Diagnostic value of [99mTc]Tc-PSMA-I&S-SPECT/CT for the primary staging and restaging of prostate cancer.

Background: A large number of studies have proved that prostate-specific membrane antigen-positron emission tomography/computer tomography (PSMA-PET/CT) provides excellent accuracy in primary staging and restaging of prostate cancer. Less data exist with PSMA-single photon emission computed tomography (SPECT)/CT investigations. Objective: The aim of this study was to evaluate the performance of [99mTc]Tc-PSMA-I&S (for imaging and surgery) in prostate cancer. Design and methods: We retrospectively analysed PSMA-SPECT/CT scans of 20 healthy volunteers and 100 male patients with prostate cancer. All of them had histologically confirmed prostate cancer. In all, 28 patients were examined for primary staging and 72 for biochemical recurrence or progressive disease. Whole body SPECT/CT imaging was carried out 6 h after the intravenous administration of 666 ± 102 MBq [99mTc]Tc-PSMA-I&S. Images were evaluated visually and semi-quantitatively. Results: Patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy for primary prostate cancer were 86%, 100%, 100%, 83% and 92%, respectively. For detecting metastases in primary staging, these values were 88%, 100%, 100%, 85% and 93%, respectively. The radiopharmaceutical uptake of primary prostate cancer was significantly higher than in normal prostate. The patient-based sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the method in the visualization of local recurrence were 67%, 100%, 100%, 86% and 89%, and for detecting metastases in restaging were 91%, 92%, 98%, 75% and 91%, respectively. In restaging, detection rates were 37% under prostate-specific antigen level of 1 ng/mL, 74% between 1 and 5 ng/mL and 80% >5 ng/mL. Conclusion: [99mTc]Tc-PSMA-I&S-SPECT/CT can be easily integrated into the routine diagnostic practice, and it provides usable data in primary staging and restaging of prostate cancer. Quantitative assessment of PSMA-SPECT/CT has the potential to be used to differentiate between physiological and pathological intraprostatic tracer uptake.

Prostate-specific membrane antigen-based imaging for stereotactic irradiation of low-volume progressive prostate cancer: a single-center experience.

Introduction: Prostate-specific membrane antigen (PSMA) is a transmembrane protein that may be expressed on the surface of prostate cancer (PC) cells. It enables a more sensitive and specific diagnosis PC, compared to conventional anatomical imaging. Aim: The integration of PSMA-based imaging in the personalized radiotherapy of PC patients and the evaluation of its impact on target volume definition if stereotactic body radiotherapy (SBRT) is planned for locally recurrent or oligometastatic disease. Patients and methods: The data from 363 examinations were analyzed retrospectively. Inclusion criteria were histologically verified PC and clinical data suggesting local recurrence or distant metastasis. Whole-body 99mTc-PSMA-I&S single-photon emission computed tomography (SPECT)/CT or 18F-JK-PSMA-7 positron emission tomography/computer tomography (PET/CT) was carried out, and the evaluation of the scans and biological tumor volume contouring was performed at the Department of Nuclear Medicine. The target volume delineation on topometric CT (TCT) scan was performed at the Department of Oncotherapy. The comparison of the two volumes was performed by image fusion and registration. Results: From 363 PSMA isotope-based examinations, 84 lesions of 64 patients were treated with SBRT. In 50 patients, 70 lesions were examined for intermodality comparison. The target volume defined by the PSMA density was significantly smaller than the tumor size defined by the TCT scan: GTVCT (gross tumor volume on the TCT), 27.58 ± 46.07 cm3; BTVPSMA (biological target volume on the PSMA-based examination), 16.14 ± 29.87 cm3. During geometrical analyses, the Dice similarity coefficient (DSC) was 0.56 ± 0.20 (0.07-0.85). Prostate-specific antigen (PSA) control was performed to evaluate the response: mean pre-radiotherapy (pre-RT) PSA was 16.98 ng/ml ( ± SD: 33.81), and post-RT PSA at 3 months after SBRT was 11.19 ng/ml ( ± SD: 32.85). Three-month post-therapy PSMA-based imaging was performed in 14 cases, in which we observed a decrease or cessation of isotope uptake. Conventional imaging control was performed in 42 cases (65.6% of all cases): 22 (52.4%) complete remissions, 14 (33.3%) partial remissions, four (9.5%) stable diseases, and two (4.8%) progressive diseases were described. Conclusion: PSMA-based imaging is a promising diagnostic method for specifying the stage and detecting the low-volume progression. Our results suggest that PSMA-based hybrid imaging can influence treatment decisions and target volume delineation for SBRT.

