Biomedical subjects

K Oysul

Publications and source records attributed to K Oysul.

8 recordsLinked to original sources

PubMed2006

Evaluation of scatter dose of dental titanium implants exposed to photon beams of different energies and irradiation angles in head and neck radiotherapy.

OBJECTIVES: In this study, quantification of backscatter doses between scattering titanium dental implant and the thermoluminescent dosimeter (TLD(100)) radiation detector at axial beam irradiation-angle range of 0-90 degrees in head and neck radiotherapy is done to evaluate irradiation angle dependency of dose enhancement contributing to osteoradionecrosis. METHODS: A cylindrical titanium dental implant with diameter of 4 mm and length of 9 mm was implanted into a specially-designed human mandible phantom with a TLD100 chip placed on the buccal site and irradiated with 6 MV X, 25 MV X and Co-60 gamma sources at 19 different irradiation angles. RESULTS: Dose enhancement on a buccal site of the titanium implant depends on the incident beam angle. At angles of 65 degrees, 60 degrees and 40 degrees the maximum detected scatter doses over the titanium implant are 36%, 32% and 23% for Co-60 gamma, 6 MV X-ray and 25 MV X-ray, respectively. The dose enhancement at different beam angles was less pronounced in 25 MV X and more pronounced in Co-60 gamma irradiation. CONCLUSIONS: For the different radiation beams studied, the irradiation angle between scattering titanium dental implants and the central axis does not significantly affect the total dose that may lead to osteoradionecrosis of the mandible.

Cranial Irradiation↗

PubMed2004

Spermatocele: a rare complication of rectal surgery and radiotherapy. Case report.

A 47-year-old man developed a presacral mass after abdominoperineal resection, which is combined with pre and postoperative radio-chemotherapy for carcinoma of the rectum. CT-guided biopsy and cytological examination of the mass revealed no malignancy but spermatocele, which is a very unusual complication of rectal surgery.

Biopsy, Fine-Needle↗

PubMed2004

Muir-Torre syndrome presenting with ileus: a case report.

The Muir-Torre syndrome is characterized by cutaneous neoplasms and visceral malignancies. At least one sebaceous adenoma, epithelioma or carcinoma and at least one internal malignancy are required to make a reliable diagnosis. According to medical literature only two cases of Muir-Torre syndrome with jejunal carcinoma have been reported to date and there is no reported case with intestinal obstruction. Here, we report an unusual case of jejunal carcinoma presenting with ileus.

Humans↗

PubMed2004

Experimental lens-sparing optimization in therapeutic orbital irradiation with electron beams.

There has been a number of approaches in the literature for therapeutic malignant and benign orbital irradiation. All techniques intend to deliver a homogenous dose to the orbital and retroorbital target volume while sparing the lens of excessive dose. In this experimental lens-sparing study, 4 MeV and 12 MeV anterior electron irradiation has been used with cerrobend shielding circular blocks of varying diameter and thickness placed on a thin Mylar at the distal tip of the electron applicator to spare the lens. The first phase of the study in water phantom has been designed to determine the shield thickness and diameter constant for 4 MeV and 12 MeV electron beams. After optimizing the lens dose by water phantom, the second phase of our study has been designed to measure doses at lens and other specific localizations in randophantom under same conditions with 4 MeV and 12 MeV electron beams. By this technique lens accumulated 18.56% of prescribed dose and lateral aspects of the lens received 44.59% of the prescribed dose in 4 MeV electron irradiation, whereas this was 13.86% and 44.80%, respectively in 12 MeV electron irradiation. The technique used is found to be an extremely simple and effective technique allowing an easier setup with excellent dose distribution characteristics with lens sparing applicable to orbital irradiation practice.

Electrons↗

PubMed2003

Evaluation of dose homogenization and radiation carcinogenesis risk in total body irradiation for bone marrow transplantation.

