (T3) post-SIRT. Univariable and multivariable regression analyses were
performed to identify predictors of atrophy, hypertrophy, and increase in FLR. The best cut-off value to predict an increase of
FLR to ≥ 40% was defined using ROC analysis.
Results Fifty-six patients were studied; most had primary liver tumors (71.4%), 40.4% had cirrhosis, and 39.3% had been
previously treated with chemotherapy. FLR in patients with T0-FLR < 30% increased progressively (T0: 25.2%; T1: 32.7%;
T2: 38.1%; T3: 44.7%). No dosimetric parameter predicted atrophy. Both NTL-Dmean and NTL-V30 (fraction of NTL exposed
to ≥ 30 Gy) were predictive of increase in FLR in patients with T0 FLR < 30%, the latter also in the total cohort of patients.
Hypertrophy was not significantly associated with tumor dose or tumor size. When ≥ 49% of NTL received ≥ 30 Gy, FLR
increased to ≥ 40% (accuracy: 76.4% in all patients and 80.95% in T0-FLR < 30% patients).
Conclusion NTL-Dmean and NTL exposed to ≥ 30 Gy (NTL-V30) were most significantly associated with increase in FLR
(particularly among patients with T0-FLR < 30%). When half of NTL received ≥ 30 Gy, FLR increased to ≥ 40%, with higher
accuracy among patients with T0-FLR < 30%