Clinical considerations of bleomycin based electrochemotherapy with variable electrode geometry electrodes for inoperable, deep-seated soft tissue sarcomas.

The aim of the current prospective pilot study exclusively for deep-seated soft tissue sarcomas (STS) was to evaluate efficacy and safety of bleomycin-based ECT using VEG (variable electrode geometry) electrodes. During a 2-year period, seven surgically inoperable STSs were treated at the University of Szeged, Department of Surgery in Hungary. Electrode placement was determined by software planning using preoperative imaging (CT/MRI) and intraoperative ultrasound. Intravenous bleomycin (15.000 IU/m2) was administered 8 min before first pulse generation which lasted up to 40 min. Tumour response was evaluated through CT/MRI 2 months after treatment as per RECIST v.1.1. Five male- and 2 female patients were treated with fibromyxoid sarcoma (n = 2), epitheloid sarcoma (n = 3), liposarcoma (n = 1) and myofibroblastic sarcoma (n = 1) with median age of 54 years (49-88). Median tumour diameter, tumour volume and tumour depth was 5.9 cm (3.7-22.5), 131.13 cm3 (35.6-2456.22) and 6.18 cm (3.74-18.18), respectively. Median operative time was 75 min (35-180), median hospital stay 2 days (2-20). Two month follow-up confirmed partial response in 5 patients, while stable disease in 1 patient, and progressive disease in 1 case as per RECIST v.1.1. Grade 2 ulceration was experienced in four cases, and a transient left musculus quadriceps femoris plegia occured in one patient. Local control of deep-seated STSs with BLM-based VEG ECT holds a promising perspective and our results may serve as a practical guide for further investigation and treatment planning.

Comparison of Shear Wave Elastography and Dynamometer Test in Muscle Tissue Characterization for Potential Medical and Sport Application.

Skeletal muscle status and its dynamic follow up are of particular importance in the management of several diseases where weight and muscle mass loss and, consequently, immobilization occurs, as in cancer and its treatment, as well as in neurodegenerative disorders. But immobilization is not the direct result of body and muscle mass loss, but rather the loss of the maximal tension capabilities of the skeletal muscle. Therefore, the development of a non-invasive and real-time method which can measure muscle tension capabilities in immobile patients is highly anticipated. Our aim was to introduce and evaluate a special ultrasound measurement technique to estimate a maximal muscle tension characteristic which can be used in medicine and also in sports diagnostics. Therefore, we determined the relationship between the results of shear wave elastography measurements and the dynamometric data of individuals. The measurements were concluded on the m. vastus lateralis. Twelve healthy elite athletes took part in our preliminary proof of principle study-five endurance (S) and seven strength (F) athletes showing unambiguously different muscle composition features, nine healthy subjects (H) without prior sports background, and four cancer patients in treatment for a stage 3 brain tumor (T). Results showed a high correlation between the maximal dynamometric isometric torque (Mmax) and mean elasticity value (E) for the non-athletes [(H + T), (r = 0.795)] and for the athletes [(S + F), (r = 0.79)]. For the athletes (S + F), the rate of tension development at contraction (RTDk) and E correlation was also determined (r = 0.84, p < 0.05). Our measurements showed significantly greater E values for the strength athletes with fast muscle fiber dominance than endurance athletes with slow muscle fiber dominance (p < 0.05). Our findings suggest that shear wave ultrasound elastography is a promising method for estimating maximal muscle tension and, also, the human skeletal muscle fiber ratio. These results warrant further investigations with a larger number of individuals, both in medicine and in sports science.

Radiation Dosimetry of 99mTc-PSMA I&S: A Single-Center Prospective Study.

