Čerenkov radiation is a fascinating optical signal, which has been exploited for unique diagnostic biological sensing and imaging, with significantly expanded use just in the last half decade. Čerenkov Luminescence Imaging (CLI) has desirable capabilities for niche applications, using specially designed measurement systems that report on radiation distributions, radiotracer and nanoparticle concentrations, and are directly applied to procedures such as medicine assessment, endoscopy, surgery, quality assurance and dosimetry. When compared to the other imaging tools such as PET and SPECT, CLI can have the key advantage of lower cost, higher throughput and lower imaging time. CLI can also provide imaging and dosimetry information from both radioisotopes and linear accelerator irradiation. The relatively short range of optical photon transport in tissue means that direct Čerenkov luminescence imaging is restricted to small animals or near surface human use. Use of Čerenkov-excitation for additional molecular probes, is now emerging as a key tool for biosensing or radiosensitization. This review evaluates these new improvements in CLI for both medical value and biological insight. References and links 1. P. Čerenkov, "Visible radiation produced by electrons moving in a medium with velocities exceeding the of light," Phys. Rev. 52(4), 378-379 (1937). 2. P. Čerenkov, "Visible Emission of Člean Liquids by Action of $\gamma$ Radiation," Dokl. Akad. Nauk SSSR 2, 451-454 (1934). 3. R. H. Elrick and R. P. Parker, "The use of Cerenkov radiation in the measurement of beta-emitting radionuclides," Int. J. Appl. Radiat. Isot. 19(3), 263-271 (1968). 4. M. K. Johnson, "Counting of Čerenkov radiation from 32P in nonaqueous media," Anal. Biochem. 29(2), 348-350 (1969). 5. F. L. Hoch, R. A. Kuras, and J. D. Jones, "Iodine analysis of biological samples by neutron activation of 127-I, with scintillation counting of Čerenkov radiation," Anal. Biochem. 40(1), 86-94 (1971). 6. G. Bosia, C. Castagnoli, M. Dardo, and G. Marangoni, "Observation of structure in Čerenkov pulses from extensive air showers using fast techniques," Nature 225(5232), 532-533 (1970). 7. W. C. Haxton, "Salty water Čerenkov detectors for solar neutrinos," Phys. Rev. Lett. 76(10), 1562-1565 (1996). Chen, "PET and NIR optical imaging using self-illuminating (64)Cu-doped chelator-free gold nanoclusters," Biomaterials 35(37), 9868-9876 (2014). 72.

Biochemical and histological assays are currently used for the diagnosis and characterization of kidney injury. The purpose of this study was to compare technetium-99m-labeled dimercaptosuccinic acid (Tc-DMSA) renal scintigraphy, as a non-invasive method, with common biochemical and histopathological methods in two animal models of acute kidney injury. Nephrotoxicity was induced either by gentamicin (100 mg/kg/day for one week) or unilateral ureteral ligation (UUO). Renal scintigraphy was performed 1 h after intravenous injection of 99mTc-DMSA (3 mCi). Furthermore, plasma levels of blood urea nitrogen (BUN), creatinine, sodium, and potassium were determined using an autoanalyzer. At the end of experiments, kidneys were excised for the measurement of activity uptake (mCi/gr) using a dose calibrator as well as histopathological examinations with hematoxylin and eosin (H&E) staining. There was a significant decrease in 99mTc-DMSA uptake in both gentamicin (P value = 0.049) and UUO (P value = 0.034) groups, and it was more significant in the former. The levels of BUN and creatinine increased in both gentamicin and UUO groups, while the levels of sodium and potassium remained unchanged. Furthermore, a strong correlation was found between DMSA uptake and histopathological findings. Scintigraphy with 99mTc-DMSA is capable of detection of kidney injury in both gentamicin and UUO groups. Moreover, a significant correlation was found between scintigraphy parameters and histopathological findings. This suggests 99mTc-DMSA as a non-invasive method for the evaluation of kidney injury induced by drugs or anatomical disorders.

PurposePresence of photon attenuation severely challenges quantitative accuracy in single‐photon emission computed tomography (SPECT) imaging. Subsequently, various attenuation correction methods have been developed to compensate for this degradation. The present study aims to implement an attenuation correction method and then to evaluate quantification accuracy of attenuation correction in small‐animal SPECT imaging.MethodsImages were reconstructed using an iterative reconstruction method based on the maximum‐likelihood expectation maximization (MLEM) algorithm including resolution recovery. This was implemented in our designed dedicated small‐animal SPECT (HiReSPECT) system. For accurate quantification, the voxel values were converted to activity concentration via a calculated calibration factor. An attenuation correction algorithm was developed based on the first‐order Chang's method. Both phantom study and experimental measurements with four rats were used in order to validate the proposed method.ResultsThe phantom experiments showed that the error of −15.5% in the estimation of activity concentration in a uniform region was reduced to +5.1% when attenuation correction was applied. For in vivo studies, the average quantitative error of −22.8 ± 6.3% (ranging from −31.2% to −14.8%) in the uncorrected images was reduced to +3.5 ± 6.7% (ranging from −6.7 to +9.8%) after applying attenuation correction.ConclusionThe results indicate that the proposed attenuation correction algorithm based on the first‐order Chang's method, as implemented in our dedicated small‐animal SPECT system, significantly improves accuracy of the quantitative analysis as well as the absolute quantification.

