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477 poster Post-operative radiotherapy for skin carcinoma
S 122
476
Posters
poster
Radiosensitivity of healthy individuals and of cancer patients. B, Biesaaa 1,2, C. Streffer 1 1Institute of Medical Radiobiology , University Clinics, Essen, Germany 2Laboratory of Radiation Biology, Centre of Oncology, Krakow, Poland Radiosensitivity of lymphocytes was compared between 10 healthy individuals and 16 patients with head and neck cancers with the micronucleus (MN) test, the micronucleus-centromere (MNC) assay and the comet assay lessen technique). The spontaneous rate and the values directly after X-rays (0.3 to 2.0 Gy) were measured. With the comet assay the residual DNA damage was measured after X-rays with 2 Gy and repair times of 60, 120 and 180 minutes. The mean age of the healthy donors was 49.8 and of the cancer patients 56.5 years with no significant difference (p=0.193). For the healthy persons the spontaneous rate of MN increased, of MNC decreased and the initial DNA damage (comet assay) increased with age significantly (r=0.877, 0,905, 0,819 respectively). Such correlation was not seen in the cancer patients. However, the cancer patients showed a significantly lower rate of MNC than the healthy individuals, which indicates an increased genomic instability in the lymphocytes of the cancer patients. The cancer patients showed a higher rate of MN after 1.0 and 2.0 Gy and the higher initial DNA damage (comet assay) after 0, 0.3, 1.0 and 2.0 Gy than the healthy persons. These differences were significant. Also the residual damage after 2.0 Gy X-rays was significantly higher in the cancer patients after 60, .120 and 180 minutes of repair time. These date show an increased radiosensitivity of the lymphocytes from cancer patients which is especially indicated by the comet assay measuring DNA repair. Also the increased genomic instability of the cancer patients is very interesting. 477
poster
Post-operative radiotherapy for skin carcinoma N. Angelovska, S. Aleksova Coseva, Z. Stefanovski Institute of Radiotherapy and Oncology, Skopje, Republic of Macedonia Purpose: Skin carcinoma can be managed by radiotherapy and surgery used as single treatment modalities, but in some cases combination of these two procedures is indicated. The aim of the study is to evaluate the results of postoperative radiotherapy of the skin carcinoma. Methods: A retrospective analysis of 29 pts consecutively treated between 1990 and 1996 was made. All pts were referred after initial surgery treatment. At the time of presentation none of them had clinical evidence of local or regional disease. Indication for further treatment was based on the histopathological findings of either the microscopic residual cancer or the proximity of the resection margin. Patients were treated using ortovoltage equipment or electron beam therapy. Prescribed doses ranged from 45 Gy to 60 Gy. Results: During the follow-up period (min. 42 months) there was evidence of one local failure (basal cell carcinoma) and there was no evidence of regional metastatic disease. Cosmetic results were good in most of the pts (24 pts) and satisfactory with the others. Conclusions: A recommendation for the optimal treatment approach is to be made for each patient. Regarding to the results of the local control and minimal damage of the normal tissues, postoperative radiotherapy is considered to be an effective complementary treatment modatity. 478
poster
Skin cancer in Macedonia B. Angelovska, L. Maneva -Kostovska, N. Angelovska, S. Aleksovska, C. Tolevska Radiotherapy and Oncology, radiotherapy, Skopje, Macedonia Introduction: Cancer of the skin ( basal - BCC and sqamous cell carcinoma - SCC) are the most common forms of non-melanoma skin cancer. Material and methods: A, period of two years from January 1990 to December 1992, a total of 385 consecutively treated and histologicaly confirmed SCC and BCC skin cancers were treated at Institute of Radiotherapy and Oncology (IRO), Skopje and were analized retrospectively. Findings: Of the 385 patients, there were 223 (58%) men and 162 (42%) women. There were 288 (75%) BCC and 97 (25%) SCC. Men comprised 76% of the basal cell population and 54% of the squamous cell patients. The age distribution for BCC and SCC patients are similar with the peak incidence occurring from age 60 to 70 and the range extending from the third to the ninth decade. 91% of the BCC are located on the head with 45% occurring on the nose or in a periorbital location. 75% of the SCC are located on the head with 48% on the ear, scalp or nose. 93,5% of the skin cancer is located on the
