Palmitoylethanolamide for the treatment of pain: pharmacokinetics, safety and efficacy

Palmitoylethanolamide (PEA) has been suggested to have useful analgesic properties and to be devoid of unwanted effects. Here, we have examined critically this contention, and discussed available data concerning the pharmacokinetics of PEA and its formulation. Sixteen clinical trials, six case reports/pilot studies and a meta‐analysis of PEA as an analgesic have been published in the literature. For treatment times up to 49 days, the current clinical data argue against serious adverse drug reactions (ADRs) at an incidence of 1/200 or greater. For treatment lasting more than 60 days, the number of patients is insufficient to rule out a frequency of ADRs of less than 1/100. The six published randomized clinical trials are of variable quality. Presentation of data without information on data spread and nonreporting of data at times other than the final measurement were among issues that were identified. Further, there are no head‐to‐head clinical comparisons of unmicronized vs. micronized formulations of PEA, and so evidence for superiority of one formulation over the other is currently lacking. Nevertheless, the available clinical data support the contention that PEA has analgesic actions and motivate further study of this compound, particularly with respect to head‐to‐head comparisons of unmicronized vs. micronized formulations of PEA and comparisons with currently recommended treatments.

Using a Virtual Tablet Machine to Improve Student Understanding of the Complex Processes Involved in Tablet Manufacturing

Objective. To develop and implement a virtual tablet machine simulation to aid distance students' understanding of the processes involved in tablet production. Design. A tablet simulation was created enabling students to study the effects different parameters have on the properties of the tablet. Once results were generated, students interpreted and explained them on the basis of current theory. Assessment. The simulation was evaluated using written questionnaires and focus group interviews. Students appreciated the exercise and considered it to be motivational. Students commented that they found the simulation, together with the online seminar and the writing of the report, was beneficial for their learning process. Conclusion. According to students' perceptions, the use of the tablet simulation contributed to their understanding of the compaction process.

SILICON PHOTOMULTIPLIERS FOR MEDICAL IMAGING AND DOSIMETRY-AN OVERVIEW

Silicon photomultipliers (SiPMs) are an enabling solid-state technology for low light sensing, with single photon sensitivity and photon number resolving capability. They feature an extremely high internal gain at the 10(6) level, comparable to photomultiplier tubes (PMTs), with the advantage of low operating voltage (~50 V compared to ~1000 V for PMT) and low energy consumption. The solid-state technology makes SiPMs compact, insensitive to magnetic fields and with an extreme flexibility in the design to cope with different applications. The fast development of the multiplication avalanche opens up the possibility to achieve time resolution at the 30 ps level. Dynamic range is however limited compared to PMT and the dark count rate relatively high, yet today at the level of 50 kHz/mm(2) at room temperature. Interfaced with scintillation material, SiPMs provide a powerful platform for medical imaging applications (in positron emission tomography/computed tomography and in positron emission tomography/magnetic resonance), for X-ray quality control as well as for novel compact radiation protection instruments. This article gives an overview of SiPMs for medical imaging and dosimetry. In addition, a learning and training program targeted to graduate students is described.

14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

The purpose of this study was to perform an initial investigation of the possibility to determine breast cancer growth rate with (14)C bomb-pulse dating. Tissues from 11 breast cancers, diagnosed in 1983, were retrieved from a regional biobank. The estimated average age of the majority of the samples overlapped the year of collection (1983) within 3σ Thus, this first study of tumour tissue has not yet demonstrated that (14)C bomb-pulse dating can obtain information on the growth of breast cancer. However, with further refinement, involving extraction of cell types and components, there is a possibility that fundamental knowledge of tumour biology might still be gained by the bomb-pulse technique. Additionally, δ (13)C and δ (15)N analyses were performed to obtain dietary and metabolic information, and to serve as a base for improvement of the age determination.

Spatial variability of the dose rate from (137)Cs fallout in settlements in Russia and Belarus more than two decades after the Chernobyl accident

Radionuclides from the 1986 Chernobyl accident were released and dispersed during a limited period of time, but under widely varying weather conditions. As a result, there was a high geographical variation in the deposited radioactive fallout per unit area over Europe, depending on the released composition of fission products and the weather during the 10 days of releases. If the plume from Chernobyl coincided with rain, then the radionuclides were unevenly distributed on the ground. However, large variations in the initial fallout also occurred locally or even on a meter scale. Over the ensuing years the initial deposition may have been altered further by different weathering processes or human activities such as agriculture, gardening, and decontamination measures. Using measurements taken more than two decades after the accident, we report on the inhomogeneous distribution of the ground deposition of the fission product (137)Cs and its influence on the dose rate 1 m above ground, on both large and small scales (10ths of km(2) - 1 m(2)), in the Gomel-Bryansk area close to the border between Belarus and Russia. The dose rate from the deposition was observed to vary by one order of magnitude depending on the size of the area considered, whether human processes were applied to the surface or not, and on location specific properties (e.g. radionuclide migration in soil).

