جستجوی مقالات مرتبط با کلیدواژه « D conformal radiotherapy » در نشریات گروه « پزشکی »

The present study includes a qualitative analysis of skin entry exit doses and Integral doses (ID) utilizing various treatment planning strategies.
For this study, we have taken 20 patients suffering from medulloblastoma and planned for Craniospinal irradiation (CSI) with Helical Intensity Modulated radiation therapy HIMRT, Helical three dimensional conformal radiation therapy H3DCRT, and Volumetric modulated arc therapy VMAT treatment planning techniques on Accuray Radixact X9 and Elekta Synergy (Agility) linear accelerator.
Various dosimetric parameters like Dmax, Dmean, D80%, D50%, D30%, and D10% have been calculated for skin and skin_ring. Integral doses have been calculated for PTV-Brain and PTV-Spine, taking into consideration at least V95% (target coverage by 95% of the prescribed dose). Statistical analysis was done using SPS software version 22. Mean skin entry and exit doses were [HIMRT=7.07±0.703, H3DCRT = 7.87±0.958 VMAT=4.09±0.706]. For Phase-1mean integral dose for PTV_Brain and PTV_Spine was [HIMRT=11.37±4.458, H3DCRT=12.30±5.00, VMAT=7.21±2.990] and Phase-2 mean integral doses for GTV_Boost was [HIMRT=0.10±0.10   H3DCRT = 0.11±0.117 VMAT=0.03±0.067]. Skin entry exit doses and integral doses were observed to be highest in H3DCRT and then HIMRT. Meanwhile, VMAT plans show minimum entry exit doses and integral doses for Phase 1 and Phase 2.
This study concludes that VMAT treatment planning techniques showing less skin entry exit doses and integral doses compared with helical treatment planning techniques. Taking care of these factors can give better clinical outcomes in terms of less late side effects.

This study aimed to compare high-grade gliomas radiation therapy methods (high energy three-dimensional conformal radiation therapy [3D-CRT] vs. low energy intensity-modulated radiation therapy [IMRT]). 

Out-of-field photons resulting from 15- and 18-MV 3D-CRT and 6-MV IMRT techniques were measured with thermo-luminescent dosimeters in a head and neck homogeneous phantom. Moreover, the dose to the left and right eye lenses, parotid glands, the thyroid gland, and the tongue was determined for each of the treatment techniques. Additionally, the risk of secondary thyroid cancer was estimated according to the biological effects of ionizing radiation BEIR VII model.

Errors in the treatment planning system (TPS) increased with increasing distance from the field edge and varied in different treatment techniques. The 6-MV IMRT technique increased the photon dose to all of the organs. Further, the excess relative risk for thyroid cancer was obtained higher in the 6-MV IMRT technique than in the 15- and 18-MV 3D-CRT techniques, as the photon dose to the thyroid gland was higher.

Although 6-MV IMRT better improves local control and dose distribution than 3D-CRT, it increases the total dose equivalent in out-of-field organs independently of beam energy and exacerbates the risk of secondary thyroid cancer more significantly.

Most women with left-sided breast cancer are at an increased risk of heartmorbidity and mortality from the adjuvant radiotherapy due to an increase in heart absorbed dose during radiotherapy treatment. This study aimed to compare free-breathing intensity-modulated radiotherapy (FB-IMRT) and three-dimensional conformal deep inspiration breath-hold (3DCRT-DIBH) techniques in terms of the cardiac dose.

In total, 15 women with left-sided breast cancer underwent FB and DIBH computed tomography (CT) scans in the same supine position. For DIBH CT, 3D-CRT plans were created using two opposing wedged tangential fields and for FB-CT, 4-5 IMRT optimized tangential fields were created. All plans were evaluated using the dose-volume histogram. The data were analyzed in SPSS software version 20 (IBM, IL).

