National survey to update the diagnostic reference levels in interventional radiology procedures in Italy: working methodology.

Interventional Radiology (IR) deals with the diagnosis and treatment of various diseases through medically guided imaging. It provides unquestionable benefits to patients, but requires, in many cases, the use of high doses of ionizing radiation with a high impact on radiation risks to patients and to overall dose to the population. The International Commission on Radiological Protection introduced Diagnostic reference levels (DRLs) as an effective tool to facilitate dose verification and optimize protection for patients undergoing radiological procedures. In addition, EURATOM Council Directive 2013/59 and its Italian transposition (Legislative Decree 101/2020) have reiterated that DRLs must be established for many common radiological diagnostic procedures to compare the radiation dose delivered for the same diagnostic examination. Within this framework, Istituto Superiore di Sanità-Italian National Institute of Health (ISS)-, in collaboration with relevant Italian Scientific Societies, has provided documents on DRLs in radiological practices such as diagnostic and IR and diagnostic nuclear medicine. These reference documents enable National Hospitals to comply national regulation. The implementation of DRLs in IR is a difficult task because of the wide distribution of doses to patients even within the same procedure. Some studies have revealed that the amount of radiation in IR procedures is influenced more by the complexity of the procedure than by the weight of the patient, so complexity should be included in the definition of DRLs. For this reason, ISS promoted a survey among a sample of Italian Centers update national DRL in IR procedures with related complexity factors than can be useful for other radiological centers and to standardize the DRLs values. In the present paper the procedural methodology developed by ISS and used for the survey will be illustrated.

Conversion factors of effective and equivalent organ doses with the air kerma area product in patients undergoing coronary angiography and percutaneous coronary interventions.

To derive effective dose (E), organ dose (HT) and conversion factors with the air kerma area product (KAP) in coronary angiography (CA) and percutaneous coronary intervention (PCI) by the radial route, using the ICRP 103 tissue weighting factors. The study included 34 patients referred for CA and 31 for PCI. E and HT were derived from in-the-field KAP measurements using Montecarlo methods. Median KAP of 23.2 and 56.8Gycm2 and E of 6.9 and 20.0mSv were found for CA and PCI, respectively. Mean KAP and E were significantly higher in males than in females (52.4±40.0 vs 32.3±16.6Gycm2; p=0.02) and (16.8±13.6 vs 10.7±5.8mSv; p=0.04). KAP (r=0.39; p=0.001) and E (r=0.34; p=0.005) showed a significant correlation with the patient's weight. Conversion factors between KAP and E (E/KAP) were 0.30±0.04mSvGy-1cm-2 for CA and 0.33±0.05mSvGy-1cm-2 for PCI. No significant differences in the E/KAP between males and females were found (0.31±0.05 vs 0.33±0.05; p=0.08). Again, no significant correlation was found between E/KAP and patient's weight (r=0.23; p=0.07). The correlation between E and KAP was excellent for CA (r=0.99) and PCI (r=0.96). The correlation between HT and KAP ranged from r=0.87 to r=1 and from r=0.71 to r=0.98 for CA and PCI, respectively. A single factor, the total KAP, could be used for a specific acquisition protocol to reliably estimate E and HT without the need of a patient's specific analysis. Conversion factors might be installation, X-ray beam quality or protocol dependent.

Optimisation of radiological protocols for chest imaging using computed radiography and flat-panel X-ray detectors.

PURPOSE: Digital radiography technology has replaced conventional screen-film systems in many hospitals. Despite the different characteristics of new detector materials, frequently, the same radiological protocols previously optimised for screen film are still used with digital equipment without any critical review. This study addressed optimisation of exposure settings for chest examinations with digital systems, considering both image quality and patient dose. MATERIALS AND METHODS: Images acquired with direct digital radiography equipment and a computed radiography system were analysed with specially developed commercial software with a four-alternative forced-choice method: the most promising protocols were then scored by two senior radiologists. RESULTS: Digital technology offers a wide dynamic range and the ability to postprocess images, allowing use of lower tube potentials in chest examinations. The computed radiography system showed both better image quality and lower dose at lower energies (85 kVp and 95 kVp) than those currently used (125 kVp). Direct digital radiography equipment confirmed both its superior image quality and lower dose requirements compared with the storage phosphor plate system. CONCLUSIONS: Generally, lowering tube potentials in chest examinations seems to allow better image quality/effective dose ratio when using digital equipment.