99mTc-PSMA I&S is a prostate-specific membrane antigen (PSMA) tracer that can be used for planar and SPECT/CT γ-imaging and radioguided surgery. The primary aim of this study was to estimate the dosimetry of 99mTc-PSMA I&S using a hybrid method (sequential γ-planar imaging and 1 single SPECT/CT) in healthy volunteers. The secondary aim was to depict the tracer biodistribution and tumor-to-background ratios (TBRs) in patients with prostate cancer (PCa). Methods: Dosimetry of 99mTc-PSMA I&S was investigated in 4 healthy volunteers. Whole-body planar imaging was acquired at 1, 2, 3, 6, and 24 h and SPECT/CT at 6 h after tracer injection. Contours of organs were drawn on all acquisitions to determine organ activity at each time point. Absorbed dose was estimated using 2 methods: independent curve-fitting manual method (Levenberg-Marquardt-based algorithm using dose factors from RAdiation Dose Assessment Resource [RADAR] website) and OLINDA/EXM software (version 2.0; HERMES Medical Solutions). Biodistribution of 99mTc-PSMA I&S was assessed in 10 patients with PCa on SPECT/CT images at 6 h. Tumor uptake (SUVmax), and TBR (tumor SUVmax/background organ SUVmean) using muscle (T/M), bladder (T/B), and intestine (T/I) as background organs were determined. Results: The mean injected activity of 99mTc-PSMA I&S was 717 MBq (range: 562-828 MBq). No adverse events related to the injection of 99mTc-PSMA I&S were reported. The average radiation effective dose was 0.0055 mSv/MBq with the RADAR manual method and 0.0052 mSv/MBq with OLINDA/EXM. Total body effective dose ranged between 3.33-4.42 and 3.11-4.23 mSv, respectively. All PCa patients showed high tracer uptake in primary and metastatic lesions with T/M, T/B, and T/I ranging from 5.29-110, 0.11-7.02, and 0.96-16.30, respectively. Conclusion: Effective doses of 99mTc-PSMA I&S were comparable to those known for most of the 99mTc tracers and was lower than for the 68Ga-labeled and 18F-labeled agents. 99mTc-PSMA I&S SPECT/CT showed high TBR in PCa patients. This study can provide required data for translation and approval of 99mTc-PSMA I&S by regulatory agencies.

Management of cardiac implantable electronic device infection using a complete interdisciplinary approach.

Technological advances and increasing operator experience have improved the success rate of transvenous lead extraction (TLE). However, in some cases-especially with longer lead dwelling time-TLE can be highly complicated. In this case report, the authors present an unusual case of implantable cardioverter defibrillator (ICD) pocket infection diagnosed by 18F­fluorodeoxyglucose positron emission tomography/computed tomography (18F­FDG-PET/CT). Complete lead extraction required a combined transvenous and surgical approach. Contralateral reimplantation failed due to occlusion of the right brachiocephalic vein. Therefore, a subcutaneous ICD was implanted. This case highlights the importance of an interdisciplinary approach to the treatment of cardiac implantable electronic device infection.

New Treatment Option for Capillary Lymphangioma: Bleomycin-Based Electrochemotherapy of an Infant.

The treatment of microcystic and combined lymphangiomas, especially in the head and neck region, is still a challenge because the lymphangiomas do not respond to conventional therapies and their recurrence rate is high, regardless of the treatment choice. Complete surgical resection is the main treatment of lymphangiomas, but because of localization perioperative complications, such as bleeding, neural damage and airway obstruction are common disadvantages of this method. Bleomycin-based sclerotherapy is another common therapeutic approach, in which the lymphocysts are aspirated, and 25% to 50% of their volumes are replaced with a sclerotisant drug. This is an effective treatment in cases in which the vessels are large enough for an intravascular or intracystic injection, but because of the small size of vessels and cysts, the microcystic and combined lymphangiomas are not suitable for sclerotherapy. Delivery of drugs for treating sclerosis to endothelial cells can be achieved by electroporation (electrochemotherapy), even for capillary malformations. A congenital, rapidly growing combined lymphangioma of the left cervicofacial region was treated with one session of bleomycin-based electrochemotherapy. Seven months after treatment, the growth-corrected target volume decrease was 63% and the dislocation of the trachea and blood vessels previously observed had ceased. We suggest that bleomycin-based electrochemotherapy is a feasible alternative treatment option for capillary malformations.

[Theranostics in 2020: Neuroendocrine tumors]. / Teranosztikumok 2020-ban: Neuroendokrin tumorok.

This article presents the diagnostic and therapeutic nuclear medicine methods for neuroendocrine tumors in accordance with current guidelines. The paper begins with a general characterization of neuroendocrine tumors, followed by a broad introduction to laboratory and imaging diagnostic techniques, and a detailed discussion of peptide receptor radionuclide therapy and meta-iodobenzylguanidine treatment. Finally, the article provides an insight into current research and future developments.

18F-FDG-PET/CT in the evaluation and differential diagnosis of active large-vessel vasculitis. A prospective study. / [18F-FDG-PET/CT-vel szerzett tapasztalataink az aktív nagyérvasculitisek diagnosztikájában és differenciáldiagnózisában. Prospektív vizsgálat.]

