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Genellikle iyon odaları; içi hava eşdeğeri gaz ile dolu, dış duvarın iç yüzeyi iletkenliği sağlamak amacıyla karbon veya grafitle kaplı ve merkezi iki elektrottan oluşmaktadır. Eksternal radyoterapide hedefe istenilen dozun verilebilmesi için iyon odası kullanılarak doz ölçümü yapılmalıdır. Radyoterapide kullanılan ışınların doz ölçümünde, çeşitli dozimetri protokolleri tarafından Farmer tipi silindirik iyon odası tavsiye edilmektedir. İyon odalarının duyarlı hacmi 0,01 cc ile 0,6 cc arasında değişmektedir. Bu çalışmada 0,6 cc aktif hacme sahip iyon odasının duvar materyali 0,43 mm kalınlığa sahip grafit duvar elektrotu ve alüminyum merkez elektrotu ile imal edilmiş. Sun Nuclear marka SNC 600c silindirik iyon odası kullanılmıştır. Clinac IX marka lineer hızlandırıcı cihazında 6 ve 15 MV foton ışınlarında iyon odasının çeşitli dozimetrik parametrelere bağlı yanıtı incelenmiştir. Sonuç olarak SNC 600c marka iyon odasının her iki foton enerjisinde de doza bağlı yanıtının doğrusal olduğu görülmüştür. İyon odasının voltaja bağlı değişimde, üreticinin tavsiye ettiği 300 Volt ve üzerindeki değerlerde her iki foton enerjisi için %1’in altında bir fark görülmüştür. Her iki foton enerjisi için iyon odasının yanıtı doz hızından ve enerjiden bağımsızdır. Böylece SNC 600c Farmer tipi silindirik iyon odasının yüksek enerjili fotonlar ile yapılan radyasyon ölçümünde kullanılan dedektörlerin sahip olması gereken özellikleri taşıdığından, mutlak doz ölçümünde kullanılabileceği doğrulanmıştır., Generally, ion chambers consists of an outer wall and a central two electrodes, filled with air equivalent gas, and an inner surface covered with carbon or graphite to ensure conductivity. In external radiotherapy, dose measurement using ionazation chambers is required to deliver the desired dose to the target. For dose measurement of rays used in radiotherapy, Farmer type cylindrical ionazation chamber is recommended by various dosimetry protocols. The sensitive volume of the ionazation chambers varies between 0.01 cc and 0.6 cc. In this study, the wall material of the ionazation chamber with an active volume of 0.6 cc was fabricated with a graphite wall electrode with a thickness of 0.43 mm and an aluminum center electrode. In the Clinac IX brand linear accelerator device, the response of the ionazation chamber depending on various dosimetric parameters was investigated in 6 and 15 MV photon beams. As a result, it was observed that the dose-dependent response of the SNC 600c brand ionazation chamber was linear at 6 and 15 MV photon energies. In the voltage-dependent change of the ionazation chamber, a difference of less than 1% was observed for both photon energy at the manufacturer's recommended values of 300 Volts and above. The response of the ionazation chamber for both photon energies is independent of dose rate and energy. Thus, it has been confirmed that the cylindrical ionazation chamber of the SNC 600c farmer type can be used in absolute dose measurement, as it has the characteristics that detectors used in radiation measurement with high-energy photons should have.

Various radiotherapy planning methods for T1N0 laryngeal cancer have been proposed to decrease normal tissue toxicity. We compare helical tomotherapy (HT), linac-based intensity-modulated radiation therapy (IMRT), volumetric-modulated arc therapy (VMAT), and 3-D conformal radiotherapy (3D-CRT) techniques for T1N0 laryngeal cancer. Overall, 10 patients with T1N0 laryngeal cancer were selected and evaluated. Furthermore, 10 radiotherapy treatment plans have been created for all 10 patients, including HT, IMRT, VMAT, and 3D-CRT. IMRT, VMAT, and HT plans vs 3D-CRT plans consistently provided superior planning target volume (PTV) coverage. Similar target coverage was observed between the 3 IMRT modalities. Compared with 3D-CRT, IMRT, HT, and VMAT significantly reduced the mean dose to the carotid arteries. VMAT resulted in the lowest mean dose to the submandibular and thyroid glands. Compared with 3D-CRT, IMRT, HT, and VMAT significantly increased the maximum dose to the spinal cord It was observed that the 3 IMRT modalities studied showed superior target coverage with less variation between each plan in comparison with 3D-CRT. The 3D-CRT plans performed better at the Dmax of the spinal cord. Clinical investigation is warranted to determine if these treatment approaches would translate into a reduction in radiation therapy-induced toxicities. (C) 2016 American Association of Medical Dosimetrists.

