Faculty of Medicine
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Item type:Publication, DEDICATED HEAD AND NECK 18F-FDG PET/CT PROTOCOL IN DETECTING CERVICAL LYMPH NODE METASTASIS(2022); ; - Some of the metrics are blocked by yourconsent settings
Item type:Publication, A Treatment Planning Comparison of Two Different 3D Conformal Techniques for Irradiation of Head and Neck Cancer Patients(Association for Medical Physics and Biomedical Engineering, 2010-11-06); ; Petkovska, SonjaThe purpose of this treatment planning study was to compare two different three dimensional conformal irradiation techniques for head and neck cancer patients. For 33 patients with head and neck carcinoma, irradiated according to the classical technique, we computed and evaluated a second irradiation technique in order to optimize the treatment planning protocol. The classical technique, termed “electron-photon fields”, employed two lateral semi-fields (23 fractions) for irradiation of the upper part of the planning target volume that should receive 50 Gy (PTV50) and an anterior and posterior field for the lower part. After the 23rd fraction the lateral fields were reduced from the dorsal side (2 fractions), in order to exclude the spinal cord from them. At the same time the dose to the shielded part of the target volume was delivered with matched electron fields. Finally, after the 25th fraction, the high risk volume was irradiated to the desired dose with plan where the spinal cord was completely shielded. In the new technique, termed “oblique photon fields”, 4 oblique isocentric photon fields were used (25 fractions): two anterior fields that covered the entire target volume that should receive 50 Gy and two posterior fields that covered only half of the target volume in order to shield the spinal cord. Thus, the necessity for using electron fields is eliminated. We kept the plan for irradiation of the high risk planning target volume the same as in the classical technique. The prescribed dose per fraction in all plans was 2 Gy. In both techniques the plans were optimized to the same maximal point dose and the same dose to the spinal cord. The oblique fields plan showed better coverage and homogeneity of the PTV50, except for the patients with positive resection margins receiving postoperative radiotherapy (receiving 66 Gy), where the coverage did not differ significantly. The conformity in both techniques did not differ significantly. The mean dose to the parotid glands was significantly smaller with the oblique fields plan in case of patients with negative resection margins and when all the patients were treated as one group. The preferred treatment technique is thus the oblique photon fields technique, not only because of the superior dosimetric parameters, but also because of the absence of the electron fields which complicate the entire treatment process from dosimetric as well as practical aspect. - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Acute Mucosal Reactions in Patients with Advanced Head and Neck Cancer Treated with Concurrent Chemoradiotherapy(Association for Medical Physics and Biomedical Engineering, Skopje, Macedonia, 2010-11-06); ; ; We conducted a clinical study to analyze the acute reactions in the oral cavity and the oropharyngeal (OCOPH) mucosa in patients with advanced head and neck cancer (HNC) undergoing a definitive treatment consisted of 3-D conformal radiotherapy combined with concomitant chemotherapy. Twenty nine patients with HNC who were treated between February 2008 and October 2009 were included in the study. The median age was 55 years (range 29-70). The site distribution was as follows: oropharynx, 20.7%; hypopharynx, 41.4%; larynx, 37.9%. The radiation technique used for 3-D conformal radiotherapy was named “oblique photon fields” technique. The OCOPH mucosa as a critical normal tissue was delineated in every patient. Extraction of planning target volume (PTV50) from the volume of OCOPH mucosa led to formation of an OCOPH mucosa with extracted PTV50 (OCOPHEx mucosa). Acute mucosal reactions were recorded using Radiation Therapy Oncology Group (RTOG) grading system. The duration of a maximum grade of reaction was also recorded. A time intensity parameter, so-called Severity-Time Units (STU), quantifying the area under the acute reaction curve, was used to express the intensity of mucositis over time in every patient. Grade 3 acute mucosal reaction was manifested in 19 patients (65.5%). The median duration of confluent mucositis was 21 days (range 14-35). The STU less than 1000 mm2 and the STU more than 1500 mm2 was calculated in equal number of patients (9 patients, or 31.0%). Statistically significant difference in the distribution of the grade 3 reaction was found among patients with different site of the primary tumor (p = 0.003). Statistically significant difference was found between the grade of the acute mucositis and the volume of OCOPHEx mucosa, the dose in 50% of the volume of OCOPHEx (D50%, OCOPHEx) mucosa, and the mean dose to OCOPHEx mucosa (p = 0.02, p = 0.0002, p = 0.00001, respectively). The tested relation between STU and delineated volumes (PTV50 and OCOPHEx mucosa) showed the presence of statistically significant difference (p = 0.044 and p = 0.02, respectively). Statistically significant difference was also found between STU and the mean dose to OCOPHEx mucosa (p = 0.0003). Linear regression showed negative correlation between STU and the volume of OCOPHEx mucosa (r = - 0.7; p < 0.05). The incidence and the duration of confluent mucositis were significantly greater in patients with oropharyngeal primary lesions. The intensity in time of acute mucosal reactions was significantly higher in patients with the greatest PTV50 and in those with the smallest volumes of OCOPHEx mucosa.