Radiation Dose to Patients from Radiopharmaceuticals: a Compendium of Current Information Related to Frequently Used Substances

This report provides a compendium of current information relating to radiation dose to patients, including biokinetic models, biokinetic data, dose coefficients for organ and tissue absorbed doses, and effective dose for major radiopharmaceuticals based on the radiation protection guidance given in Publication 60(ICRP, 1991). These data were mainly compiled from Publications 53, 80, and 106(ICRP, 1987, 1998, 2008), and related amendments and corrections. This report also includes new information for 82Rb-chloride, iodide (123I, 124I, 125I, and 131I) and 123I labeled 2ß-carbomethoxy 3ß-(4-iodophenyl)-N-(3-fluoropropyl) nortropane (FPCIT).The coefficients tabulated in this publication will be superseded in due course by values calculated using new International Commission on Radiation Units and Measurements/International Commission on Radiological Protection adult and paediatric reference phantoms and Publication 103 methodology (ICRP,2007). The data presented in this report are intended for diagnostic nuclear medicine and not for therapeutic applications.

Review of radiation dose estimates in digital breast tomosynthesis relative to those in two-view full-field digital mammography

We examined how radiation dose levels in digital breast tomosynthesis (DBT) differ from those used in 2-view full-field digital mammography (FFDM). Acquisition parameter settings and information on the average absorbed dose to the glandular tissues within the breasts were reviewed based on clinical studies that evaluated DBT and FFDM. Dose ratios (DDBT/DFFDM) were derived from imaging protocols, which included tomosynthesis in 1- or 2-views alone, and as an adjunct technique to FFDM. Stand-alone DBT was associated with a much lower to a slightly higher radiation dose compared to that of comparable FFDM units, as summarized in dose ratio ranges of 0.34-1.0 for 1-view DBT, and 0.68-1.17 for 2-view DBT. One of the lowest reported dose estimates was obtained using a photon-counting DBT unit (avg. 0.70 mGy/scan; range: 0.28-1.26 mGy). Breast doses for DBT combined with FFDM are summarized in dose ratio ranges of 1.03-1.5 for 1-view DBT plus FFDM, and 2.0-2.23 for 2-view DBT plus FFDM. In the latter of these settings, the dose was reduced by ∼45% when 2D-views, reconstructed from the DBT images ("synthetic 2D images"), were used as a substitute for FFDM. Stand-alone DBT operated at lower to slightly higher radiation doses in comparison to FFDM. For DBT combined with FFDM, radiation doses were elevated, at maximum by a factor ∼2 1/4 of that of FFDM alone. In this setting, a replacement of FFDM with synthetic 2D-views reduced the breast dose approximately by half, which has substantial implications for population screening programs.

Chitosan in mucoadhesive drug delivery: focus on local vaginal therapy

Mucoadhesive drug therapy destined for localized drug treatment is gaining increasing importance in today's drug development. Chitosan, due to its known biodegradability, bioadhesiveness and excellent safety profile offers means to improve mucosal drug therapy. We have used chitosan as mucoadhesive polymer to develop liposomes able to ensure prolonged residence time at vaginal site. Two types of mucoadhesive liposomes, namely the chitosan-coated liposomes and chitosan-containing liposomes, where chitosan is both embedded and surface-available, were made of soy phosphatidylcholine with entrapped fluorescence markers of two molecular weights, FITC-dextran 4000 and 20,000, respectively. Both liposomal types were characterized for their size distribution, zeta potential, entrapment efficiency and the in vitro release profile, and compared to plain liposomes. The proof of chitosan being both surface-available as well as embedded into the liposomes in the chitosan-containing liposomes was found. The capability of the surface-available chitosan to interact with the model porcine mucin was confirmed for both chitosan-containing and chitosan-coated liposomes implying potential mucoadhesive behavior. Chitosan-containing liposomes were shown to be superior in respect to the simplicity of preparation, FITC-dextran load, mucoadhesiveness and in vitro release and are expected to ensure prolonged residence time on the vaginal mucosa providing localized sustained release of entrapped model substances.