The FB-IMRT plans were more homogeneous and had more dose coverage and fewer hotspots, than the 3DCRT-DIBH plans; however, the planning target volume V95% was clinically acceptable for both techniques. Furthermore, the 3DCRT-DIBH plans were much faster and require fewer monitor units. A significantly lower mean dose of heart, left lung, left anterior descending coronary artery, right lung, and V10% left lung were observed in 3DCRT-DIBH plans, compared to FB-IMRT plans. Moreover, FB-IMRT plans showed a significant further dose reduction in heart V25% and V30%.

The majority of the patients with left-sided breast cancer who treated with the DIBH technique were getting sufficient benefits of radiotherapy, and DIBH was a comprehensive strategy for reducing cardiac doses during radiotherapy treatment.

Breast conserving surgery followed by adjuvant whole breast radiotherapy is the accepted treatment in early-stage breast cancer. Due to breast irregularities, it is difficult to achieve homogenous dose distribution with conventional techniques. Currently, it is possible to use varied breast irradiation techniques such as field-in-field (FIF) that is claimed to produce more homogenous distribution of doses within the target volumes while sparing the organs at risk, leading to a better treatment outcome. The present study aimed to compare the conventional and the FIF techniques dosimetrically.

Twenty patients with early-stage breast cancer underwent computed tomography. Two different treatment plans were created for each patient: the wedge-based (conventional) plan and the FIF plan. Dosimetric parameters and monitor units were compared with paired sample t-test.

FIF technique obtained significantly lower dose homogeneity index, lower maximum doses and higher median doses in PTV (P<0.05). Similarly, the conformity index, and mean doses were higher in the FIF technique but the differences were not significant (P>0.05). In ipsilateral lungs, FIF significantly reduced the maximum and mean doses (P<0.05), and showed a tendency to reduce V20 (P>0.05). In patients with left-sided breast cancer, minimum and maximum doses and V40 of heart were significantly decreased in FIF plans (P<0.05). Doses to the contralateral lungs did not differ significantly.

These results along with significantly less monitor units required for therapy in FIF suggest that this technique may be more advantageous during breast irradiation.

  Orbital radiotherapy (RT) is an effective and consolidate treatment for steroid-refractory Graves’ ophthalmopathy (GO); however, long term effects are not well known. The aim of this study was to evaluate the long term efficacy and toxicity of orbital RT plus concomitant systemic steroids in a population of patients with moderate-to-severe GO or with eyesight threatening symptoms refractory to steroids. Forty patients with moderate-to-severe GO or with eyesight threatening symptoms not responsive/resistant to steroids were treated with orbital RT at the dose of 20 Gy in 10 fractions plus concomitant steroids. Clinical activity score (CAS) and symptoms status were evaluated to determine response to the treatment. We reported overall improvement of symptoms, in particular, a regression at 1-year of diplopia in 32.5% eye movement impairment in 42.5%, eyesight in 27.5% and a 2 point reduction in CAS. After a median time of 56 months 21.9% of the patients underwent orbital decompression for relapse of GO, 4.8% received surgical correction of strabismus, and 2.4% received eyelid lipectomy. Acute toxicity was mild; grade 1 - 2 keratitis occurred in 19.5% of the patients and grade 3 keratitis was observed in 2.4% of the patients. Cataract occurred in 7.4% of the patients after a median time of 24-month-follow-up. No secondary malignancies were reported. Our results reported the long-term efficacy and the good tolerance of orbital RT. The combination of RT plus steroids in this setting may avoid or delay performing the surgery in some cases.

The aim of this study was to compare the differences of the dosimetric parameters between three-dimensional conformal radiotherapy (3D-CRT) and simultaneous-integrated boost intensity-modulated radiotherapy (SIB-IMRT) techniques in the prone and supine positions for breast irradiation.
Ten patients underwent a computed tomography simulation in both the prone and supine positions. For each set-up position, the treatment plans were created with 3D-CRT and SIB-IMRT. The dosimetric parameters were obtained from dose-volume histograms.
High-dose regions in the whole breast were decreased in IMRT with a simultaneous integrated boost technique. The lung doses were significantly reduced for all patients, and the heart doses were lower in left-sided breast cancer patients in the prone position. The heart doses except mean dose were not significantly lower with SIB-IMRT in the prone position.
SIB-IMRT allowed a more conformal dose distribution regardless of position. The prone position is superior to the supine treatment regarding doses in the ipsilateral, contralateral lung, and heart. The contralateral breast doses were increased in the prone position. Prone IMRT can be chosen for simultaneous integrated boost treatment in women with pendulous breasts.

