Biomedical subjects

A C Traino

Publications and source records attributed to A C Traino.

11 recordsLinked to original sources

PubMed2006

A dosimetric algorithm for patient-specific 131I therapy of thyroid cancer based on a prescribed target-mass reduction.

(131)I therapy is used in the treatment of differentiated thyroid cancer both to ablate the post-surgical thyroid remnant and to treat recurrent or metastatic cancer. The optimum administered activity for ablation remains controversial: the most commonly used method is the administration of a fixed radioiodine activity (1110-3700 MBq or more); an alternative is the administration of an activity individually calculated to deliver a prescribed absorbed dose (usually 300 Gy for remnant ablation and 80 Gy for treatment of metastasis). Neither of these two approaches is based on a theoretical model and for this reason the debate on the optimization of (131)I therapy of thyroid cancer could have a weak grounding. In this paper, the meaning of the fixed value of target absorbed dose (Gy) is discussed and a mathematical model for remnant/metastasis optimum absorbed dose calculation is presented. This model is based on the desired reduction of the volume of the target (remnant or metastasis) and allows one to calculate individually the value of the optimum target absorbed dose (Gy) and consequently the optimum therapeutic activity to administer to the patient.

Algorithms↗

PubMed2005

Ion recombination correction for very high dose-per-pulse high-energy electron beams.

The parallel-plate ionization chamber is the recommended tool for the absorbed dose measurement in pulsed high-energy electron beams. Typically, the electron beams used in radiotherapy have a dose-per-pulse value less then 0.1 cGy/pulse. In this range the factor to correct the response of an ionization chamber for the lack of complete charge collection due to ion recombination (ksat) can be properly evaluated with the standard "two voltage" method proposed by the international dosimetric reports. Very high dose-per-pulse electron beams are employed in some special Linac dedicated to the Intra-Operatory-Radiation-Therapy (IORT). The high dose-per-pulse values (3-13 cGy/pulse) characterizing the IORT electron beams allow to deliver the therapeutic dose (10-20 Gy) in less than a minute. This considerably reduces the IORT procedure time, but some dosimetric problems arise because the standard method to evaluate ksat overestimates its value by 20%. Moreover, if the dose-per-pulse value >1 cGy/pulse, the dependence of ksat on the dose-per-pulse value cannot be neglected for relative dosimetry. In this work the dependence of ksat on the dose-per-pulse value is derived, based on the general equation that describes the ion recombination in the Boag theory. A new equation for ksat, depending on known or measurable quantities, is presented. The new ksat equation is experimentally tested by comparing the absorbed doses to water measured with parallel-plate ionization chambers (Roos and Markus) to that measured using dose-per-pulse independent dosimeters, such as radiochromic films and chemical Fricke dosimeters. These measurements are performed in the high dose-per-pulse (3-13 cGy/pulse) electron beams of the IORT dedicated Linac Hitesys Novac7 (Aprilia-Latina, Italy). The dose measurements made using the parallel-plate chambers and those made using the dose-per-pulse independent dosimeters are in good agreement (<3%). This demonstrates the possibility of using the parallel-plate ionization chambers also for the very high dose-per-pulse (> 1 cGy/pulse) electron-beam dosimetry.

Algorithms↗

PubMed2004

A minimally invasive method to evaluate 131I kinetics in blood.

The dose limiting factor for 131I therapy in patients with thyroid cancer is myelotoxicity, thus an accurate determination of radioiodine activity in the red marrow is of paramount importance. The reference method for red marrow dosimetry in radiometabolic therapy is based on the measurement of radioiodine kinetics, particularly the activity/time curve in blood. Such a measurement requires withdrawal of blood samples at various times after 131I administration. This procedure involves some potential risk from the radiation protection point of view, such as possible contamination of personnel with blood and disposal of the radioactive blood samples (and syringes). We present here a minimally invasive method to evaluate radioiodine kinetics in the blood, which only requires one blood sample and a set of measurements on the patient's thigh made with a collimated NaI(Tl) probe. The method has been validated in four patients treated with 131I for thyroid cancer.

Adult↗

PubMed2002

A theoretical model for prescription of the patient-specific therapeutic activity for radioiodine therapy of Graves' disease.