An internal radiation dosimetry computer program, IDAC 2.0, for estimation of patient doses from radiopharmaceuticals

The internal dosimetry computer program internal dose assessment by computer (IDAC) for calculations of absorbed doses to organs and tissues as well as effective doses to patients from examinations with radiopharmaceuticals has been developed. The new version, IDAC2.0, incorporates the International Commission on Radiation Protection (ICRP)/ICRU computational adult male and female voxel phantoms and decay data from the ICRP publication 107. Instead of only 25 source and target regions, calculation can now be made with 63 source regions to 73 target regions. The major advantage of having the new phantom is that the calculations of the effective doses can be made with the latest tissue weighting factors of ICRP publication 103. IDAC2.0 uses the ICRP human alimentary tract (HAT) model for orally administrated activity and for excretion through the gastrointestinal tract and effective doses have been recalculated for radiopharmaceuticals that are orally administered. The results of the program are consistent with published data using the same specific absorption fractions and also compared with published data from the same computational phantoms but with segmentation of organs leading to another set of specific absorption fractions. The effective dose is recalculated for all the 34 radiopharmaceuticals that are administered orally and has been published by the ICRP. Using the new HAT model, new tissue weighting factors and the new adult computational voxel phantoms lead to an average effective dose of half of its earlier estimated value. The reduction mainly depends on electron transport simulations to walled organs and the transition from the stylised phantom with unrealistic interorgan distances to more realistic voxel phantoms.

A home-based weight lifting program for patients with arm lymphedema following breast cancer treatment: a pilot and feasibility study

It is well documented that resistance exercise can be performed by patients with breast cancer-related arm lymphedema. The aim of this pilot study was to evaluate the feasibility and safety of a 12-week self-administered weight lifting program for arm and shoulder, and its influence on arm lymphedema status, upper extremity muscle strength, and disability. Twenty-three patients with breast cancer-related arm lymphedema performed the program 3 times/week. The weight resistance levels were individually adjusted for shoulder flexion and adduction, and elbow extension and flexion corresponding to a repetition range of 8-12 repetition maximum. A log book was used to evaluate adherence to the program, wearing of compression sleeve and perceived exertion. Measurements were performed before a 2-week control period without intervention, and before and after intervention, and with arm volume measurements every fortnight to check for adverse events. Results revealed no significant changes during the control period. Adherence to the intervention program was excellent, and two adverse events were registered during the first weeks. After intervention, an increase of shoulder and arm strength (measured by an isometric muscle strength device) was found in all exercises (p = 0.001-0.003). A reduction of excess volume was shown, in ml (p = 0.03) and percentage (p = 0.005), measured by water displacement method. A tendency towards reduction (p = 0.07) of fat tissue in the upper arm (n = 10) in both arms was found measured by MRI. In this pilot study, we concluded that a home-based weight-lifting program performed by patients with breast cancer-related arm lymphedema is feasible and safe providing that the program includes regular follow-up for safety.

Detection of radioactive fragments in patients after radiological or nuclear emergencies using computed tomography and digital radiography

A comparison has been carried out between standard-dose computed tomography, non-diagnostic computed tomography and digital radiography with respect to their suitability for detecting radioactive fragments associated with nuclear or radiological events such as debris from radiological dispersal devices. The purpose was to investigate if radiographic imaging is justified for the detection and localisation of radioactive fragments in affected patients. Fragments of uranium (U), copper (Cu), iron (Fe) and volcanic ash with effective diameters ranging from (approximately) 100 to 700 μm were selected. The fragments were positioned at two different locations on an anatomical torso phantom and images were produced with standard-dose CT, non-diagnostic CT and digital radiography. Capsules with radionuclides of (137)Cs, (60)Co and (99m)Tc were also positioned in the phantom and the effective doses were estimated for radionuclide exposures as well as for standard-dose CT, non-diagnostic CT and digital radiography. For standard-dose CT and digital radiography, U, Cu and Fe fragments were detected in sizes down to 100-180, 250-300 and 300-400 μm respectively. For the non-diagnostic CT the results were 180-250 μm (for U), 300-400 μm (for Cu) and 400-500 μm (for Fe). The effective dose from the standard-dose CT, non-diagnostic CT and digital radiography was 5.6, 1.9 and 0.76 mSv. Corresponding doses from (137)Co, (60)Co and (99m)Tc positioned at the site of fragments were in the range of 0.07-0.1, 0.32-0.45 and 0.08-0.09 mSv per MBq during 24 h. We conclude that, for a number of gamma emitters with activity levels on the order of magnitude of megabecquerel, imaging using ionising radiation can be justified since the effective dose from the radionuclides will exceed the dose from the radiological examination.