Radiation doses to the population of the Emilia-Romagna region from medical exposures.

PURPOSE: The aim of this study was to supplement the analysis of data related to conventional radiography (CR), computed tomography (CT) and nuclear medicine (NM) with those related to interventional radiology (IR), and illustrate the contribution of all these radiological procedures to radiation exposure of the Emilia-Romagna population in Italy. MATERIALS AND METHODS: We gathered information about the number and mean doses of 30 interventional procedures performed in 17 hospitals of the Emilia-Romagna region. Seven hospitals were selected, and requests were made for numerical values of the dose-area product (DAP) in various IR procedures measured in the field. From these values, we calculated the 2006 annual collective effective dose (S), per-procedure dose and total dose, as well as the average per-capita dose to the Emilia-Romagna population. RESULTS: The 20 procedures amongst CR, CT, NM and IR that in 2006 contributed the most to Emilia-Romagna population radiation dose are described in detail: CR, CT, NM and IR contribute to approximately 10%, 66%, 9% and 15% of the total dose, and to 70%, 21%, 3% and 6% of procedure frequency, respectively. The S and average per-capita doses were 5,237 person-Sv and 1.2 mSv, respectively. CONCLUSIONS: IR procedures deliver high doses to the patient. Therefore, the same attention should be paid to radiation protection as with other high-dose examinations. As IR operators are often not radiologists, special attention should be paid to education in radiation protection of the professionals involved.

Temporal trend of diagnostic medical exposure to the Emilia-Romagna region population.

PURPOSE: This paper illustrates the annual trends in medical radiation exposure due to conventional radiography (CR), computed tomography (CT) and nuclear medicine (NM) procedures of the Emilia-Romagna population from 2001 to 2006. MATERIALS AND METHODS: We gathered information about the type, number and mean doses of CR, CT, and NM examinations performed in 17 hospitals of the Emilia-Romagna region. In particular, numerical values of the following dosimetric parameters were requested: entrance skin dose for CR, CT dose index and dose-length product for CT and activity administered for NM. Lastly, the annual collective dose S and annual average per-caput dose were calculated. RESULTS: The 13 diagnostic imaging procedures that were the greatest contributors to the Emilia-Romagna population dose between 2001 and 2006 were identified and, for the year 2006, their percentage contribution to total procedures and population dose are indicated. CR, CT and NM accounted for 12%, 78% and 10% of the dose, and 83%, 15% and 2% of total procedures, respectively. The annual trends of S and average per capita dose are shown, and the theory underlying the use of these parameters is briefly discussed. CONCLUSIONS: This type of study relies heavily on the analysis of field data and as such, the growing attention paid in recent years to procedure optimisation should continue, and expand even for the justification of the procedures themselves as justification has a significant impact on the reduction of S and per-caput doses.

Transjugular intrahepatic portosystemic shunt: a case report of rescue management of unrestrainable variceal bleeding in a pregnant woman.

Liver cirrhosis complications in pregnant women are frequent and death rate secondary to variceal bleeding is relevant. Both sclerotherapy and banding ligation seem to be safe procedures in pregnancy; when bleeding is not arrested endoscopically an emergency transjugular intrahepatic portosystemic shunt should be considered, but data regarding pregnant cirrhotic women are scarce. We describe the case of a pregnant woman at 14 weeks of gestation who underwent management of acute variceal bleeding by transjugular intrahepatic portosystemic shunt. Transjugular intrahepatic portosystemic shunt may represent a rescue treatment for failed attempts of band ligation or sclerotherapy.

Comparison of radiation doses to patients undergoing standard radiographic examinations with conventional screen-film radiography, computed radiography and direct digital radiography.

New flat-panel direct digital radiography equipment has recently been installed in our Accident and Emergency Department; its characteristics and versatility are well suited to the work undertaken in this environment. The aim of this study was to compare radiation doses to patients undergoing standard radiographic examinations using conventional screen-film radiography, computed radiography and direct digital radiography; entrance surface dose and effective dose were calculated for six standard examinations (a total of 10 projections) using standard patient exposure parameters for the three imaging modalities. It was found that doses for computed radiography (all examinations) were higher than the doses for the other two modalities; effective doses for direct digital radiography were approximately 29% and approximately 43% lower than those for screen-film radiography and computed radiography, respectively. The image quality met the criteria in the European guidelines for all modalities.

Monitoring of the medical radiological exposures of the population of the Emilia-Romagna Region.

