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Lycopene in the Prevention of Gastrointestinal Toxicity of Radiotherapy

We conducted a study to investigate if lycopene could reduce gastrointestinal toxicity of abdominal and pelvic radiation in Wistar albino rats. Animals received either a control diet (Group 1), lycopene-supplemented diet (Group 2), control diet and radiation (Group 3), and lycopene-supplemented diet plus radiation (Group 4). In Groups 2 and 4, the rats received 5 mg/kg/day lycopene for 10 days. In Groups 3 and 4, the rats received single fraction 8 Gy abdominal and pelvic radiation (RT) on Day 10. Study endpoints included weight loss, diarrhea, duration of diarrhea, survival, and an oxidative stress marker, plasma level of thiobarbituric acid reactive substance (TBARS). The rats receiving RT only had significantly higher weight loss rate compared to the lycopene plus RT group (P = 0.001). Plasma TBARS levels after RT were also significantly higher in the RT only group compared to lycopene plus RT group (P = 0.001). In conclusion, lycopene supplementation significantly reduced the weight loss and prevented oxidative stress in rats treated with abdominopelvic radiation.

Radiotherapy-induced decreases in substance P levels may potentiate melanoma growth.

Substance P, a member of the tachykinin family, is expressed in primary invasive malignant melanomas, metastatic melanomas, melanomas in situ, atypical naevi, and spindle and epithelioid cell naevi. The role of substance P in cancer development and progression is not clear. Radiotherapy, which is used extensively in the treatment of malignancies, alters substance P levels. It is, however, not known whether radiotherapy affects substance P levels in melanomas or in the tumor microenvironment. Given the fact that melanomas express substance P, possible radiation-induced changes in substance P content may underlie their radio-resistance. Hence, the aim of the present study was to determine the effects of radiotherapy on the growth of B16F10 melanomas as well as on the tumor and systemic expression of substance P. In vivo exposure of tumor-bearing C5BL/6 mice to ionizing radiation (45 Gy administered in three fractions) arrested tumor growth for three weeks and induced 3-fold increases in survival, as well as decreasing substance P levels in primary tumors and the surrounding skin. Although radiotherapy was applied locally (1 x 1 cm) at the mid-flank region of the animal, it also induced systemic changes in the levels of substance P. Specifically, radiotherapy decreased substance P levels in skin distant from the radiation field as well as in the lungs and adrenals. In order to understand the significance of this effect, B16F10 cells and cells made from metastatic lesions (B16LNAD cells) were treated with substance P. Substance P inhibited the growth of B16F10 and B16LNAD cells and further potentiated the inhibitory effects of radiotherapy. These findings demonstrate for the first time that substance P inhibits melanoma growth, and that radiotherapy-induced decreases in substance P levels may underlie the radio-resistance of melanomas.

Assessment of setup accuracy in patients receiving postmastectomy radiotherapy using electronic portal imaging

PurposeThe aim of this study was to investigate the setup accuracy for patients undergoing postmastectomy radiotherapy using electronic portal imaging.Materials and methodsTen patients undergoing radiotherapy via tangent (TG), supraclavicular-axillary (SA), and internal mammary (IM) fields were included. To explore the setup accuracy, distances between chosen landmarks were taken as reference parameters (RPs). The difference between measured RPs on simulation films and electronic portal images (EPIs) was calculated as the setup error.ResultsA total of 30 simulation films and 120 EPIs were evaluated. In the SA field, calculated RPs were lung length (LL), clavicle-field center perpendicular distance, and clavicle-field center transverse distance. The mean of the standard deviations (SDs) of the random errors (σ) for these parameters were 4.7, 7.3, and 7.6; and the SDs of the systematic errors (Σ) were 6.8, 4.4, and 13.5, respectively. In the TG fields, the calculated RPs were the central lung distance (CLD), maximum lung distance (MLD), and central soft-tissue distance (CSTD). In the medial TG field, the σ values for these parameters were 3.4, 3.6, and 4.1, respectively; and the σ values were 6.6, 2.6, and 3.4, respectively. In the lateral TG field, Σ values for the calculated RPs were 2.4, 3.2, and 3.3l, respectively; and the Σ values were 5.6, 3.6, and 4.8, respectively.ConclusionCLD, MLD, and CSTD in TG fields and LL in SA fields are easily identifiable and are helpful for detecting setup errors using EPIs in patients undergoing postmastectomy radiotherapy.