Pectosomes and chitosomes as delivery systems for metronidazole: the one-pot preparation method

Mucoadhesive liposomes offer a potential for improved residence time of liposomal systems targeting contact with mucosal tissues, such as in buccal, oral, colon, and vaginal drug delivery. Most of the currently available methods rely on the coating of preformed liposomes by various mucoadhesive polymers. The aim of this study was to develop novel mucoadhesive system by the one-pot preparation method. The pectin- and chitosan-containing liposomes, namely pectosomes and chitosomes, were prepared by the modified solvent injection method. In order to optimize this novel delivery system, we used pectins and chitosans of both high and low degree of esterification/deacetylation (DE/DD), respectively. Sonication was applied to reduce the original vesicle size. All vesicles were characterized for their size, zeta potential, metronidazole entrapment, and stability. Both pectosomes and chitosomes were found to entrap more metronidazole than conventional plain liposomes. Preliminary data indicate that the polymer is present on the liposomal surface, embedded within inner liposomal bilayers, and entrapped inside the aqueous compartment. The next step in the evaluation of this system is the testing of its mucoadhesiveness.

ICRP perspective on criteria of acceptability for medical radiological equipment

The International Commission on Radiological Protection (ICRP) does not have a specific publication or recent detailed advice on acceptability criteria and suspension levels for medical radiological equipment. However, a number of the Commission's publications clearly stress the need to carry out acceptance testing of radiological equipment. Such general recommendations are frequent in earlier and recent reports related to external radiation therapy. Over 30 y ago, the ICRP even included some examples of parameter accuracies concerning acceptance levels in connection with radiotherapy units. Later more general advices related to acceptability tests as important parts of various quality assurance programs were formulated for radiation therapy as well as for radiodiagnostics without going into details to give values for specific parameters. In the radiodiagnostic field, there are such general recommendations in reports related to equipment for X-ray interventional procedures, digital radiology and computed tomography. The ICRP highly supports the elaboration of detailed and clear acceptability and suspension criteria for equipment used in medical radiology carried out by organisations like International Atomic Energy Agency, International Electrotechnical Commission, European Commission, National Electrical Manufacturers Association (NEMA, USA) and others and consider such criteria as important parts of the quality programmes to guarantee good radiation safety conditions for patients in radiation therapy as well as in radiodiagnostics.

Breast tomosynthesis and digital mammography: a comparison of diagnostic accuracy

OBJECTIVE

Our aim was to compare the ability of radiologists to detect breast cancers using one-view breast tomosynthesis (BT) and two-view digital mammography (DM) in an enriched population of diseased patients and benign and/or healthy patients.

METHODS

All participants gave informed consent. The BT and DM examinations were performed with about the same average glandular dose to the breast. The study population comprised patients with subtle signs of malignancy seen on DM and/or ultrasonography. Ground truth was established by pathology, needle biopsy and/or by 1-year follow-up by mammography, which retrospectively resulted in 89 diseased breasts (1 breast per patient) with 95 malignant lesions and 96 healthy or benign breasts. Two experienced radiologists, who were not participants in the study, determined the locations of the malignant lesions. Five radiologists, experienced in mammography, interpreted the cases independently in a free-response study. The data were analysed by the receiver operating characteristic (ROC) and jackknife alternative free-response ROC (JAFROC) methods, regarding both readers and cases as random effects.

RESULTS

The diagnostic accuracy of BT was significantly better than that of DM (JAFROC: p=0.0031, ROC: p=0.0415). The average sensitivity of BT was higher than that of DM (∼90% vs ∼79%; 95% confidence interval of difference: 0.036, 0.108) while the average false-positive fraction was not significantly different (95% confidence interval of difference: -0.117, 0.010).

CONCLUSION

The diagnostic accuracy of BT was superior to DM in an enriched population.