Introduction: Large-vessel vasculitis has non-specific clinical symptoms, which can delay the diagnosis. Early recognition and treatment of the disease can help to avoid late complications. 18 F-FDG-PET can detect the inflammation of the vessel wall in the early stage of the disease with high sensitivity. CT is used to localize vasculitis. Aim: To examine the performance of 18F-FDG-PET/CT in patients with suspected large-vessel vasculitis, during relapse and remission, focusing on disease activity and extent. Method: 43 patients were evaluated. They were classified according to the clinical questions: steroid-naive suspected vasculitis, suspected vasculitis on steroid treatment, patients with relapse and in remission. We examined 10 cancer patients in control. We carried out visual and quantitative analysis of the 18F-FDG uptake of vessel walls. During quantitative evaluation, we determined standardised uptake values (SUVmax) of vessel wall segments compared to liver. Results: We found active disease in 5 patients examined for primary diagnosis, moreover, in 5 patients with relapse. The disease involved 3 or more vessel segments in fifty percent of the active cases. In the visually active group, the SUVmax was significantly lower in patients on steroid treatment than in steroid-naive cases (1.17 ± 0.11 vs. 1.43 ± 0.29; p = 0.005). We confirmed remission in 2 cases after therapy. In the inactive group, we found other types of inflammatory disorders in 8 cases. Conclusion: 18F-FDG-PET/CT is an effective diagnostic tool for large-vessel vasculitis, and can be used to determine the activity and extent of the disease. Steroid treatment influences the 18F-FDG-uptake of vessel wall. Orv Hetil. 2020; 161(20): 829-838.

[18F-fluoro-deoxy-glucose positron emission tomography/computer tomography (18F-FDG-PET/CT) imaging in cardiology]. / 18F-fluoro-dezoxi-glükóz pozitronemissziós tomográfia/komputertomográfia (18F-FDG-PET/CT) képalkotás a kardiológiában.

Over the past decades, 18F-FDG-PET/CT imaging has been recognized as an indispensable tool in the diagnosis, staging and treatment monitoring of cancer. This modern imaging technique combining functional and morphologic information has approved indications not only in oncology but in clinical cardiology as well. In the current review we discuss the specific requirements of patient preparation and image acquisition protocol for cardiac 18F-FDG-PET/CT. We review the literature in some cases highlighted by our own examinations of well-known "gold standard" viability and onco-cardiology examinations while placing special emphasis on inflammatory disorders involving the heart. This relatively newer class of indications includes prosthetic valve endocarditis, cardiac implantable device infection, myocardial inflammation of varying origin such as sarcoidosis where 18F-FDG-PET/CT appears to be particularly useful in the differential diagnosis of cases where standard investigation is non-diagnostic or equivocal. Orv Hetil. 2019; 160(26): 1015-1024.

Efficacy and safety of long pulse 1064 and 2940 nm lasers in noninvasive lipolysis and skin tightening.

Noninvasive body shaping is becoming a growing demand. The aim of this study was to investigate the efficacy and safety of the combined treatments of 1064 nm Nd:YAG and 2940 nm Er:YAG in noninvasive lipolysis and skin tightening. Ten females were enrolled, and all women's side of the waist or the lower part of the abdomen were treated. In the first step, the 1064 nm Nd:YAG was used. As a second step, the 2940 nm Er:YAG laser was applied. Each woman was treated four times, once every 2 weeks. The effects were determined by comparative photo documentation, waist circumference measurement, two-dimensional B-mode ultrasonography and low-dose native computer tomography (CT), whereas body fat was monitored with bioelectric impedance. The tissue firmness was measured by ultrasound shear wave elastography. Combined laser treatment significantly reduced waist circumference and total body fat. Ultrasonography has revealed that the treatment considerably decreased fat thickness and improved skin stiffness in the treated region. Subcutaneous fat volume, measured by low-dose CT, displayed a moderate decrease in the waist region. The combined 1064 nm Nd:YAG and 2940 nm Er:YAG laser treatment results in the reduction of fat tissue and tightens the skin as confirmed by objective measurements.

Detection of myocardial inflammation by 18F-FDG-PET/CT in patients with systemic sclerosis without cardiac symptoms: a pilot study.

