OBJECTIVE: To evaluate the necessity of weekly monitoring by means of leukocyte and platelet counts of patients with head and neck, chest, and pelvis cancer submitted to conventional radiotherapy. MATERIALS AND METHODS: A hundred and one adult patients with cancer of head and neck (n = 11), chest (n = 35) and pelvis (n = 55), submitted to radiotherapy were assessed by means of leukocyte and platelet counts on a weekly basis, with a comparison between the results before and during the treatment and in correlation with the area treated, patient's sex and age group. RESULTS: The most significant decrease in leukocytes was observed in the fourth week, when lymphocytes, total leukocytes, neutrophils, monocytes and platelets presented a decrease of 53.5%, 26.8%, 19.4%, 22.2% and 14.6%, respectively, in comparison with the values found before the beginning of the therapy. Geometric means for pelvis during the treatment were lower than those for chest, and head and neck. Lymphocytes demonstrated to be more sensitive to radiation therapy. No alteration was found in leukocyte or platelet counts in correlation with patients' sex or age. CONCLUSION: Based on the results of the present study, weekly leukocyte and platelet counts do not seem to be useful in the assessment patients submitted to conventional radiotherapy for localized cancer.

Keywords: Leukocyte count, Complete blood count, External beam radiotherapy, Radiotherapy toxicity

OBJECTIVE: The objective of the present study was to evaluate both immediate and late effects of fractionated cobalt-60 teletherapy over the mean percentage of empty osteocyte lacunae in rats mandibles. MATERIALS AND METHODS: The animals sampling (n = 45) was divided into three groups with 15 specimens each: group 1 - submitted to fractionated teletherapy (60 Gy) and sacrificed following the last irradiation dose; group 2 - the specimens were submitted to the same procedure as group 1, however were sacrificed 30 days after finishing radiotherapy; group 3 - non-irradiated specimens, control group. The radiotherapy protocol consisted of a course of 30 radiotherapy sessions, fractionated in 2 Gy/day-doses, totalling 60 Gy. After specimens perfusion with 4% paraformaldehyde, the left hemimandibles were histologically processed and 5 mm serial sections were hematoxylin-eosin stained. Duplicate calculation of the mean percentage of empty osteocyte lacunae was performed in the areas adjacent to the first and second molar roots with the Image Tool software. RESULTS: The analysis of variance supplemented with the Turkey's multiple comparison test indicated that irradiated groups 1 and 2 showed no difference, presenting higher rates of empty osteocyte lacunae (p = 0.005) in comparison with the control group. CONCLUSION: Fractionated cobalt-60 teletherapy causes an increase in the number of osteoplasts in bone tissues of rats' mandibles.

Keywords: Radiotherapy, External beam radiation therapy, Late effects, Radiation damage, Osteoradionecrosis, Rats

OBJECTIVE: The present study was aimed at evaluating the occupational exposure of nursing staff in charge of inpatients undergoing 131I therapy during 11 years. MATERIALS AND METHODS: The exposure situations were classified according to a questionnaire answered by three nursing attendants, correlating the procedures with activities, distances and amount of time in the iodotherapy room. Records of received doses by two types of dosimeters were evaluated over two subsequent periods. In both periods the nursing attendants received instructions about radiological protection. RESULTS: In usual situations, their amount of time in the iodotherapy room was in compliance with the standard time established by the service. In unusual situations, where the patient needed assistance for mobility, the exposure period was above the standard. However, this exposure occurs casually (only one or two times a year). During the period between 1993 and 1999 (dosimetric films) there were ten dose records, all of them at record level. From 2000 to 2003 (thermoluminescent dosimeters) ten dose records were also obtained, with only one of them at the investigation level. During this study period, the mean 131I activity was doubled. CONCLUSION: Despite the increased levels of activity there was no significant increase in dose to nursing attendants.

Keywords: Occupational exposure, Effective dose, External individual monitoring, Iodo-therapy

OBJECTIVE: Our purpose was to verify the effect of changes in subject contrast, exposure time and radiation dose when different thicknesses of molybdenum (Mo) and rhodium (Rh) filters are used in mammography equipments. MATERIALS AND METHODS: Entrance skin exposure measurements were performed with an ionization chamber for different thicknesses of Mo and Rh filters. Average glandular dose was determined with a BR12 simulator (50% fat tissue and 50% glandular tissue) of different thicknesses (4 cm and 8 cm). Energies in the range of 24 to 34 kVp and Kodak MinR 2000 films were used. RESULTS: Results have evidenced data on subject contrast data, glandular dose and exposure time for different thicknesses of additional filters and different kVp values. These data have indicated an increase both in values of subject contrast and exposure time when filters thickness is increased. The glandular dose has presented a different behavior tendency for each case analyzed. Equations were defined to allow us to estimate subject contrast, glandular dose and exposure time for the cases studied. CONCLUSION: The results have made possible to define equations to assist with the evaluation of subject contrast and glandular dose behavior in simulators with 4 cm and 8 cm thicknesses and for Rh and Mo additional filters. In this way, it is possible to estimate the figure of merit (subject contrast/glandular dose ratio) to assist in the risk-benefit analysis of the cases studied.

Keywords: Mammography, Radiation exposure, External dosimetry

OBJECTIVE: To evaluate the role of computed tomography in the assessment of deep extension of squamous cell carcinoma of the external auditory canal. MATERIALS AND METHODS: In the period between May 1995 and December 2003 six patients with squamous cell carcinoma of the external auditory canal were submitted to computed tomography scan at "Hospital Heliópolis", São Paulo, SP, Brazil, including axial and coronal slices with soft tissue and bone algorithms. RESULTS: Thickening of the soft tissue of the external auditory canal was seen in all patients, bone erosion and invasion of the middle ear in five (83.3%), invasion of the mastoid and parotid gland in four (66.7%), invasion of the temporomandibular joint in three (50%), and invasion of the middle cranial fossa, carotid canal and cervical lymph node enlargement in two (33.3%) patients. CONCLUSION: Assessment of deep extension of squamous cell carcinoma of the external auditory canal using computed tomography is useful for clinical staging of the disease allowing better therapeutic planning for these patients.

Keywords: Squamous cell carcinoma, External auditory canal, Computed tomography