Measurement of radiation exposure in relatives of thyroid cancer patients treated with (131)I.

This work evaluates the radiological risk that patients treated with I for differentiated thyroid cancer could present to relatives and occupationally exposed workers. Recently, the International Atomic Energy Agency issued document K9010241, which recommends that patient discharge from the hospital must be based on the particular status of each patient. This work measures effective dose received by caregivers of patients treated with I at the Instituto Nacional de Cancerología, Mexico City. Thermoluminescent dosimeters were carried during a 15-d period by 40 family caregivers after patient release from hospital. Relatives were classified into two groups, ambulatory and hospitalized, according to the release mode of the patient, and three categories according to the individual patient home and transport facilities. Categories A, B, and C were defined going from most to least adequate concerning public exposure risk. Measurements were performed for 20 family caregivers in each group. The effective dose received by all caregivers participating in this study was found to be less than 5 mSv, the recommended limit per event for caregivers suggested by ICRP 103. In addition, 70 and 90% of ambulatory and hospitalized groups, respectively, received doses lower than 1 mSv. Caregivers belonging to category C, with home situations that are not appropriate for immediate release, received the highest average doses; i.e., 2.2 ± 1.3 and 3.1 ± 1.0 mSv for hospitalized and ambulatory patients, respectively. Results of this work have shown that the proper implementation of radiation protection instructions for relatives and patients can reduce significantly the risk that differentiated thyroid cancer patients treated with I can represent for surrounding individuals. The results also stress the relevance of the patient's particular lifestyle and transport conditions as the prevailing factors related to the dose received by the caregiver. Therefore, the patient's status should be the criterion used to decide his/her release modality. This work provides support to recommend the implementation of the "patient specific release criteria" in accordance with ICRP 94, IAEA Safety Report No. 63, and IAE document K9010241 A for patients treated with radiopharmaceuticals.

Radiosensitization of cervical cancer cells with epigenetic drugs hydralazine and valproate.

PURPOSE: To evaluate the radiosensitizing effects of the DNA methylation inhibitor hydralazine in combination with valproic acid, a histone deacetylase inhibitor in cervical cancer cells. MATERIALS AND METHODS: Cell viability assays were performed in the SiHa cervical cancer cell line treated with hydralazine and valproic acid for five days with and without cisplatin. Cell irradiation was performed using teletherapy (1.25 MV). RESULTS: Neither hydralazine, valproic acid or cisplatin as single agents increased the cytotoxicity from radiation, however, the combination of hydralazine with valproic acid at ten microM and one mM, respectively, did induce radiosensitization (p = 0.046). Interestingly, this effect was further increased with the triple combination of hydralazine, valproic acid, and cisplatin (p = 0.041), where cell viability decreased more than 50% as compared to radiation alone. CONCLUSIONS: The present results demonstrate that epigenetic drugs increase the efficacy of cisplatin chemoradiation in cervical cancer cells.

First-line chemotherapy with liposomal doxorubicin plus cisplatin for patients with advanced malignant pleural mesothelioma: phase II trial.

BACKGROUND: Chemotherapy based on platinum is the standard treatment for unresectable malignant pleural mesothelioma (MPM). Liposomal doxorubicin (LD) consists of pegylated phospholipid vesicles that encapsulate doxorubicin-enhancing liposome deposition in the tumour. We evaluated the toxicity profile and anti-tumour activity of cisplatin plus LD in untreated patients with MPM, as well as (99m)Tc-LD distribution in MPM lesions after chemotherapy administration. METHODS: A total of 38 patients with non-resectable MPM received LD 40 mg m(-2) and cisplatin 60 mg m(-2) every 21 days. Gamma camera images of (99m)Tc-LD were acquired to evaluate LD accumulation in measurable tumour tissue. The study was registered in Clinical Trials (NCT00886028). RESULTS: In all, 72% of patients were stage III and 28% were stage IV. Eighty four percent and 16% have high and low risk acording EORTC respectively. The median time to progression was 4.6 months (95% confidence interval (95% CI: 3.4-5.9 months), and median overall survival (OS) was 19.6 months (15.2-37.2 months). Patients that responded to chemotherapy treatment had better survival than patients who did not. Functional physical scales, dysnea, cough, and chest/arm pain demonstrated improvement. The accumulation ratio of LD in tumour and soft tissues vs liver was 0.78±0.16 and 0.29±0.09, respectively. After 1 h of administration, LD uptake in tumour tissue was higher than in soft tissue (P< 0.001). CONCLUSION: The combination of LD and cisplatin results in an active therapeutic regimen for unresectable MPM, with an acceptable toxicity profile and improvement in quality of life. (99m)Tc-LD showed higher levels of tumour uptake as compared with surrounding tissues.

Small animal PET scanner based on monolithic LYSO crystals: performance evaluation.

PURPOSE: The authors have developed a small animal Positron emission tomography (PET) scanner based on monolithic LYSO crystals coupled to multi-anode photomultiplier tubes (MA-PMTs). In this study, the authors report on the design, calibration procedure, and performance evaluation of a PET system that the authors have developed using this innovative nonpixelated detector design. METHODS: The scanner is made up of eight compact modules forming an octagon with an axial field of view (FOV) of 40 mm and a transaxial FOV of 80 mm diameter. In order to fully determine its performance, a recently issued National Electrical Manufacturers Association (NEMA) NU-4 protocol, specifically developed for small animal PET scanners, has been followed. By measuring the width of light distribution collected in the MA-PMT the authors are able to determine depth of interaction (DOI), thus making the proper identification of lines of response (LORs) with large incidence angles possible. PET performances are compared with those obtained with currently commercially available small animal PET scanners. RESULTS: At axial center when the point-like source is located at 5 mm from the radial center, the spatial resolution measured was 1.65, 1.80, and 1.86 mm full width at half maximum (FWHM) for radial, tangential, and axial image profiles, respectively. A system scatter fraction of 7.5% (mouse-like phantom) and 13% (rat-like phantom) was obtained, while the maximum noise equivalent count rate (NECR) was 16.9 kcps at 12.7 MBq (0.37 MBq/ml) for mouse-like phantom and 12.8 kcps at 12.4 MBq (0.042 MBq/ml) for rat-like phantom The peak absolute sensitivity in the center of the FOV is 2% for a 30% peak energy window. Several animal images are also presented. CONCLUSIONS: The overall performance of our small animal PET is comparable to that obtained with much more complex crystal pixelated PET systems. Moreover, the new proposed PET produces high-quality images suitable for studies with small animals.