PURPOSE: The Italian Decree of Law 187/2000 provides for many fulfilments relevant to justification and optimisation of medical exposures that can complicate the daily work of radiology departments if considered as mere legal requirements. On the contrary, this law should be regarded as a good opportunity to analyse and optimise working practices. To this end, the Emilia- Romagna Region carried out an initial assessment of medical exposures to its population in 2001 followed by a second survey taking into account new dosimetric evaluations. This paper illustrates the results of this second survey and analyses the most significant parameters in comparison with similar studies reported in the literature. MATERIALS AND METHODS: We first determined the examinations to be considered: 12 easily identifiable examinations divided into macroaggregates were selected for conventional radiography and computed tomography (CT). Hospitals of the Emilia-Romagna Region were directly asked to provide the number of examinations performed subdivided by type and grouped by nomenclature code, some technical parameters related to both examination protocol and equipment and the value of dose quantities as measured by local medical physicists. RESULTS: Study of distribution of the entrance skin dose for different examinations in single hospitals showed no systematic differences in kilovoltage settings versus dose whereas the number of examinations tended to be inversely proportional to dose. These trends could be explained by the fact that in hospitals where many examinations of the same type are performed, operators, equipment and procedures are well integrated, leading to a level of specialisation that allows efficient interaction in order to deliver an "optimal dose". Analysis of the "entrance skin dosemax"/"entrance skin dosemin" ratios for various projections and comparison with literature data seem to show that a "scale factor" has a fundamental role in the variability of entrance skin dose values amongst hospitals and that "chest" examinations are the most critical, with the greatest differences in entrance skin doses. CONCLUSIONS: The evaluations performed in this study show that this type of analysis heavily relies not only on the cooperation of all professionals responsible for patient radiation protection but also on the experience gained during previous surveys because data collection is a very critical process that can invalidate, if not carefully performed, all subsequent processing.

Quality control of 99Mo/99Tcm generators: results of a survey of the Radiopharmacy Working Group of the Italian Association of Nuclear Medicine (AIMN).

A multicentre survey of the quality control of 99Tcm generators has been completed: 245 generators from seven different commercial sources were tested over a period of 2 years. The results indicate that the mean pH of the eluates was 5.8 +/- 0.6; the aluminium contents were typically < 10 ppm; the radiochemical purity was 99.8 +/- 0.4% and the median 99Mo content was 3.8 x 10(-4) percent. The elution profiles gave a volume of 1.9 ml to obtain 50% of the total eluted activity and of 4.9 ml to obtain 95%. Other radionuclide impurities and heavy metal breakthrough were evaluated by graphite furnace absorption spectrometry and inductively coupled plasma mass spectrometry. National guidelines for the standardization of radiopharmacy procedures are currently being compiled.

[Performance assessment of mammographic diagnostic systems: evolution of methods and their application to a digital image study]. / Valutazione delle prestazioni dei sistemi diagnostici mammografici: evoluzione delle metodiche e loro applicazione a uno studio di immagini digitalizzate.

INTRODUCTION: "Receiver Operating Characteristic" (ROC) curves are one of the most efficient analysis tools for the complete evaluation of a diagnostic system performance. However this method is limited in visualizing and locating abnormal structures, such as clusters of microcalcifications on mammographic images. Other more refined and complex techniques have also been suggested, where particular statistical hypotheses are assumed, namely the "Free-response ROC" (FROC), the "Alternative FROC" (AFROC) and the "Free-response Forced Error" (FFE) analyses. We studied the theoretical bases of these different methods and their experimental applications to assess the correctness of the hypothetical statistical distributions. MATERIAL AND METHODS: We considered two statistical hypotheses: first, that the false-positive response distribution follows the Poissonian statistics; second, that "signal" and "noise" distributions have a Gaussian trend with different means and variances. Thus, we applied the different methods to the responses given by 8 observers (5 radiologists and 3 medical physicists) who independently evaluated 3 digital mammographic samples. Every sample consisted of 39 images, with 1-15 clusters each (total: 100 clusters). The samples were obtained from 39 images available in an Internet database (sample 1); 2 different digital filters were applied to each image (samples 2 and 3). To collects responses, we provided for two phases: first, every observer visualized and located the clusters at a given confidence level; second, when a false-positive response was given, spontaneously or after forcing, the responses were ordered by decreasing conspicuity. Finally, data were analyzed with a "home-made" software by applying the FROC and AFROC analyses to the data collected in phase 1 and the FFE analysis to those collected in phase 2. RESULTS: We considered the area under the AFROC curve as the most important parameter: the values obtained with the 3 types of analysis are well in agreement within their uncertainties. In particular, the FROC-AFROC agreement did not exceed 5.9% (10 of 14 cases within 2.5%), while the FFE analysis had higher standard deviations associated with the area value (about 10%). The interpolated curves from both FROC and AFROC data were very similar. The three methods had various advantages: the FFE is very simple to calculate and makes the most of the information given by the observer; FROC and AFROC can provide true-positive and false-positive responses on the same image, which permits to optimize the evaluation of a diagnostic system performance. The statistical tools used in the simplest methods are usually integrated with the completeness characteristics of the location of multiple signals on mammograms. CONCLUSIONS: In theory, every method is necessary because it provides additional information to validate the statistical hypotheses under investigation. In fact, when the methods are used to evaluate and compare several diagnostic systems, the results of the three techniques are equivalent. Therefore, choosing a specific technique depends on both available resources and response type all the hypothetical statistical distributions in our study proved correct.

