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Purpose: The aim of this study was to describe magnetic resonance imaging (MRI) patterns in 21 patients with histologically proven invasive lobular cancer (ILC) of the breast., Materials and Methods: We retrospectively reviewed MR images of 21 out of 24 women with ILC of the breast. Three women were excluded from the study because they underwent neoadjuvant chemotherapy after MRI. Thirteen of the 24 women had positive clinical findings. All 24 patients underwent mammography, sonography and MRI. MRI was performed to evaluate disease extent and multifocality/multicentricity before modified radical mastectomy (n=5) or quadrantectomy (n=16). Two experienced radiologists reviewed the MRI scans and described the tumour patterns., Results: We identified five morphological patterns of ILC: a solitary mass with irregular margins (n=8); a mass with smooth margins (n=5); multiple small enhancing foci with interconnecting enhancing strands (n=4); dominant lesion surrounded by small foci (n=3); one MR examination was negative., Conclusions: Architectural and dynamic features are important in the interpretation of breast MRI findings. ILC may be detected on MRI as solitary or multiple lesions that correspond to tumour morphology on pathologic examination. False-negative MRI findings do occur in a small percentage of ILC.

The noise power spectrum, or Wiener spectrum, of the radiographic mottle is a fundamental quantity in film-screen image quality evaluation. In this paper, using a high-quality computerized microdensitometer, two different acquisition and calculation methods for noise evaluation are compared. The first one is the classic (unidimensional) method used in film noise evaluation: a long and narrow slit (10 x 400 microns2) is used to delimit the microdensitometer light beam and the transmission data are collected by scanning the sample in a rectilinear pattern. A section of the two-dimensional Wiener spectrum is thus obtained. The second (two-dimensional) method is similar to that used in digital image noise evaluation: a square slit is used on the microdensitometer window and data are collected by scanning the sample on a square pattern. To evaluate the effect of different sampling frequencies, our data were acquired both selecting a 50 x 50 microns2 square slit and a 20 x 20 microns2 square slit. The two-dimensional Wiener spectrum thus obtained is then reduced to a unidimensional function. The measurements were made on two different films (Kodak Ortho G e Kodak T-MAT G) exposed with the same screen (Kodak Lanex Regular). These films have the same sensitivity but a different emulsion structure. One film (Ortho G) is made of irregular halide silver grains and the other (T-MAT G) of tabular grains. A satisfactory agreement between the two procedures was found which makes the comparison of data from the laboratories using microdensitometers and those using TV-grabbing system for film-screen evaluation meaningful.

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.

In breast cancer adjuvant therapy, respiratory movements continuously modify the irradiated volumes and the anatomical shape of this body region. Fifteen patients were submitted to 3 Computed Tomography (CT) sequences for treatment planning: the first one without any indications to the patient (the standard sequence) and the second and the third one with spontaneous stopped inspiration and expiration, respectively; the patient was always in the same position. The treatment was planned on standard CT images and then applied to the other sequences, maintaining all parameters unvaried, including isocenter position and treatment time. The lung volumes within the fields (and those included in the 95%, 100%, 105% isodoses referred to the prescribed dose) were evaluated with dose/volume histograms. The average irradiated lung was 69 cm3 (DS 28) in standard sequences, 136 cm3 (DS 67) in inspiration and 41 cm3 (DS 25) in expiration. The pulmonary volume within the above isodoses exhibited similar changes. In other words, the lung volume actually irradiated during the whole treatment is smaller than the one which can be calculated on standard CT sequences and it corresponds to expiration volume. The remaining part falls into a wide "twilight zone" relative to dose. Therefore, the true risk of lung toxicity can be similarly lower than the calculable one on standard CT images. Thus, the complication risk (based on dose/volume histograms and normal tissue control probability parameters) could be assessed in new prospective studies, introducing a corrective factor for the irradiated lung volume, because the latter is smaller than that shown by standard CT.

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.