A fundamental function of the thyroid is to extract iodine from the blood, synthesize it into thyroid hormones, and release it into the circulation under feedback control by pituitary-secreted hormones. This capability of the thyroid, termed as functionality, can in principle be related to the severity of hyperthyroidism in individual patients. In this paper the uptake and release of 131I by the thyroid following the administration of 131I therapy for Graves' disease has been theoretically studied. The kinetics of iodine in the thyroid and blood have been evaluated using a two-compartment model. This simplified model appears to be adequate for dosimetry purposes and allows one to correlate levels of increased thyroid functionality (hyperthyroidism) with clinically measurable kinetic parameters. An expression has been derived for the rate of change of thyroid mass following therapy; this has the same form as an empirical relationship described in an earlier work. A method is presented for calculation of the amount of radioiodine activity to be administered to individual patients in order to achieve the desired final functionality of the gland. The activity to be administered is based on measurements of 131I kinetics after the administration of a 'low-activity' (1850 kBq) tracer for treatment planning.

Graves Disease↗

PubMed2001

Tc 99m-Sestamibi scintimammography in the differentiation of benign and malignant breast microcalcifications.

The capability of the mammography-scintimammography combination to distinguish between benign and malignant isolated clusters of breast microcalcifications is discussed. Scintimammography using Tc 99m-Sestamibi was performed in 97 women with an isolated cluster of microcalcifications on mammograms. Seventy-two women had final histopathologic diagnoses (24 cancer and 48 benign pathology). The other 25 patients had follow-up to 3 years. The results of mammography, scintimammography and mammography-scintimammography combination were divided into five groups, based on the suspicion of malignancy. The sensitivity, specificity, false negative fraction, false positive fraction, predictive positive value, predictive negative value and diagnostic accuracy were calculated varying the diagnostic threshold. The Receiver Operating Characteristic (ROC) statistical technique was employed to compare the diagnostic value of mammography to mammography-scintimammography combination. The area under the ROC curves was calculated by the Wilcoxon statistic without any hypothesis on data distribution. The detected difference between areas under the mammography ROC curve (area=0.854, standard error=0.049) and mammography-scintimammography ROC curve (area=0.897, standard error 0.033) was statistically significant (P>0.05, one tail). The area under a ROC curve represents the probability that a randomly chosen diseased or non-diseased subject could be correctly classified. From this point of view this paper demonstrates that, if properly used, scintimammography can add to mammography in the characterization of an isolated cluster of microcalcifications, even if it is not able to replace FNAB and core biopsy.

Journal Article↗

PubMed2001

Study of the correlation between administered activity and radiation committed dose to the thyroid in 131I therapy of Graves' disease.

Substantial reduction in the thyroid volume (up to 70-80%) after 131I therapy of Graves' disease has been demonstrated and reported in the literature. Recently a mathematical model of thyroid mass reduction during the first month after therapy has been developed and a new algorithm for the radiation committed dose calculation has been proposed. Reduction of the thyroid mass and the radiation committed dose to the gland depend on a parameter k, defined for each subject. The calculation of k allows the prediction of the activity to administer, depending on the radiation committed dose chosen by the physician. In this paper a method for calculating k is proposed. The calculated values of k are compared to values derived from measurements of the changes in thyroid mass in twenty-six patients treated by 131I for Graves' disease. The radiation committed dose to the thyroid can be predicted within 21%, and the radioiodine activity to administer to the patient can be predicted within 22% using the calculated values of k. The thyroid volume reduction during the first month after therapy administration can be also predicted with good accuracy using the calculated values of k. The radiation committed dose and the radioiodine activity to administer were calculated using a new, very simple algorithm. A comparison between the values calculated by this new algorithm and the old, classical Marinelli-Quimby algorithm shows that the new method is more accurate.

Algorithms↗

PubMed2000

Influence of thyroid volume reduction on calculated dose in radioiodine therapy of Graves' hyperthyroidism.

Administration of radioactive iodine (131I) is an effective treatment for hyperthyroidism due to Graves' disease. Recently several investigators have shown that the success of this therapy may depend on the absorbed dose to the thyroid. Thyroid dose varies inversely with the mass of the gland. Much experimental evidence demonstrates that a reduction of the thyroid volume (mass) may occur after radioiodine therapy. In this work we evaluate the influence of the volume reduction on the calculation of the absorbed dose to the thyroid. A mathematical model of thyroid mass reduction after 131I therapy is presented, based on masses evaluated with ultrasonography of ten patients treated in the endocrinology department of our hospital. This model was applied to the general formula for calculation of the thyroid doses in these patients. The dose values obtained considering a reduction of thyroid mass after the treatment are often quite different from those obtained without considering change in mass (from 9% to 30% greater). We conclude that the consideration of thyroid mass reduction is important for an accurate estimation of the calculated dose.

Graves Disease↗

PubMed1999

[Study and implementation of a computerized program for personalized prescriptions for patients treated with radioiodine to be discharged].