exposed (uncovered) parts of the skin. Radiotherapy was the initial treatment modality in 343/385 patients (89%) and 42/385 (11%) were treated after surgical excision. 331 of 385 patients remained free from local recurrence (86%), for BCC 226/288 patients (91%) and for SCC 73/97 (75%). Conclusions: Skin cancer is the most common neoplasm in our country. The most common ethiology of skin cancer is ultraviolet light light UV -B ( 290 - 320 nm) an agent to which we are all exposed. Besides ultraviolet lights influence and climatic conditions to whom, people are exposed, high temperature, humidity and structure of the air, spread of the wind, atmospheric pressure cause cancer as well. The superficial nature of the skin cancer makes it readily accessible to examination thus offering a potential for early diagnosis and therapy, radiotherapy is an excellent treatment modality for skin cancer. 479
poster
Response of different types detectors using narrow beam measurement T. Fuiisaki I H. Saitoh 2, S. Abe 1, T. Inada 1 l lbaraki Prefectural University of Health Sciences, Radiological Sciences, Ibaraki, Japan 2Tokyo Metropolitan University of Health Sciences, Radiologic Sciences, Tokyo, Japan Purpose:To evaluate difference of response by kind of the detectors, PDDs were measured using several kinds of detectors practically. The absorbed dose of these detec-tion materials in water was also calculated using Monte Carlo simulation. Methods: The PDDs on the central axis of 10 MV narrow x-ray beam were measured using several kinds of detectors such as ionization chambers, silicon diode detectors and a film. The absorbed dose of these detection materials such as air-gas, silicon and photo-emulsion in water was also calculated using EGS4 Monte Carlo simulation. Measured PDDs and the calculated depth dose curves were normalized at 10 cm depth in water according to the recommendation. Results: It was shown that the plane-parallel ionization chamber should be used to the meas-urement in the buildup region for narrow beam dosimetry, and the response of diode de-tectors (silicon) and a film (photoemulsion) was higher than ionization chambers (air-gas) in deeper water and smaller fields. Conclusions: The dose distribution measurement is depend on the types of detectors because there is difference of response by the material and shape of sensitive volume of radiation detectors. 480
poster
The inhomogeneity of co-60 beam, in comparison with that, expected, by standard isodose curves G. Shehi, B. Do//aku, G. Avdia Department of Radiotherapy, Institute University Hospital Center Mother Teresa, Tirana, Albania Purpose: to show the incorrect values, coming up by use of 2 or more (at least one non coploanar) fields, during the calculation in our "ROCS" program, to improve the treatment of patients through elimination or/and reduction of it. Methods: 1. comparison of values given by isodose curves summing and those coming up from measurements, or/and, reading of values in monitor matrix. 2. the use of densitometry, to determine the zone of maximum gradient of cobalt beam. The presumed role of such uncertainty in above mentioned error. Conclusions: 1. the error arised from computer S calculations, consist mainly of the Dmax, values of the non-coplanar beam (NCB) which factors being projected onto the NCB Dmax points, results affected. Only the NCB Dmax, dose values are affected, the others, like isodoses, calc. points are unaffected. 2. our efforts to correlate the start-point of gradient of surface dose, after having explained it physically, with computer errors, giving the arguments for the necessity to avoid the use of periphedc part of cobalt beams. 481
poster
Comparison of lens dose in neurosurgical plans using Cerrobend blocks versus 80 - leaf and 120 - leaf Multileaf Collimators. B. Chesson Peter Maccallum Cancer Institute, Radiation Therapy, Melbourne, Australia Objective: Use of Multileaf Collimators (MLC's) allows efficient application of shielding to radiotheraputic procedures. Additionally, MLC's overcome
