Reduction of EpCAM-Positive Cells from a Cell Salvage Product Is Achieved by Leucocyte Depletion Filters Alone

Intraoperative cell salvage reduces the need for allogeneic blood transfusion in complex cancer surgery, but concerns about the possibility of it re-infusing cancer cells have hindered its application in oncology. We monitored the presence of cancer cells on patient-salvaged blood by means of flow cytometry; next, we simulated cell salvage, followed by leucodepletion and irradiation on blood contaminated with a known amount of EpCAM-expressing cancer cells, assessing also residual cancer cell proliferation as well as the quality of salvaged red blood cell concentrates (RBCs). We observed a significant reduction of EpCAM-positive cells in both cancer patients and contaminated blood, which was comparable to the negative control after leucodepletion. The washing, leucodepletion and leucodepletion plus irradiation steps of cell salvage were shown to preserve the quality of RBCs in terms of haemolysis, membrane integrity and osmotic resistance. Finally, cancer cells isolated from salvaged blood lose their ability to proliferate. Our results confirm that cell salvage does not concentrate proliferating cancer cells, and that leucodepletion allows for the reduction of residual nucleated cells, making irradiation unnecessary. Our study gathers pieces of evidence on the feasibility of this procedure in complex cancer surgery. Nevertheless, it highlights the necessity of finding a definitive consensus through prospective trials.

How direct measurements of worker eyes with a Scheimpflug camera can affect lensdose coefficients in interventional radiology

The 2013/59/Euratom Directive reduced the occupational exposure limits for the lens. Since it has become crucial to estimate the dose absorbed by the lens, we have studied the individual variability of exposed workers' ocular conformations with respect to the data estimated from their personal dosimetry. The anterior eye conformations of 45 exposed workers were acquired using Scheimpflug imaging and classified according to their sight conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario using Monte Carlo code. The models were dosimetrically analysed by simulating setup A, a theoretical monoenergetic and isotropic photon source (10-150 keV) and setup B, a more realistic interventional setting with an angiographic x-ray unit (50, 75, 100 kV peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1-10.1) mm. Using these data for model reconstruction, dose coefficients (DCs) were simulated for all ocular structures. Regardless of the eye model used, the DCs showed a similar trend with radiation energy, which highlighted that for the same energy and setup, no significant dependence on ocular morphology and workers' visual conditions was observed. The maximum difference obtained did not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction, compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the dose absorbed by the other eye structures, it is, instead, essential to know the spectrum of the source that has generated the irradiation, since there are differences between monoenergetic sources and more realistic angiographic units.

DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation

The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation.

CT protocol optimisation in PET/CT: a systematic review

Purpose

Currently, no consistent guidelines for CT scans used within PET/CT examinations are available. This systematic review provides an up-to-date overview of studies to answer the following questions: What are the specific CT protocols used in PET/CT? What are the possible purposes of requiring a CT study within a PET/CT scan? Is the CT protocol obtained from a dosimetric optimisation study?

Materials and method

PubMed/MEDLINE, Cochrane Library, Embase and Scopus were systematically searched for relevant studies in accordance with the PRISMA statement. The literature search was conducted from January 2007 until June 2019. Data derived from studies were standardized in order to reduce possible biases, and they were divided into clinically homogeneous subgroups (adult, child or phantom). Subsequently, we divided the CT protocol intents into 3 types (anatomic localization only, attenuation correction only and diagnostic purpose). A narrative approach was used to summarise datasets and to investigate their heterogeneity (due to medical prescription methodology) and their combination in multiseries CT protocols. When weighted computed tomography dose index (CTDI_w) was available, we calculated the volumetric computed tomography dose index (CTDI_vol) using the pitch value to make the results uniform. Eventually, the correlation between protocol intents and CTDI_vol values was obtained using a Kruskal–Wallis one-way ANOVA statistical test.