OBJECTIVES: Primary cardiac manifestation is a common complication of systemic sclerosis (SSc) with poor prognosis. The aim of the current study was to detect potential myocardial inflammation present in asymptomatic SSc patients by 18F-FDG-PET/CT and to investigate its relationship with early signs of myocardial dysfunction as detected by 2D speckle tracking echocardiography (2DSTE). METHODS: Sixteen consecutive patients with SSc and 9 control patients without clinical evidence of cardiac involvement were enrolled in the study. On 18F-FDG-PET acquired images blood-pool normalised SUV ratio and heterogenity index (HI: standard deviation of SUV divided with mean SUV) were calculated. Within 24 hours all SSc patients underwent 2DSTE strain analysis. RESULTS: Eight of 16 SSc patients were found to be visually PET-positive and showed significantly higher myocardial 18F-FDG SUV ratio (1.78±0.74 vs. 0.98±0.03; p<0.05) and heterogenity index (0.13±0.02 vs. 0.05±0.02; p<0.001) as compared to the control group. FDG-PET/CT derived values did not differ significantly between visually PET-negative (8/16) and control patients (SUV ratio: 0.98±0.05 vs. 0.98±0.03; HI: 0.05±0.01 vs. 0.05±0.02). Global left ventricular longitudinal strain values did not differ significantly between PET-positive and negative patients (17.18±3.49% vs. 17.59±3.65%). CONCLUSIONS: Myocardial inflammation, as a potential sign of early cardiac involvement can be detected by 18-FDG-PET/CT in a considerable percentage of systemic sclerosis patients presenting without cardiac symptoms.

[Initial experiences with 99mTc-PSMA-SPECT/CT in patients with prostate cancer]. / Kezdeti tapasztalatok a 99mTc-PSMA-SPECT/CT-vel prosztatarákos betegekben.

INTRODUCTION: The prostate-specific membrane antigen (PSMA) is a transmembrane protein, that is highly expressed on the surface of prostate cancer cells. In the last few years, several PSMA-specific ligands have been developed, that can be successfully used to detect primary prostate cancer, tumor recurrences and metastases as well. AIM: The goal of our work was to examine the clinical application of a 99mtechnetium-labeled PSMA-radiopharmaceutical as part of the routine diagnostics of prostate cancer. METHOD: We examined 15 male patients with verified prostate adenocarcinoma with suspicion of progression or recurrence of the disease. We performed whole-body PSMA-SPECT/CTs and multiparametric MRIs of the prostate and the pelvic regions within a week. We used 99mTc-mas3-y-nal-k(Sub-KuE) for the PSMA-SPECT scans. The images were visually evaluated by independent observers. The results were compared with the follow-up bone scintigraphies as well. RESULTS: Twenty-two PSMA-positive lesions were found. Nine of them were localized outside, 13 were within the MRI's field of view. From these 13 lesions, 7 matched with the SPECT/CT results and in 5 cases the MRI images showed no abnormalities. In one case, bone metastasis was suspected on the MRI scan but there was no corresponding pathological tracer uptake on the SPECT images. In two patients, none of the examinations showed signs of prostate malignancy. Four patients had PSMA-positive bone metastases. One of them had a matching PSMA/SPECT and bone scintigraphy result and in one case the PSMA examination showed metastasis in contrast to the negative bone scintigraphy. CONCLUSION: PSMA-SPECT/CT with 99mTc-mas3-y-nal-k(Sub-KuE) is a promising diagnostic tool. This technique is capable of visualizing bone metastases and it can detect local recurrences and visceral metastases as well. Orv Hetil. 2018; 159(35): 1433-1440.

Primary cardiac angiosarcoma: A case report.

Cardiac angiosarcomas are the most common primary malignant cardiac tumors in adults. The diagnosis is often delayed due to nonspecific clinical symptoms at presentation. The cornerstones of diagnosis are echocardiography and the histological evaluation of the cardiac biopsy. The knowledge on the treatment is limited; the outcomes of chemotherapy, radiotherapy, complete surgical removal, and heart transplantation are controversial. We report a 38-year-old woman with a primary heart tumor which infiltrated the right atrial wall and the pericardium and caused pericardial effusion. Angiosarcoma was verified histologically. The surgical excision could not be radical, and the patient died 3 months from diagnosis.

[Nuclear medicine in oncotherapy]. / Nukleáris medicina az onkoterápiában.