Evaluation of a sieve classification method for characterization of low-dose interactive mixtures

This study investigated a sieve classification method for evaluating carrier materials and particle size fractions, which could be a valuable tool in the early development of pharmaceutical dosage forms containing low-dose interactive mixtures. When developing new products based on interactive mixtures, it is essential to ensure that the drug particles are successfully deagglomerated and have adhered to the carrier particles. In this study, the effect on the demixing potential (DP) of low-dose interactive mixtures was assessed for various carrier particle sizes and surface textures. The model drug used was sodium salicylate and the tested carriers were lactose, mannitol, and isomalt. The results showed that the lowest DPs, i.e. the most mechanically stable mixtures, were obtained with lactose. Furthermore, for interactive mixtures, small carrier particles and/or a narrow carrier particle size range are essential for obtaining a low DP and high homogeneity. Calculation of the DP provided a reliable estimate of the quality of the low-dose interactive mixtures used in this study.

Visibility of microcalcification clusters and masses in breast tomosynthesis image volumes and digital mammography: a 4AFC human observer study

PURPOSE

To investigate the visibility of simulated lesions in digital breast tomosynthesis (BT) image volumes compared with 2D digital mammography (DM).

METHODS

Simulated lesions (masses and microcalcifications) were added to images of the same women acquired on a DM system (Mammomat Novation, Siemens) and a BT prototype. The same beam quality was used for the DM and BT acquisitions. The total absorbed dose resulting from a 25-projection BT acquisition and reconstruction (BT(25)) was approximately twice that of a single DM view. By excluding every other projection image from the reconstruction (BT(13)), approximately the same dose as in DM was effected. Simulated microcalcifications were digitally added with varying contrast to the DM and BT images. Simulated masses with 8 mm diameter were also added to BT images. A series of 4-alternative forced choice (4AFC) human observer experiments were conducted. Four medical physicists participated in all experiments, each consisting of 60 trials per experimental condition. The observers interpreted the BT image volumes in cine-mode at a fixed image sequence speed. The required threshold contrast (S(t)) to achieve a detectability index (d') of 2.5 (i.e., 92.5% correct decisions) was determined.

RESULTS

The S(t) for mass detection in DM was approximately a factor of 2 higher than required in BT indicating that the detection of masses was improved under BT conditions compared to DM. S(t) for microcalcification detection was higher for BT than for DM at both BT dose levels (BT(25) and BT(13)), with a statistically significant difference in S(t) between DM and BT(13). These results indicate a dose-dependent decrease in detection performance in BT for detection of microcalcifications.

CONCLUSIONS

In agreement with previous investigations, masses of size 8 mm can be detected with less contrast in BT than in DM indicating improved detection performance for BT. However, for the investigated microcalcifications, the results of this study indicate potentially worse performance for BT than for DM at the same dose level.

Measurements of long-term external and internal radiation exposure of inhabitants of some villages of the Bryansk region of Russia after the Chernobyl accident

A Nordic-Soviet programme was initiated in 1990 to evaluate the external and internal radiation exposure of the inhabitants of several villages in the Bryansk region of Russia. This area was one of the number of areas particularly affected by the nuclear accident at the Chernobyl Nuclear Power Plant in 1986. Measurements were carried out yearly until 1998 and after that more irregularly; in 2000, 2006 and 2008 respectively. The effective dose estimates were based on individual thermoluminescent dosemeters and on in vivo measurements of the whole body content of (137)Cs (and (134)Cs during the first years of the programme). The decrease in total effective dose during the almost 2 decade follow-up was due to a continuous decrease in the dominating external exposure and a less decreasing but highly variable exposure from internal irradiation. In 2008, the observed average effective dose (i.e. the sum of external and internal exposure) from Chernobyl (137)Cs to the residents was estimated to be 0.3mSv y(-1). This corresponds to 8% of the estimated annual dose in 1990 and to 1% of the estimated annual dose in 1986. As a mean for the population group and for the period of the present study (2006-2008), the average yearly effective dose from Chernobyl cesium was comparable to the absorbed dose obtained annually from external exposure to cosmic radiation plus internal exposure to naturally occurring radionuclides in the human body. Our data indicate that the effective dose from internal exposure is becoming increasingly important as the body burdens of Chernobyl (137)Cs are decreasing more slowly than the external exposure. However, over the years there have been large individual variations in both the external and internal effective doses, as well as differences between the villages investigated. These variations and differences are presented and discussed in this paper.