Result

Starting from a total of 1440 retrieved records, twenty-four studies were eligible for inclusion in addition to two large multicentric works that we used to compare the results. We analyzed 87 CT protocols. There was a considerable range of variation in the acquisition parameters: tube current–time product revealed to have the most variable range, which was 10–300 mAs for adults and 10–80 mAs for paediatric patients. Seventy percent of datasets presented scans acquired with tube current modulation, 9% used fixed tube current and in 21% of them, this information was not available. Dependence between mean CTDI_vol values and protocol intent was statistically significant (p = 0.002). As expected, in diagnostic protocols, there was a statistically significant difference between CTDI_vol values of with and without contrast acquisitions (11.68 mGy vs 7.99 mGy, p = 0.009). In 13 out of 87 studies, the optimisation aim was not reported; in 2 papers, a clinical protocol was used; and in 11 works, a dose optimisation protocol was applied.

Conclusions

According to this review, the dose optimisation in PET/CT exams depends heavily on the correct implementation of the CT protocol. In addition to this, considering the latest technology advances (i.e. iterative algorithms development), we suggest a periodic quality control audit to stay updated on new clinical utility modalities and to achieve a shared standardisation of clinical protocols. In conclusion, this study pointed out the necessity to better identify the specific CT protocol use within PET/CT scans, taking into account the continuous development of new technologies.

Attenuation assessment of medical protective eyewear: the AVEN experience

The goal of this paper is to test the attenuation capability of seven models of protective eyewear used in routine clinical practice. Scattered radiation from a standard patient was simulated by using a water tank located over the treatment couch of a GE Innova 3100 x-ray angiography system. Seven protective eyewear models were tested using an anthropomorphic phantom mimicking the first operator. At each test, 4 thermoluminiscent dosimeters were placed on the phantom (respectively in front of the protective eyewear, under the eyewear, on the left earpiece and at chest level) in order to have an eyewear-independent reference. A test session without glasses was also acquired. Each model was tested with standard posterior-anterior (PA) projections and the two most common protective eyewear were tested using LAO90° and LAO45°CRA30° projections. A worst-case scenario was created to be sure of having an upper limit for the assessment of eyewear attenuation in routine clinical practice. In PA projections, the absolute attenuation value ranged between 71% and 81%, while relative attenuation between dose measured at eye lens and that measured at eyewear earpiece ranged from 67% to 85%. The slightly wider range was probably due to scatter radiation variability; anyway, differences are still included in the variable uncertainty of experimental measurements. It is worth noting that #3 eyewear model (the one without lateral protection) allows an attenuation similar to that of #5 eyewear model (with 0.5 mm lead lateral protection) in LAO90° and LAO45°CRA30° projections. Despite the experimental limitations, a description of the radiation properties of protective eyewear concerning radiation attenuation can be useful to rely on protection devices which can be used in routine clinical practice.

Radiation protection procedures in 131I treatments for thyroid cancer in patients requiring hemodialysis

BACKGROUND

Hemodialysis is essential for patients with renal failure, and iodine-131 ((131)I) administration is the standard of care in thyroid carcinoma treatment. Although the need for hemodialysis during (131)I treatment is very rare, it raises some concerns due to the involvement of personnel not exposed to radiation and to the contamination of devices used for other patients. In this paper, a radioprotection protocol to perform hemodialysis safely on patients during (131)I treatment has been presented.

PATIENTS AND METHODS

The exposure of personnel who assisted 13 patients over the course of 10 years was monitored: external exposure was measured through electronic dosimeters, and internal contamination was checked by thyroid uptake and urine sample gamma spectrometry. Over this period, room layout was optimized to allow an improvement of radioprotection procedures.Two nurses were involved in patient assistance.

RESULTS

After hemodialysis, measurements of internal contamination were below the minimum detectable activity and external exposure was in the range of 1-82 μSv in terms of H(p)(10). A reduction in personnel exposure was observed after hospitalization room renovation: H(p)(10) normalized to the activity administered to the patient was about halved.

CONCLUSION

The data show that hemodialysis can be performed safely during I treatments when appropriate radioprotection actions are implemented.