After a brief historical overview, the basic concept of therapy with radionuclides is summarised. This is followed by a review of the physical and biological features of the different radiopharmaceuticals that are available. A clinical application of the different techniques commences with the treatment of differentiated thyroid cancer using radio-iodine. From the various bone-seeking radiopharmceuticals, we opted for the alpha-emitting 223-RaCl2 for treatment purposes. Due to the increasing prevalence of neuroendocrine tumors nowadays, somatostatin receptor and adrenerg analog radiotherapy are discussed. Next, one of the most promising new techniques is presented along with some radioimmunological applications. Lastly, the importance of multidisciplinary cooperation is analysed from the viewpoint of successful individual oncotherapy and safe radionuclide treatment for the benefit of patients.

[Role of 18FDG-PET/CT in the management and gross tumor volume definition for radiotherapy of head and neck cancer; single institution experiences based on long-term follow-up]. / 18FDG-PET/CT szerepe fej-nyak daganatok kezelésében és a sugárterápiás tumortérfogat meghatározásában - Az SZTE Onkoterápiás Klinika eredményeinek értékelése.

The purpose of our work is evaluation of the impact of 18FDG-PET/CT on the complex management of locoregionally advanced (T3-4N1-3) head and neck squamous cell cancer (LAHNSC), and on the target definition for 3D conformal (3DCRT) and intensity-modulated radiotherapy (IMRT). 18FDG-PET/CT were performed on 185 patients with LAHNSC prior to radiotherapy/chemoradiation in the treatment position between 2006 and 2011. Prior to it 91 patients received induction chemotherapy (in 20 cases of these, baseline PET/CT was also available). The independently delineated CT-based gross tumor volume (GTVct) and PET/CT based ones (GTVpet) were compared. Impact of PET/CT on the treatment strategy, on tumor response evaluation to ICT, on GTV definition furthermore on overall and disease-specific survival (OS, DSS) was analysed. PET/CT revealed 10 head and neck, 2 lung cancers for 15 patients with carcinoma of unknown primary (CUP) while 3 remained unknown. Second tumors were detected in 8 (4.4%), distant metastasis in 15 (8.2%) cases. The difference between GTVct and GTVpet was significant (p=0.001). In 16 patients (14%) the GTVpet were larger than GTVct due to multifocal manifestations in the laryngo-pharyngeal regions (4 cases) or lymph node metastases (12 cases). In the majority of the cases (82 pts, 72%) PET/CT-based conturing resulted in remarkable decrease in the volume (15-20%: 4 cases, 20-50%: 46 cases, >50%: 32 cases). On the basis of the initial and post-ICT PET/CT comparison in 15/20 patients more than 50% volume reduction and in 6/20 cases complete response were achieved. After an average of 6.4 years of follow-up the OS (median: 18.3±2.6 months) and DSS (median: 25.0±4.0 months) exhibited close correlation (p=0.0001) to the GTVpet. In cases with GTVpet <10 cm3 prior to RT, DSS did not reach the median, the mean is 82.1±6.1 months, while in cases with GTVpet 10-40 cm3 the median of the DSS was 28.8±4.9 months (HR = 3.57; 95% CI: 1.5-8.3), and in those with GTVpet >40 cm3 the median DSS was 8.4±0.96 months (HR= 11.48; 95% CI: 5.3-24.9). Our results suggest that 18FDG-PET/CT plays an important role for patient with LAHNSC, by modifying the treatment concept and improving the target definition for selective RT modalities. Volumetric PET/CT-based assessment of the tumor response after ICT gives valuable contribution to further therapy planning.

Validation of CT doses of SPECT/CT and PET/CT hybrid devices: lessons learned.

The aim of the study was to check the validity of computed tomographic (CT) doses exhibited by SPECT/CT and PET/CT hybrid devices. Dose measurements were taken from four SPECT/CT and four PET/CT cameras commercially available from different manufacturers. A calibrated ionization chamber was placed in whole-body or head phantoms for the acquisition of CT images with clinically used parameters. Computed tomography dose index (CTDIvol) values were calculated according to the IEC 60601-2-44:1999 formula. The measured CTDIvol doses were compared with those preprogrammed by the manufacturer. In the case of the whole-body phantom, the differences between the measured and displayed values varied between -31 and +24% [European document RP162 (2012) sets up the limit for acceptance criterion as ±20%]. The head phantom data showed either an agreement between -10 and +24%, or an underestimation by two-fold. The latter seemed to be because, while preprogramming the doses, the manufacturer had used the whole-body phantom instead of a proper head phantom. The results of the work demonstrate the need for individual dosimetric calibration of every single X-ray tube. Dosimetric checks should be included in the regular quality control programmes of the SPECT/CT and PET/CT devices. Special attention should be paid to head-and-neck and paediatric protocols, in which the use of a head phantom is recommended for dose calibration.