The comparative evaluation of radiographic screen-film systems presents several problems from both the theoretical and the experimental points 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. This quantity is expressed as a product of image quality index and system sensitivity. As image quality index we assumed the signal-to-noise power ratio: this index depends in an explicit way on contrast, resolution and noise of the system. From the experimental point of view the main problem is that to measure some basic quantities, sophisticated and expensive equipment, like computer-controlled microdensitometers, is generally required. In this paper, we report the Italian Association of Biomedical Physicists Task group suggestions for measuring the basic physical parameters (with particular reference to the use of cost-effective equipment and for purchasing specification drafting). Using synthetic quality indices, the evaluation criteria of radiographic materials are directly derived from the general theory of radiographic image perception.

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.

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.

A recently developed computer program for three-dimensional (3D) reconstruction of SPECT images has been employed to study myocardial perfusion in coronaropathic patients using MIBI-99mTc or 201Tl chloride. By subtracting after-stress from at-rest 3D reconstructed images, even small ischemic lesions could be located in the myocardium, with good morphological definition. The general characteristics of the method and some clinical results are here presented.

Absorption in water of 42 MV X-rays is described by means of equations whose parameters have been determined in such a way as to best fit the experimental data. The results obtained are employed in a general program for the calculation of dose distribution in external radiotherapy.

Magnetic Resonance (MR) cross sectional images of the normal mediastinum are presented and discussed. In normal subjects most mediastinal structures visible on Computed Tomography (CT) are also visible using MR. The primary advantages of MR over CT in the evaluation of mediastinum are the greater soft tissues contrast resolution, the multiplanar (axial, coronal and sagittal) display of the mediastinal anatomy and its ability to distinguish vascular from nonvascular structures without injection of contrast media.

In order to understand how pulse sequences affect what is black and what is white in Nuclear Magnetic Resonance (NMR) images, the tissue parameters (proton density; relaxation times T1 and T2) are related to the operator selectable controls (type of pulse sequence; repetition time TR; interpulse delay TI; echo delay TE). The pulse sequences "Saturation Recovery"; "Inversion Recovery"; "Spin Echo" are discussed. The authors also analyze the effect of flowing blood on NMR images.

The authors discuss the problem of radiation damage to the individual developing in utero, and summarize the information available in the literature on the subject. Additional risks induced by ionizing radiations are classified with reference to gestational age and dose absorbed by the fetus. Such risks concern the possibility of mental retardation from the 8th to the 15th gestational week, and of developing a malignant disease from the 3rd to the 15th gestational week. We report the dose values received by the fetus as a result of both radiodiagnostic examinations and the Chernobyl nuclear accident: the doses were generally very low, which leads us to the conclusion that additional risks are of the same order of magnitude as the fluctuations in the natural congenital malformations. Thus, prenatal irradiation for diagnostic examinations does not generally represent a reason to recommend therapeutic abortion. However, it is always important to carry out a careful evaluation of the dose absorbed by the fetus and to correctly inform the mother about eventual radiation-induced risks.

The energy dissipation of high energy electron beams in water, assuming a "continuous slowing down", is expressed by means of the "transport" and "age diffusion" equations: this allows the automatic calculation of the dose distribution in space. The agreement between calculated and measured values is discussed.

Various physical parameters are described for evaluation of the quality of the irradiation plane. Of these, the integral dose and the dose gradient index are regarded as particularly significant and their calculation is included in a computerised dosimetry programme. Examples are drawn from the comparison of various mediastinum irradiation techniques: 60Co, high energy X-rays, fast electrons.

Spatial resolution, statistical noise and patient dose are important parameters for the evaluation of the performances of CT-scanners. These parameters may be combined to develope some "synthetic indices", able to describe intrinsic properties of a CT-scanner (the maximum obtainable spatial resolution and dose efficiency). This type of analysis has been applied to the evaluation of four CT-scanners, three of 3rd and one of 4th generation.

Twenty-nine prostatic cancer patients were evaluated for staging purpose by Magnetic Resonance (MR). MR findings were correlated with the pathologic examination in 18/29 patients who underwent radical prostatectomy. Four MR staging parameters were evaluated individually: periprostatic fat; periprostatic venous plexus; seminal vesicles and pelvic adenopathy. MR correctly staged 16/18 patients, with one case of overstaging and one case of understaging. The diagnostic accuracy of MR in differentiating intracapsular stage B from extracapsular stage C was 87%, with a sensitivity of 90% and a specificity of 87%. MR and CT results agreed in 4 of the 7 operated patients who were examined with both techniques; in 3 cases there was disagreement, and MR was correct.