AimsTo verify the accuracy of two common absorbed dose calculation algorithms in comparison to Monte Carlo (MC) simulation for the planning of the pituitary adenoma radiation treatment.Materials and methodsAfter validation of Linac's head modelling by MC in water phantom, it was verified in Rando phantom as a heterogeneous medium for pituitary gland irradiation. Then, equivalent tissue-air ratio (ETAR) and collapsed cone convolution (CCC) algorithms were compared for a conventional three small non-coplanar field technique. This technique uses 30 degree physical wedge and 18 MV photon beams.ResultsDose distribution findings showed significant difference between ETAR and CCC of delivered dose in pituitary irradiation. The differences between MC and dose calculation algorithms were 6.40 ± 3.44% for CCC and 10.36 ± 4.37% for ETAR. None of the algorithms could predict actual dose in air cavity areas in comparison to the MC method.ConclusionsDifference between calculation and true dose value affects radiation treatment outcome and normal tissue complication probability. It is of prime concern to select appropriate treatment planning system according to our clinical situation. It is further emphasised that MC can be the method of choice for clinical dose calculation algorithms verification.

No abstract

Purpose: The aim of the current attempt was quantitative investigation of the electromagnetic interference (EMI) of a mobile phone with the function of a SPECT gamma camera during data acquisition. Materials and Methods: We tested the effect of a mobile phone, in both ringing mode and standby mode, on one SPECT gamma camera during scanning a cylindrical phantom containing 5.4 mCi 99m Tc. The experiment was performed for different distances of 10,12,14, 16, 18, 20, 25, and 30 cm between mobile phone and head of the scanner, and for different head angles of 0, 30, 60, 90, 120, 150, and 180 degrees. A RF-EMF meter measured strength of electromagnetic field throughout the study. Statistically significant decrease in count number was considered to be electromagnetic interference. Results: There was significant reduction in the recorded counts during ringing of the mobile phone in all studied distances. For gamma camera, fixed at a distance, there was no uniform pattern of reduction of the counts at different angles between two operation modes of the mobile phone. Conclusions: A mobile phone, at close distance, can be a sensible source of electromagnetic field, disturbing the normal function of a gamma camera.Key Words: quantitative, electromagnetic interference, mobile phone, SPECT, gamma camera (Clin Nucl Med 2015;40: 545-547) E lectromagnetic interference (EMI) of mobile phones with the function of medical devices is an unfavorable event that may result in malfunctioning of this life-supporting equipment.1-6 Today, mobile phones have been translated from a just communication tool into can-not-live-without device, increasing the probability that it may come to the vulnerable medical devices.Although, up to now, number of reported significant medical errors that resulted from mobile phone interference with medical devices have been relatively rare, yet in the literature several cases of EMI and concomitant errors have been published. [7][8][9] Results of the studies have indicated that based on the factors such as type of medical device and mobile phone, and also separation distance between these two, different levels of EMI may occur.10 Gamma camera of a SPECT scanner is part of medical systems that may be susceptible to the electromagnetic field (EMF) generated by mobile phone. 7,11,12 SPECT is a routine imaging modality that provides images from bio-distribution of radioisotopes inside the body. The first clinical evidence of mobile phone EMI with SPECT scanner was a case report in which function of a gamma camera had been interrupted by ringing of a mobile phone, located in a patient's pocket, as light spots on frame 6 of the flow phase in the acquired image during the renal scintigraphy.7 This vulnerability is largely because of the photomultiplier tubes (PMTs) that are used to intensify acquired signal of the detected photons.13 Electromagnetic interference with the function of photomultiplier tubes, and consequently with the operation of gamma camera, dates back before the 1980s in which former models of SP...

No abstract

Purpose To determine the role of remote perconditioning (RPeC) on renal function and histology in an animal model of unilateral renal ischemia and reperfusion (IR) injury. Methods Rats were subjected to 60 min unilateral renal ischemia. RPeC protocol was the application of four cycles of 5 min IR of left femoral artery during renal ischemia. Assessments of histological changes and renal function were made 24 h, 1 week, or 3 weeks later. 99mTc-DMSA scan was performed using a small-animals SPECT system. Results 24-h reperfusion decreased the 99mTc-DMSA uptake in the left kidney compared to the intact kidney of control animals. RPeC group has higher uptake compared to the IR group. After 1 week and 3 weeks, uptakes were gradually increased in both groups and no differences were observed. Severe morphological changes in the ischemic kidneys of both groups were observed after 24 h which attenuated after 1 week and 3 weeks. Moreover, no differences in creatinine and BUN levels between IR-treated and intact animals were observed. Conclusion These data suggest that RPeC exerts a partially transient improvement in the renal function in the first day after reperfusion. However, long-term follow-up study showed no beneficial effects of RPeC. Moreover, noninvasive 99mTc-DMSA scan revealed a suitable tool in the follow-up evaluation of recovery process in the unilateral renal IR injury models.