Step-and-Shoot IMRT by Siemens Beams: An EPID Dosimetry Verification During Treatment.

PURPOSE: This work reports the extension of a semiempirical method based on the correlation ratios to convert electronic portal imaging devices transit signals into in vivo doses for the step-and-shoot intensity-modulated radiotherapy Siemens beams. The dose reconstructed at the isocenter point Diso, compared to the planned dose, Diso,TPS, and a γ-analysis between 2-dimensional electronic portal imaging device images obtained day to day, seems to supply a practical method to verify the beam delivery reproducibility. METHOD: The electronic portal imaging device images were obtained by the superposition of many segment fields, and the algorithm for the Diso reconstruction for intensity-modulated radiotherapy step and shoot was formulated using a set of simulated intensity-modulated radiotherapy beams. Moreover, the in vivo dose-dedicated software was integrated with the record and verify system of the centers. RESULTS: Three radiotherapy centers applied the in vivo dose procedure at 30 clinical intensity-modulated radiotherapy treatments, each one obtained with 5 or 7 beams, and planned for patients undergoing radiotherapy for prostatic tumors. Each treatment beam was checked 5 times, obtaining 900 tests of the ratios R = Diso/Diso,TPS. The average R value was equal to 1.002 ± 0.056 (2 standard deviation), while the mean R value for each patient was well within 5%, once the causes of errors were removed. The γ-analysis of the electronic portal imaging device images, with 3% 3 mm acceptance criteria, showed 90% of the tests with Pγ < 1 ≥ 95% and γmean ≤ 0.5. The off-tolerance tests were found due to incorrect setup or presence of morphological changes. This preliminary experience shows the great utility of obtaining the in vivo dose results in quasi real time and close to the linac, where the radiotherapy staff may immediately spot possible causes of errors. The in vivo dose procedure presented here is one of the objectives of a project, for the development of practical in vivo dose procedures, financially supported by the Istituto Nazionale di Fisica Nucleare.

Quasi-VMAT in high-grade glioma radiation therapy.

PURPOSE: To compare a quasi-volumetric modulated arc therapy (qVMAT) with three-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT) for the treatment of high-grade gliomas. The qVMAT technique is a fast method of radiation therapy in which multiple equispaced beams analogous to those in rotation therapy are radiated in succession. PATIENTS AND METHODS: This study included 12 patients with a planning target volume (PTV) that overlapped at least one organ at risk (OAR). 3D-CRT was planned using 2-3 non-coplanar beams, whereby the field-in-field technique (FIF) was used to divide each field into 1-3 subfields to shield the OAR. The qVMAT strategy was planned with 15 equispaced beams and IMRT was planned using 9 beams with a total of 80 segments. Inverse planning for qVMAT and IMRT was performed by direct machine parameter optimization (DMPO) to deliver a homogenous dose distribution of 60 Gy within the PTV and simultaneously limit the dose received by the OARs to the recommended values. Finally, the effect of introducing a maximum dose objective (max. dose < 54 Gy) for a virtual OAR in the form of a 0.5 cm ring around the PTV was investigated. RESULTS: The qVMAT method gave rise to significantly improved PTV95% and conformity index (CI) values in comparison to 3D-CRT (PTV95% = 90.7 % vs. 82.0 %; CI = 0.79 vs. 0.74, respectively). A further improvement was achieved by IMRT (PTV95% = 94.4 %, CI = 0.78). In qVMAT and IMRT, the addition of a 0.5 cm ring around the PTV produced a significant increase in CI (0.87 and 0.88, respectively), but dosage homogeneity within the PTV was considerably reduced (PTV95% = 88.5 % and 92.3 %, respectively). The time required for qVMAT dose delivery was similar to that required using 3D-CRT. CONCLUSION: These findings suggest that qVMAT should be preferred to 3D-CRT for the treatment of high-grade gliomas. The qVMAT method could be applied in hospitals, for example, which have limited departmental resources and are not equipped with systems capable of VMAT delivery.

Prospective multicenter study on the clinical utility of ca-72.4 in postmenopausal patients with pelvic mass.