Comparison of two different types of LiF:Mg,Cu,P thermoluminescent dosimeters for detection of beta rays (beta-TLDs) from 90Sr/90Y, 85Kr and 147Pm sources

Targeted radionuclide therapies in nuclear medicine departments increasingly depend on using unsealed beta radiation sources in the labeling of peptides and antibodies. Monitoring doses received by the fingers and hands during these procedures is best accomplished with TLD dosimeters that can be located at the fingertips. The present study examines the response of two TLD dosimeters (MCP-Ns and GR200A) to 90Sr/90Y, 85Kr, and 147Pm. The dosimeters were supplied by two different services, and all irradiations were performed at the PTB Institute in Germany. Each dosimetry service evaluated the dosimeters without knowledge that they had been purposefully irradiated. The accuracy and precision of the dosimeters were evaluated as a function of delivered dose, energy of beta particles and angular incidence. The results are compared to performance measures recommended by the IEC. Both dosimeter types displayed significant energy dependence. Angular dependence was moderate. Accuracy and precision as a function of dose (linearity) differed between the two systems, with the MCP-Ns being noticeably better than the GR200A. The superior precision makes the MCP-Ns much more useful for extremity dose measurements. The differences between these two dosimeter systems reinforce the need to evaluate a dosimeter carefully before using it in the daily work routine.

[Quality evaluation of a personal dosimetry service]

In a hospital environment high quality personal dosimetry is demanded by two different considerations: first, the marked reduction in the radiation exposure levels of hospital workers during the last 10 years and second, the recent decrease in the allowed absorbed dose thresholds for the different categories of workers and for the general population. In fact, according to the new Italian Radioprotection Law (D.L. vo 230/95), the dose equivalent limit for the general population has been decreased to 1 mSv per year. This means that a dosimetric system should be able to measure, with acceptable precision and accuracy, dose levels as low as 0.1 mSv per observation period (generally 1 month or 45 days). This is quite a stringent requirement for this kind of dosimetry. During a tender, the performances of the whole body personal dosimetry systems by four Italian service providers were analyzed by irradiating more than 60 test samples for each provider with four different energies in a wide dose interval (0.01-100 mSv). The results show that all systems perform quite well in the 0.2-100 mSv dose range; on the contrary, in the 0.01-0.2 mSv dose range, significant differences appear between the services and TLD based systems perform better than film based ones. In particular, one of the two TLD based systems measured doses as low as 0.01 mSv. To conclude this very high sensitivity level really opens a new "observation window" on the low doses world. The use of higher quality (and, of course, more expensive) materials by this provider seems to be the key of its success.

[Quality assurance in radiology: quality control of radiographic cassettes]

A "quality team" in radiology, whose members are the authors of this paper, has implemented a quality control program to test the cassettes with intensifying screen systems used in radiology departments. 149 systems-124 of them for general purpose radiology and 25 for mammography-were submitted to the following tests: visual inspection of radiographic cassettes and intensifying screens, screen-film contact, intensifying screen cleanliness and relative sensitivity of the intensifying screens. The results of each type of test are reported in detail in the paper, on a 3-point scale: good, sufficient and poor. The overall results of the quality control tests show 78% of general purpose radiology cassettes to qualify as good (69%) or sufficient (9%), while 22% were of poor quality. 88% of the mammographic cassettes qualified as good (76%) or sufficient (12%), while 12% were of poor quality. All tests were easy to perform and required limited resources. The necessary procedures to keep quality high over time are also reported. To conclude, the results obtained with our quality control program could be used as an effective tool to address and plan the turnover of the cassettes with intensifying screens which are usually used in diagnostic radiology practice.

[Evaluation of the quality of screen-film radiographic systems: physical principles and methods of measurement]

Comparative evaluation of radiographic film-screen systems presents several problems from both the theoretical and the experimental point of view. From the theoretical point of view the main difficulties are related to the choice of the parameters best suited to express the "overall quality" of a system. From the practical point of view the main problem is that to measure some basic quantities (resolution and noise) sophisticated and expensive instruments are required. This paper deals with both these problems. To express image quality we have assumed the signal-to-noise power ratio: this index depends in a explicit way on contrast, resolution and noise of the system. The dependence on sensitivity is implicit and was derived using literature data. From a knowledge of the dependence of image quality on sensitivity it is possible to develop an "overall quality" index which is considered to express the "technological level" of the system. This index can be used in the comparative evaluation of the different systems. In this work some basic physical quantities (characteristic curve, sensitivity) were evaluated using standard instruments. To measure spatial resolution and noise an inexpensive, PC-based, TV-digitizer system was developed. As an example, both image and overall quality indices were evaluated on three mammographic systems which are typical of the three different "phases" of the development of this technique.