This study describes the early clinical results and dosimetric parameters of intensity-modulated radiation therapy (IMRT) using a tomotherapy device in patients with primary bilateral synchronous breast cancer (PSBBC).Fourteen patients with bilateral breast cancer were treated with tomotherapy between January 2011 and October 2014. The treatment planning objectives were to cover 95% of the planning target volume using a 95% isodose, with a minimum dose of 90% and a maximum dose of 107%. The organs at risk (OAR), such as the lungs, heart, esophagus and spinal cord, were contoured. Acute toxicity was recorded during and after radiation therapy.The advantages included better treatment conformity with lower dosages to minimize the risk to susceptible organs, such as the lungs, heart and spinal cord. There was improved coverage of the planning target volume, including the regional nodes, without any field junction problems. The median homogeneity index was 0.13 and the median conformity index 1.32. The median V20, V15, V10 and V5 for the total lungs were 18.5, 23.3, 24.2 and 60%, respectively. Skin acute toxicity was grade 1 in 72% and grade 2 in 14% of the patients. Esophageal acute toxicity was grade 1 in 43% of the patients.Tomotherapy delivers treatment that is well-tolerated, with high homogeneity and coverage indexes and the capability to reduce the irradiation dose received by the lungs and heart in PSBBC patients. This technique is therefore feasible and safe for the treatment of bilateral breast cancer.

Objectives/Hypothesis: One of the most common acute side effects of irradiation is xerostomia, which results from damage to the salivary gland cells by direct ionization. Resveratrol is a natural compound with profound anti-inflammatory and antioxidant properties. The purpose of the present study was to investigate the potential protective effects of resveratrol on injury to the salivary glands of rats that were exposed to total body irradiation. Study Design: An experimental study at the Inonu University School of Medicine. Methods: Twenty-nine female rats were randomized into four groups: group 1, high-dose (100 mg/kg) resveratrol group (n = 7); group 2, low-dose (10 mg/kg) resveratrol group (n = 7); group 3, control (vehicle) rats (n = 7); and group 4, sham-irradiation group (n = 8). The medications were administered as single doses, and the rats were exposed to total body irradiation 24 hours after the treatment. The animals were sacrificed the following day, and the parotid and submandibular glands were excised. Salivary gland histology and the tissue levels of glutathione (GSH), nitric oxide (NO), and malondialdehyde (MDA) were investigated. Results: The rats in group 1 showed significantly decreased acinar loss and less ductal damage and cell necrosis than those of the control group (P < .05). Antioxidant GSH levels were significantly increased by high doses of resveratrol treatment. The tissue activities of MDA in both the parotid and submandibular glands were significantly reduced in group 1. Low-dose resveratrol treatment did not significantly alter the tissue levels of MDA. Conclusions: Resveratrol at relatively high doses can reduce the irradiation-dependent salivary gland damage, suggesting that this natural antioxidant may be effectively used to lessen the side effects related to salivary gland dysfunction that is induced by irradiation. Laryngoscope, 2012

In this study, the dosimetric effects of the Tomotherapy, noncoplanar and coplanar IMRT plannings were evaluated for the total scalp irradiation. Tomotherapy based and linac based IMRT plans were compared for 61 years old female patient with multipl myeloma. Two different linac based IMRT plans which are coplanar and noncoplanar were performed for total scalp irradiation. 20 Gy was given to the PTV volume. Firstly, homogeneity index and conformity index values were calculated for PTV. Secondly, the doses of organ at risk (OaR) which are lenses, brain, brainstem and parotid glands were dosimetrically evaluated. While, tomotherapy plan was more homogenous, noncoplanar plan was more conformal than the others. Our study figure out that the OaR doses can be decreased by using tomotherapy based IMRT. However, the treatment time was increased when the tomotherapy based IMRT used for treatment. Tomotherapy based IMRT can be used for total scalp irradiation with respect to OaR. Keywords: IMRT, tomotherapy, coplanar, noncoplanar, OaR