Evaluation of lung clearance of inhaled pertechnegas.

Pertechnegas is a new ventilation agent produced by modifying the atmosphere of combustion of Technegas. Due to its rapid disappearance from the lungs, Pertechnegas has been suggested as useful in measuring pulmonary epithelial permeability. This study aimed to assess the reliability of ventilation scans with Pertechnegas to evaluate alveolar-capillary permeability. Six non-smokers with no evidence of pulmonary disease were investigated. Scintigraphic data were used to evaluate the site of Pertechnegas deposition (by assessing the Penetration Index [PI] of the gas), its clearance rate (by calculating the time to half-clearance [T1/2]) and its lung distribution (by means of a pixel-by-pixel analysis. PI measurements produced a mean value of 88.8 +/- 13.3% (range 69-117%). Time activity curves showed a fast clearance in all cases (mean T1/2 = 10.7 +/- 2.1 min, range 8.1-14.3 min). Comparison of statistical indices of uniform deposition (skewness and kurtosis) indicated satisfactory homogeneity of Pertechnegas distribution throughout the lungs. These data show that after inhalation Pertechnegas has a peripheral deposition and a homogeneous distribution in the lungs and is rapidly cleared through the alveolar-capillary barrier. In conclusion Pertechnegas can be recommended as a potential radiopharmaceutical for studying the pulmonary epithelial barrier.

Early pulmonary involvement in systemic sclerosis assessed by technetium-99m-DTPA clearance rate.

UNLABELLED: Systemic sclerosis (SS) is frequently associated with interstitial lung disease, but clinical symptoms and radiologic abnormalities may occur late in the course of the disease. This study investigated early pulmonary involvement by assessing the clearance rate of inhaled 99mTc-diethylenetriaminepentaacetic acid (DTPA). METHODS: Sixteen patients with proved SS, no clinical pulmonary symptoms and normal chest radiogram were prospectively studied. The 99mTc-DTPA clearance rate was calculated as the time to half clearance (T1/2) and compared with values obtained in healthy nonsmokers. RESULTS: Six patients showed abnormally increased clearance (T1/2 < 53 min). Rapid clearance was not correlated to SS disease duration or to abnormal pulmonary function tests. Five of six patients with abnormally increased clearance underwent high-resolution CT, which in all five demonstrated pathologic findings that were suggestive of early interstitial disease. CONCLUSION: These findings indicate that in SS asymptomatic patients may frequently present with abnormal 99mTc-DTPA clearance; 99mTc-DTPA lung scintigraphy may allow early detection of subclinical pulmonary involvement in SS.

[En-bloc treatment of tumors of the hypopharyngeal-laryngeal-tracheal tract with a new isocentric multipendular technic]. / Trattamento in blocco dei tumori del tratto ipofaringo-laringo-tracheale con una nuova tecnica multipendolare isocentrica.

The authors propose a new technique for the treatment of hypopharyngeal-laryngeal-tracheal tract tumors using cobalt-60 irradiation. This technique allows the simultaneous irradiation of both primary tumor and cervical lymph nodes. Therapeutically effective doses can be administered without affecting the spinal cord. The above-mentioned technique consists of 3 isocentric rotations, the widest one carried out by interposing a small lead bar shielding in the middle of the field. Dose distributions obtained in an Alderson-Rando phantom and in a patient are reported.