The purpose of this study is to report on the dose homogeneity in total body irradiated patients undergoing Bone Marrow Transplantation (BMT), and carcinogenic risk in surviving patients. Between 1987 and 2001, 105 patients received hyperfractionated (6 fractions in 3 days) 12 Gy Total Body Irradiation (TBI) in our institution with lateral opposed fields. All the patients had measurements with thermoluminiscence dosimetry (TLD100) placed on seven bilateral body sites in vivo, controlled by the randophantom measurements to verify reasonable dose homogeneity achievement. The comorbid effects in the whole TBI conditioning group with at least three months post BMT follow-up were noted and surviving patients who had a minimum 5-year and maximum 14-year follow-up (median 7.8 years) have been evaluated for carcinogenic radiation risk on the basis of tissue weighting factors as defined by ICRP 60. Reasonable dose homogeneity by lateral opposed beam TBI has been obtained in all 105 patients in whom lateral TLD100 measurement means were within +5% of the planned doses. Calculated carcinogenesis risk factor was 11.34% for males and 12.40% for females, and no second-cancer has been detected whilst radiation-induced 5 cataracts and 10 interstitial pneumonia comorbidities were noted. Dose homogenization can be well achieved for hyperfractionated lateral-beam TBI with acceptable comorbidities and estimated second-cancer risk is significant but relatively low compared to the risk from the clinical indications for TBI.

Bone Marrow Transplantation↗

PubMed2002

Evaluation of radiation carcinogenesis risk in vertebral hemangioma treated by radiotherapy.

The purpose of this study is to report carcinogenesis risk factor evaluation in vertebral hemangioma patients treated by radiotherapy. Between 1975 and 1995, 29 patients received 20-30 Gy total irradiation dose using conventional fractionation scheme. All the patients had measurements with thermoluminescent dosimeters (TLD 100 ), placed on multiple randophantom sites in vivo within the irradiated volume, to verify irradiation accuracy and calculate carcinogenesis risk factor. Twenty nine still-alive patients who had a minimum 6-year and maximum 26-year follow-up (median 14.34 years) have been evaluated by carcinogenic radiation risk factor on the basis of tissue weighting factors as defined by International Commission on Radiological Protection Publication 60. Reasonable pain relief has been obtained in all 29 patients. Calculated mean carcinogenesis risk factor is 0.6% for single irradiation portals and 0.9% for double irradiation portals in the whole group, whilst no secondary cancer has been detected. Radiotherapy is an effective treatment modality in relieving pain of vertebral hemangioma patients. Estimated secondary cancer risk factor for this benign neoplasm irradiation is not as high as can be feared.

Adult↗

PubMedDate not supplied

Retinoic acid and intestinal wound healing in intra-operatively irradiated rat.

AIM: This study was undertaken to assess the effect of intra-operative radiotherapy on intestinal wound healing and prevention of its side effects by retinoic acid. MATERIALS AND METHODS: Thirty Spraque-Dawley rats were divided into 3 groups of (n = 10). All the groups had laparatomies and terminal ileum exteriorization. Group I was the control group with no irradiation and no anastomosis; group II had both irradiation and anastomosis and group III rats had peroral retinoic acid conditioning and irradiation + anastomosis. On the seventh postoperative day, tensile strength and intestinal elongation measurements were to evaluate the effect of retinoic acid on wound healing. RESULTS: Compared to the non-retinoic acid conditioned group, the retinoic acid conditioned group had statistically significant higher tensile strength and lower intestinal elongation values, revealing better wound healing. CONCLUSION: Peroral retinoic acid supplement administration has a preventive effect on radiation-induced wound-healing inhibition in intra-operative abdominopelvic irradiation and anastomoses.

Anastomosis, Surgical↗

PubMedDate not supplied

Split-course radiotherapy with or without concurrent or sequential chemotherapy in non-small cell lung cancer.

In our department we designed a three-armed study to compare the effects of sequential and concurrent chemoradiotherapy in locally advanced non-small cell lung cancer. Each treatment arm consisted of 15 patients with histologically confirmed stage III non-small cell lung cancer. In group 1, the main treatment approach was split-course radiotherapy alone. In group 2, 6 mg/m2 of cisplatin was applied daily and concurrently with split-course radiotherapy. In group 3, two cycles of etoposide, ifosfamide, and cisplatin chemotherapy, which ended three weeks before split-course radiotherapy, was applied. Overall response rates were 40%, 66%, and 53% in groups 1, 2, and 3, respectively. Median survival was 10, 11, and 10 months for groups 1, 2, and 3 respectively. Results are discussed in the light of the literature.

Antineoplastic Combined Chemotherapy Protocols↗