INTRODUCTION: Iodine-131 (131I) therapy is widely used to treat some thyroid diseases such as hyperthyroidism and thyroid carcinoma. The discharge of a radioiodine treated patient is a potential problem for the radiation protection of the general population. To keep the absorbed dose to the general population as low as possible, patients are given some recommendations, on discharge usually a quite standard list of behaviors to avoid for an amount of time depending only on the administered activity. Thus, recommendations usually consider neither the individual kinetics of 131I nor disease type, while both factors account for major differences in iodine uptake and retention. We investigated the feasibility of customizing recommendations according to recent Euratom guidelines. MATERIAL AND METHODS: Individual 131I kinetics can be evaluated from previous work characterizing dose rate decay as a function of time for different thyroid diseases, together with measurements of iodine uptake or dose rate to the patient. Based on individual kinetics, the committed effective dose to the general population is calculated according to the kind of relationship with the patient, resulting in different amounts of time spent near him/her. RESULTS: The calculation procedure was implemented in a user-friendly software which requires input of few data and measurements to give each patient a customized list of precautions. Using the program on patient's discharge takes no longer than 10 minutes. The precautions are in good agreement with those reported in the literature. CONCLUSIONS: We have been using our program for nine months. Data show that most patients treated for thyroid cancer must follow the recommendations for a shorter time than hyperthyroid patients. The program is suitable for routine use in a nuclear medicine department.

Feasibility Studies↗

PubMed1999

[Correlation of ultrasound and galactography in the diagnosis of nipple discharge. Preliminary results].

INTRODUCTION: Several pathologic conditions involving the breast ductal tree can cause bloody or serous nipple discharge. Galactography plays a major clinical role in identifying and localizing intraductal masses, but its sensitivity in detecting cancer is certainly suboptimal. Presently high-frequency ultrasound (US) probes allow detection and guided biopsy of intraductal lesions. We compared the specific information provided by US and galactography in the discharging breast. MATERIAL AND METHODS: Thirty-three patients with discharging breast were submitted to both diagnostic examinations. US was performed with 13 MHz scanheads both before and after galactography. Galactography was performed with 30-31 G catheters to cannulate the discharging duct. Nonionic, water-soluble, sterile contrast material was administered. Postgalactography US was performed to investigate if it could yield further information. The final diagnosis was made at histology and 2 years' instrumental follow-up. RESULTS: Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) were evaluated for both techniques. We considered a positive finding the detection of a lesion in general (be it papilloma, papillomatosis, or cancer), as well as the detection of carcinoma only. Sensitivity was 96% for galactography and 84% for US in the former case, versus 50% and 100%, respectively, in the latter. Postgalactography US added no major information. DISCUSSION AND CONCLUSION: US is more sensitive than galactography in cancer diagnosis and, it permits guided biopsy and preoperative localization of unpalpable ductal lesions. In our limited experience, US can be considered a complementary diagnostic tool to galactography in the discharging breast.

Adult↗

PubMed1994

[Computer-assisted combined management of physical radiation protection and quality control of X-ray diagnostic equipment].

A software for the computer-assisted management of radiation protection and quality control of radiodiagnostic equipment is described. The code was written in DB3-plus language. In addition to some independent archives on X-ray diagnostic systems identification, it includes technical and radiation protection checks, environmental dosimetry in the controlled areas and on workers. The data can be searched through a key field and periodical radiation protection reports and action reports can be printed. The software programs can also perform some "intelligent" operations such as the calculation of controlled areas range and the classification of X-ray diagnostic systems and workers. This is done by retrieving the information from the archives. The software can be updated, revised and modified very easily, due to the non-connection of the archives. It is also very simple to connect DB3-plus archives with many other software packages to process and elaborate data. This software is the core of an integrated system we are developing to store and process data from diagnostic X-ray systems control meters and from our TLD personal dosimetry equipment.

Computer Systems↗

PubMed1991

Resampling algorithms for diagnostic radiology.

The use of digital image resampling can be highly suitable for diagnostic radiology. It can be applied not only to obtain zoom effects but also to solve various problems related to the comparison of images of different origin (NMR, CT, NM). The mathematical approach to this kind of algorithm, based on rational assumptions, can be very wide and diversified. In this work the principles of the stochastic and of the analytical methods have been analyzed. In particular, a complete mathematical treatment of the integral analytical methods, which are both the most theoretically interesting and analytically complex, has been performed. The practice of these techniques has to be determined each time from the analysis of the specific problem to which they are to be applied in the routine, and after a retrospective analysis of the results obtained.

Algorithms↗