The environmental dose measurements of high dose Iodine-131 treated thyroid cancer patients during hospitalization period

Objective: We aimed to di erentiate ischemic heart failure (HF) from non-ischemic HF in patients presenting with non-acute onset exertional dyspnea using technetium-99m methoxyisobutylisonitrile 99m gated single photon emission tomography ( Tc-MIBI gSPET) imaging. Subjects and Methods: One hundred and seventy nine consecutive patients with exertional dyspnea without concomitant chest pain 99m referred to Tc-MIBI gSPET imaging were included in this study. All patients had a newly diagnosed HF with reduced ejection fraction (HFrEF). Imaging ndings were compared between ischemic HF and nonischemic HF groups. Results: Of the 179 patients, 127 had ischemic HF and 52 had non-ischemic HF. There was no di erence between ischemic and non-ischemic groups in terms of age, gender, body mass index, any smoking history, diabetes mellitus, history of hypertension and hyperlipidemia. Global dysfunction of left ventricle was more common in non-ischemic HF group than ischemic HF group (82.7% vs 41.7% respectively, P<0.001). Presence of severe (3+/4+) ischemia and large perfusion defect were higher in ischemic HF group compared to non-ischemic HF group (45.7% vs 15.4%, P<0.001 and 23.6% vs 3.8%, P=0.003, respectively). Summed stress score (SSS), summed rest score and summed di erence score were higher in ischemic HF group compared to non-ischemic HF group (P<0.001, P<0.001, and P=0.021, respectively). In multivariate analysis, absence of global dysfunction (P<0.001, OR=10.338, 95%CI: 3.93727.405) and SSS (P<0.001, OR=1.208, 95%CI: 1.090-1.339) were the independent predictors of ischemic HF. Absence of global dysfunction had 58.3% sensitivity and 86.7% speci city for diagnosis of ischemic HF at gSPET imaging in patients presenting with newly diagnosed HF and exertional dyspnea without concomitant chest pain (AUC=0.705, 95%CI: 0.632-0.771, P<0.001), whereas SSS>8 had 65.4% sensitivity and 75.0% speci city (AUC=0.732, 95%CI:0.661-0.795, P<0.001). Conclusion: Absence of global dysfunction and SSS on SPET imaging were the independent predictors of ischemic etiology of HF presenting with dyspnea without concomitant chest pain. These ndings had a low sensitivity, but acceptable speci city. Hell J Nucl Med 2016; 19(2): 147-154 Epub ahead of print: 22 June 2016 Published online: 2 August 2016Radioiodine mostly 131I is one of the oldest clinical radionuclide types which used widely spread in diagnosis and currently used in the treatment of both thyreotoxicosis and thyroid cancer. This is an integral part of differentiated thyroid carcinoma therapy [1,2]. For most thyroid cancer treatments, large doses of 131I are administered to ablate residual thyroid tissue and functional metastases from thyroid cancer. The success of thyroid ablation with 131I depends mainly on the mass of remaining thyroid tissue in the neck and the initial dose rate to this tissue [3]. The activity to be used for radioiodine therapy still remains subject to discussion at differentiated thyroid cancer (DTC) for ablation of postsurgical thyroid remnants, destruction of metastases and etc. While it is performed by either administering an empiric fixed dose or using dosemetry-guided activities [3]. There is a broad range of the conventional fixed activities of 131I recommended to be administered [4,5]. Normally, the activity is limited for safety reasons to around 7.4 GBq [6]. A summary on the use of fixed activities for the treatment of DTC can be found in a review articles [7-9]. The lesion-based dosemetry concept, mainly on the data of Maxon et al. [10,11], aims at improving the efficacy of the treatment by achieving an absorbed dose threshold of more than 300 Gy to remnants. Because of radiation safety considerations, application of large doses of 131I greater than 800 MBq requires patient hospitalization [12,13]. Most of the administered radioiodine not taken up by thyroid tissue will be excreted from the patient primarily by the kidneys, and consequently, the patient should be encouraged to drink freely to minimize dose to kidneys, bladder and gonads. So, a great majority of the administered activity will appear in the urine [2]. For most patients, 35%-75% of the administered dose is excreted within the first 24 h after dose administration [13,14]. The next most significant pathway is saliva. This will manifest in contamination of eating and drinking utensils, and pillow coverings (due to saliva excretion during sleep). Lesser pathways are sweat and faeces. The proportion of each (apart from urine) will vary widely [2]. Radiation contamination could be expected from patient’s urine, perspiration and saliva over the course of the isolation period. For this reason, patients should be considered as a potential source of radiation contamination, especially during the first 48 hours following administration [2]. When considering radiation safety precautions for attending personnel, members of the general public and patients in adjacent rooms, it is important to remember that 131I emits both negative β particles and prominent gamma photons. Iodine-131 is typical of a complex beta decay scheme with physical half-life of 8.05 days. There are five Volume 1 Issue 2 2016

The Calibration Process of OSL Detectors used for Staff and Patient Dosimetry in Hospital Environment