The study objective was to evaluate the sensitivity and specificity as well as the positive predictive value and negative predictive value of CA 72.4 and CA 125 determination, separately and in combination, for diagnosing ovarian tumors in post-menopausal women with pelvic mass. The 299 patients recruited in this study underwent gynecological examination, plasma determination of CA 72.4 and CA 125, and laparotomy with histological definition of pelvic mass. CA 72.4 assay values were under 3.9 U/ml in 194 cases (70.8%); values ranged from 3.9 to 4.5 U/ml in 7 cases (2.5%) and were greater than 4.5 U/ml in 73 cases (26.6%). CA 72.4 assay was positive (>4.5 U/ml) in 56 cases (57.1%) of malignant ovarian pathology, in 4 cases (25%) of malignant extra-ovarian pathology as well as in 9 cases (7.1%) of benign ovarian pathology and in 4 cases (11.8%) of benign extra-ovarian pathology. With a cut-off at 3.9 U/ml, CA 72.4 showed a specificity of 91.3% and a sensitivity of 62.2%, whereas with a cut-off at 4.5 U/ml specificity was 92.9% and sensitivity 57.1%. Results of CA 125 assay for diagnosing a pelvic neoplasia (ovarian or extra-ovarian), showed a specificity of 85.3% and sensitivity of 68.8%. The agreement of the two markers (CA 125 and CA 72.4) as negative or positive shows a specificity of 77% and a sensitivity of 84.7% for ovarian cancer and a specificity of 73.5% and sensitivity of 75% for the diagnosis of pelvic neoplasias.

Prospective multicenter study on CA 125 in postmenopausal pelvic masses.

The purpose of this study was to determine the diagnostic value of CA 125 in comparison with transabdominal ultrasound (US) in the evaluation of postmenopausal women with pelvic mass to detect malignant epithelial ovarian tumors. Postmenopausal patients with pelvic mass were studied with gynecologic examination, US and CA 125 determination. Three hundred eighty-eight patients were entered in the study. According to stratification based on US (probably benign, equivocal, possibly malignant) and CA 125 (< 35 U/ml, negative; between 35 and 65 U/ml, borderline; > 65 U/ml, positive), 290 patients were considered eligible for surgery. Specificity, sensitivity, positive and negative predictive value, and accuracy of US and CA 125 were calculated with respect to histological examination. Out of 290 operated patients, 134 had a benign ovarian pathology, 34 had extraovarian benign pathology, 106 had an ovarian malignancy, and 16 presented with an extraovarian malignant pathology. The results according to ovarian malignant pathology were as follows. CA 125 (> 65 U/ml): Specificity, 92.5%; sensitivity, 71.7%; accuracy, 83.3%. CA 125 (> 35 U/ml): Specificity, 82.0%; sensitivity, 78.3%; accuracy, 80.4%. US: Specificity, 77.6%; sensitivity, 84.9%; accuracy, 80.3%. Combination of US and CA 125 (> 65 U/ml): Specificity, 96.1%; sensitivity, 91.7%; accuracy, 94.3%. Determination of CA 125 is a highly specific method in predicting ovarian cancer in postmenopausal women with a pelvic mass. The association with US significantly improves the overall accuracy and may support therapeutical decision making by distinguishing between a significant percentage of women most likely to benefit from prompt intervention and women who may be managed following minor surgical diagnostic approach, such as fine-needle aspiration.

The role of sonographically guided aspiration in the clinical management of ovarian cysts.

This study was undertaken to verify the role of fine-needle aspiration (FNA) followed by cytologic examination as a possible alternative to surgery in case of cystic pelvic masses. From January 1988 to March 1989, 204 patients with a proven cystic pelvic mass underwent FNA under sonographic guidance. In 20 cases the aspiration was performed transvaginally. Thirty-six patients were postmenopausal. In all cases the aspirated fluid was collected for cytologic evaluation. Other than one case of persistent hematuria, no complications occurred. The overall recurrence rate, verified 3 months from FNA, was 65%. Fifty-two per cent of patients developed a new cyst after a complete aspiration. Fifty-three patients underwent a laparotomy, allowing a comparison between cytologic and histologic patterns. The sensitivity of cytologic examination of aspirated fluids was 40% (3 of 5 malignancies were missed) and the specificity was 100% (no false positives were observed). We conclude that FNA might be proposed in young women with a unilocular ovarian cyst to avoid a surgical procedure. In postmenopausal women with a unilocular cystic mass 5 cm or less, FNA may be considered as an important step in the diagnosis. In all instances the ultrasonographic appearance of the cyst (echo texture and regularity of wall) and the characteristics of aspirated fluid are the most important findings. When the aspirated fluid contains mucus or blood, or when a complex mass is present, exploratory laparotomy or a laparoscopy is recommended.