Breast cancer screening with tomosynthesis--initial experiences

Experiences gained so far using tomosynthesis for breast cancer screening will be reported. A short summary of results from preparatory studies will also be presented. The sensitivity and specificity of breast tomosynthesis (BT) will be compared with conventional two-dimensional digital mammography (DM) for breast cancer screening in a population-based study. Over 2000 women have been examined so far with BT and DM. The BT reading is significantly more time-consuming than the DM reading. Preparatory studies have shown that BT has a higher diagnostic precision and higher accuracy of size measurements and stage determination than DM. There is potential to use lower compression force with BT compared with DM, without decreasing the diagnostic accuracy. BT might play an important role in clinical as well as screening mammography. A large-scale population-based study to investigate BT as a screening modality is underway.

Using an optimised OSL single-aliquot regenerative-dose protocol for low-dose retrospective dosimetry on household salt

The single-aliquot regenerative-dose (SAR) protocols used in retrospective dosimetry for optically stimulated luminescence measurements have been mainly developed for archaeological and geological dating of quartz and feldspar. The aim in this study is to find a read-out protocol that can generate the most reproducible signal for household salt (NaCl) at absorbed doses below 100 mGy. The relation between the reproducibility of the signal, in terms of the ratio between given absorbed dose and SAR-calculated dose, and parameters such as test-dose pre-heat temperature has been studied. It was found that a temperature of 200 °C yielded the best reproducibility in the SAR-calculated dose, which is a somewhat higher pre-heat temperature than what is used for dating of quartz.

Minimising activity and dose with enhanced image quality by radiopharmaceutical administrations

Owing to the introduction of new diagnostic procedures, such as computed tomography (CT), positron emission tomography (PET) and single photon emission computed tomography (SPECT), the individual dose caused by medical exposures has grown rapidly in the last years. This is especially a subject to radiation protection for nuclear medical diagnosis, since in this case radiopharmaceuticals are administered to the patient, meaning not only a radiation exposure to the diseased tissue but also to the healthy tissues of large parts of the body. 'Minimizing Activity and Dose with Enhanced Image quality by Radiopharmaceutical Administrations' (MADEIRA) is a project cofunded by the European Commission within the Seventh Euratom Framework Programme that aims to improve three-dimensional (3D) nuclear medical imaging technologies significantly. MADEIRA is aiming to improve the efficacy and safety of 3D PET and SPECT functional imaging by optimising the spatial resolution and the signal-to-noise ratio, improving the knowledge of the temporal variation of the radiopharmaceuticals' uptake in and clearance from tumourous and healthy tissues, and evaluation of the corresponding patient dose. Using an optimised imaging procedure that improves the information gained per unit administered dose, MADEIRA aims especially to reduce the dose to healthy tissues of the patient. In this paper, an overall summary of the current achievements will be presented.

Microdosing for early biokinetic studies in humans

Microdosing is a new concept in drug development that--if implemented in the pharmaceutical industry--would mean that new drugs can be tested earlier in humans than done today. The human microdosing concept--or 'Phase 0'--may offer improved candidate selection, reduced failure rates in the drug development line and a reduction in the use of laboratory animals in early drug development, factors which will help to speed up drug development and also reduce the costs. Microdosing utilises sub-pharmacological amounts of the substance to open opportunities for early studies in man. Three technologies are used for microdosing: accelerator mass spectrometry (AMS), positron emission tomography and liquid chromatography-tandem mass spectrometry. This paper focuses on the principle of AMS and discusses the current status of microdosing with AMS.

Absolute quantification of activity content from PET images using the Philips Gemini TF PET/CT system

Positron emission tomography combined with computed tomography (PET/CT) is a quantitative technique suitable for diagnostics and uptake measurements. The quantitative results can be used for the purpose of the calculating absorbed dose to patients undergoing nuclear medicine investigations. Hence, the accuracy of the quantification of the activity content in organs or tissues is of great importance. When using a planar gamma camera and single photon emission computed tomography (SPECT) images, the activity content in organs and tumours has to be determined by the user, using the number of counts in the organs and the efficiency of the camera. However, when using a Philips Gemini TF PET/CT system, the activity concentration in a region of interest (ROI) is given by the system. The reliability of activity concentration values given by the Philips Gemini TF PET/CT system was studied using a Jaszczak phantom containing hot spheres of different sizes; the influence of the ROI size and the impact of organ size, that is the partial volume effect, was investigated with three different lesion-to-background ratios in the phantom. The use of a small ROI size (40 % of the large ROI size, which covered the entire sphere) showed a 15 % improvement in the recovery of the true activity. Small lesion sizes result in large underestimations of the activity concentration values.