The optically stimulated luminescence (OSL-BeO) dosemeter is increasingly being used as a dosimetric technique in various fields such as medical dosimetry. According to our fixed dose protocol, the activities of 3.7-7.4 GBq I-131 source is used for thyroid carcinoma therapy. The in house calibration process for usage of OSL’s at hospital was arranged according to the encapsulated I-131. The measurement point was planned in three different radial distances from source free in air. The dose-rate measurement was done by Geiger-Muller (GM), and then three pieces of OSL was placed in the same positions for one hour. The inverse square law consistency was found (R2=0.99). The calibration coefficient was calculated. For determining the performance of OSL at different dose rates, it used for personnel and patient dosimetry. The average annual dose/2mon to the whole body for all staff by OSL were 0.80 mSv. After administration of 3.7 GBq (100 mCi) therapeutic dose to selected patients, the average pectoral dose was 97.5+32.6 mSv. This calibration process is helpful for confidence of OSL detectors used for dosimetry of staff and patients treated with high activity I-131.

SU‐E‐T‐222: Contribution Of In Vivo Dose Measurement To The Intensity Modulated Radiotherapy Technique In The Treatment Of Prostate Cancer

Purpose: The contribution of in‐vivo dose measurement of organs at risk by TLD and semiconductor detectors during Intensity‐modulated radiotherapy technique in treatment of prostate cancer was studied. Methods: Appropriate prostate cancer patients target and organs at risk contours that managed for IMRT planning were fusion on CT images of Rando phantom. For PTV1 and 2 the equally angel nine fields (within 200°− 160°)IMRT plans were designed using 6MV photon energy with 180cGy per fraction to total dose of 45 and 72Gy respectively. The point dose and two‐dimensional dose measurements for the quality control evaluation of IMRT plans were done and found in appropriate limits. The 3 sub‐slab of Rando phantom were re‐made from paraffin and rectum cavity was created in accordance with the probe for measuring rectal dose. Based on dosimetric method each dosimeter was selected and located on measurement region. Prostate IMRT plans were applied to the phantom. In‐vivo dose measurements were repeated several times by TLD and diode, obtained dose values for rectum and bladder compared with TPS. Results: Both semiconductor and TLD dose measurement values for bladder and rectum is generally in agreement with the TPS. The rectum dose measurement values were differing from TPS up to 30% in intense dose gradient regions. This is because when the coordinates of the reference points are in intense dose gradient regions, +/− 1 mm changes in position create +/− 3–10% difference between the calculated and measured doses. Conclusion: The intracavitary rectum and bladder probes used for brachytherapy dosimetry applications could be applicable in external radiation treatments. In‐vivo dosimetry has an important role in the quality assurance of radiotherapy, especially to preventing errors which may occur in every stage of treatment. In this context,for more complex treatment techniques like IMRT the traditional in‐vivo dosimetric methods using TLD and semiconductor diodes was found to be reliable.

SU‐E‐I‐48: Organ Dose Measurement and Calculation for Dedicated CT Used In Radiotherapy

PURPOSE To investigate the organ doses of patients undergoing to General Electric (GE) Light Speed RT computed tomography (CT) device by the measurement and calculation method. METHODS The head, thorax and pelvis regions of Rando phantom scanned with 120kV, 200 mA, and 2.5 mm thickness for helical and axial mode. TLD pairs were used for dose measurements in specified 10 organ locations. Each exam was repeated and the TL counts averaged for organs. TL count conversion to dose was done for each scanning parameters using CTDI dose measurement on CT phantom. On the other hand, for calculation of organ doses at the same scanning process IMPACT software was utilized by using CTDI-air (100 mAs) that measured by ion chambers in small and large window widths. CTDI-air (100 mAs) in small and large window widths was 26.43 mGy and 21.17 mGy respectively. The organ doses that obtained from software and those from TLD measurements were compared. RESULTS In each examination the organ doses were tailored as the in-field and out-field radiation. The in-field organ dose differences between TLD measurements and Impact software calculation by entering CTDI-air (100 mAs): In helical and axial head exam the dose differences for eye, brain and thyroid were 2.8, 1 and 13.3, and 8.2, -8.3 and 9.6 mGy respectively, in helical and axial chest exam the dose differences for heart, lung, liver and kidney 2.7, 15.3 1.1 and 7.3 and, 9.1, 6.5, 0.3 and 5.2 mGy respectively, in helical and axial pelvic exam the dose differences for bladder, prostate, uterus and testis -3.6, -5.1, 1.9 and -21.7, and -3, -3.2, 1.8 and -15.5 mGy respectively. CONCLUSION The availability of this program for organ dose calculations by measuring the CTDI-air value of the CT device that used in the radiotherapy would be considered valuable.