476
Posters
poster
Radiosensitivity of healthy individuals and of cancer patients. B, Biesaaa 1,2, C. Streffer 1 1Institute of Medical Radiobiology , University Clinics, Essen, Germany 2Laboratory of Radiation Biology, Centre of Oncology, Krakow, Poland Radiosensitivity of lymphocytes was compared between 10 healthy individuals and 16 patients with head and neck cancers with the micronucleus (MN) test, the micronucleus-centromere (MNC) assay and the comet assay lessen technique). The spontaneous rate and the values directly after X-rays (0.3 to 2.0 Gy) were measured. With the comet assay the residual DNA damage was measured after X-rays with 2 Gy and repair times of 60, 120 and 180 minutes. The mean age of the healthy donors was 49.8 and of the cancer patients 56.5 years with no significant difference (p=0.193). For the healthy persons the spontaneous rate of MN increased, of MNC decreased and the initial DNA damage (comet assay) increased with age significantly (r=0.877, 0,905, 0,819 respectively). Such correlation was not seen in the cancer patients. However, the cancer patients showed a significantly lower rate of MNC than the healthy individuals, which indicates an increased genomic instability in the lymphocytes of the cancer patients. The cancer patients showed a higher rate of MN after 1.0 and 2.0 Gy and the higher initial DNA damage (comet assay) after 0, 0.3, 1.0 and 2.0 Gy than the healthy persons. These differences were significant. Also the residual damage after 2.0 Gy X-rays was significantly higher in the cancer patients after 60, .120 and 180 minutes of repair time. These date show an increased radiosensitivity of the lymphocytes from cancer patients which is especially indicated by the comet assay measuring DNA repair. Also the increased genomic instability of the cancer patients is very interesting. 477
poster
Post-operative radiotherapy for skin carcinoma N. Angelovska, S. Aleksova Coseva, Z. Stefanovski Institute of Radiotherapy and Oncology, Skopje, Republic of Macedonia Purpose: Skin carcinoma can be managed by radiotherapy and surgery used as single treatment modalities, but in some cases combination of these two procedures is indicated. The aim of the study is to evaluate the results of postoperative radiotherapy of the skin carcinoma. Methods: A retrospective analysis of 29 pts consecutively treated between 1990 and 1996 was made. All pts were referred after initial surgery treatment. At the time of presentation none of them had clinical evidence of local or regional disease. Indication for further treatment was based on the histopathological findings of either the microscopic residual cancer or the proximity of the resection margin. Patients were treated using ortovoltage equipment or electron beam therapy. Prescribed doses ranged from 45 Gy to 60 Gy. Results: During the follow-up period (min. 42 months) there was evidence of one local failure (basal cell carcinoma) and there was no evidence of regional metastatic disease. Cosmetic results were good in most of the pts (24 pts) and satisfactory with the others. Conclusions: A recommendation for the optimal treatment approach is to be made for each patient. Regarding to the results of the local control and minimal damage of the normal tissues, postoperative radiotherapy is considered to be an effective complementary treatment modatity. 478
poster
Skin cancer in Macedonia B. Angelovska, L. Maneva -Kostovska, N. Angelovska, S. Aleksovska, C. Tolevska Radiotherapy and Oncology, radiotherapy, Skopje, Macedonia Introduction: Cancer of the skin ( basal - BCC and sqamous cell carcinoma - SCC) are the most common forms of non-melanoma skin cancer. Material and methods: A, period of two years from January 1990 to December 1992, a total of 385 consecutively treated and histologicaly confirmed SCC and BCC skin cancers were treated at Institute of Radiotherapy and Oncology (IRO), Skopje and were analized retrospectively. Findings: Of the 385 patients, there were 223 (58%) men and 162 (42%) women. There were 288 (75%) BCC and 97 (25%) SCC. Men comprised 76% of the basal cell population and 54% of the squamous cell patients. The age distribution for BCC and SCC patients are similar with the peak incidence occurring from age 60 to 70 and the range extending from the third to the ninth decade. 91% of the BCC are located on the head with 45% occurring on the nose or in a periorbital location. 75% of the SCC are located on the head with 48% on the ear, scalp or nose. 93,5% of the skin cancer is located on the
exposed (uncovered) parts of the skin. Radiotherapy was the initial treatment modality in 343/385 patients (89%) and 42/385 (11%) were treated after surgical excision. 331 of 385 patients remained free from local recurrence (86%), for BCC 226/288 patients (91%) and for SCC 73/97 (75%). Conclusions: Skin cancer is the most common neoplasm in our country. The most common ethiology of skin cancer is ultraviolet light light UV -B ( 290 - 320 nm) an agent to which we are all exposed. Besides ultraviolet lights influence and climatic conditions to whom, people are exposed, high temperature, humidity and structure of the air, spread of the wind, atmospheric pressure cause cancer as well. The superficial nature of the skin cancer makes it readily accessible to examination thus offering a potential for early diagnosis and therapy, radiotherapy is an excellent treatment modality for skin cancer. 479
poster
Response of different types detectors using narrow beam measurement T. Fuiisaki I H. Saitoh 2, S. Abe 1, T. Inada 1 l lbaraki Prefectural University of Health Sciences, Radiological Sciences, Ibaraki, Japan 2Tokyo Metropolitan University of Health Sciences, Radiologic Sciences, Tokyo, Japan Purpose:To evaluate difference of response by kind of the detectors, PDDs were measured using several kinds of detectors practically. The absorbed dose of these detec-tion materials in water was also calculated using Monte Carlo simulation. Methods: The PDDs on the central axis of 10 MV narrow x-ray beam were measured using several kinds of detectors such as ionization chambers, silicon diode detectors and a film. The absorbed dose of these detection materials such as air-gas, silicon and photo-emulsion in water was also calculated using EGS4 Monte Carlo simulation. Measured PDDs and the calculated depth dose curves were normalized at 10 cm depth in water according to the recommendation. Results: It was shown that the plane-parallel ionization chamber should be used to the meas-urement in the buildup region for narrow beam dosimetry, and the response of diode de-tectors (silicon) and a film (photoemulsion) was higher than ionization chambers (air-gas) in deeper water and smaller fields. Conclusions: The dose distribution measurement is depend on the types of detectors because there is difference of response by the material and shape of sensitive volume of radiation detectors. 480
poster
The inhomogeneity of co-60 beam, in comparison with that, expected, by standard isodose curves G. Shehi, B. Do//aku, G. Avdia Department of Radiotherapy, Institute University Hospital Center Mother Teresa, Tirana, Albania Purpose: to show the incorrect values, coming up by use of 2 or more (at least one non coploanar) fields, during the calculation in our "ROCS" program, to improve the treatment of patients through elimination or/and reduction of it. Methods: 1. comparison of values given by isodose curves summing and those coming up from measurements, or/and, reading of values in monitor matrix. 2. the use of densitometry, to determine the zone of maximum gradient of cobalt beam. The presumed role of such uncertainty in above mentioned error. Conclusions: 1. the error arised from computer S calculations, consist mainly of the Dmax, values of the non-coplanar beam (NCB) which factors being projected onto the NCB Dmax points, results affected. Only the NCB Dmax, dose values are affected, the others, like isodoses, calc. points are unaffected. 2. our efforts to correlate the start-point of gradient of surface dose, after having explained it physically, with computer errors, giving the arguments for the necessity to avoid the use of periphedc part of cobalt beams. 481
poster
Comparison of lens dose in neurosurgical plans using Cerrobend blocks versus 80 - leaf and 120 - leaf Multileaf Collimators. B. Chesson Peter Maccallum Cancer Institute, Radiation Therapy, Melbourne, Australia Objective: Use of Multileaf Collimators (MLC's) allows efficient application of shielding to radiotheraputic procedures. Additionally, MLC's overcome