Breast cancer (BC) mortality rate has significantly decreased during the past decades by introducing adjuvant chemotherapy and/or radiotherapy (RT) in addition to surgery. However, as an emerging phenomenon, the corresponding therapeutic side effects caused non-malignant morbidity and mortality. Coronary artery disease (CAD) is the leading non-malignant cause of death in BC patients. It is established that chest RT has a role in atherosclerotic plaque formation in the coronary arteries. Newer techniques of RT like three-dimensional conformal radiotherapy (3D-CRT) use technical methods in which less radiation doses are given to the non-cancerous tissues. Non-invasive technique of coronary artery calcium score (CACS) can detect atherosclerotic plaques long before the plaques become symptomatic, helping to treat them in early stages, so improve BC patients’ outcome. The aim of this study is to assess and compare CACS in BC patients with a history of 3D-RT and non-BC women in the same age range with no history of RT.
CACS of fifty BC patients (age range: 34 - 70 years) with different time intervals from RT (range: 3-9 years) and CACS of fifty age-matched control group of non-BC women with no history of chest RT, using 64-slice ECG-gated CT scan were calculated and presented as the quantitative value of Agatston score (AS). The risk factors contributing to CAD (hypertension, hyperlipidemia, diabetes mellitus, smoking), and the Framingham’s 10-year risk score, as well as the age-matched CACS percentiles, were evaluated.
No correlation between AS and history of RT, RT-to-follow-up time interval, laterality of BC, Framingham’s 10-year risk score or traditional CAD risk factors were detected. Increase in CACS related to the senile atherosclerotic process was shown (P No difference between CACS was noted between BC patients with a history of 3D-CRT and the non-BC women without a history of RT. Although cardiac radiation dose reduction in 3D-CRT technique can justify the findings, as multiple studies have shown increase of CAD in BC patients with history of old RT techniques, but some studies show no difference in CACS between new and old RT techniques, other reason would be non-calcified atherosclerotic plaques after RT or myocardial microvascular disease due to reduced cardiac doses after 3D-CRT rather than calcified atherosclerotic plaques seen naturally by aging.

Aims: It was aimed to investigate postoperative conformal radiotherapy planning that provides the best target volume and the least dose for critical organs in cancers of stomach.
This study was conducted on the CT simulation images of thirty patients diagnosed with gastric cancer. Target volumes and the organs at risk were contoured. AP-PA reciprocal parallel field conventional plan and three- and four-field 3D conformal plans were created using linear accelerator. Target volumes and doses consumed by organs at risk were compared by dose-volume histograms.
While a sufficient dose could be applied to target volumes in all plans with conformal planning, average figures showed that 95% of porta hepatis area failed to take the prescribed dose (D95) in some plans by using AP-PA reciprocal parallel zone conventional plans. The most convenient protection for spinal cord, heart and kidneys was obtained by conformal four-field technique and the liver doses were increased in conformal four-field plans but did not exceed the tolerance dose. And also, in the conventional AP-PA reciprocal parallel field plans, tolerance dose of spinal cord (4500 cGy) was exceeded.
In this study, conformal four-field technique was superior considering target volume dose distributions, and especially spinal cord doses in all localizations and heart doses in cardia tumors. Kidney doses were also reduced in conformal four-field planning, but failed to reach statistical significance. There was a not exceeding tolerance limits dose increase in liver

Identify the optimal technique of radiotherapy for patients with high grade glioma. Our initial year of experience with RapidArc radiation therapy. Planning CT scans of 50 patients with grade IV glioma were reviewed and three plan sets by 3D Conformal Radiotherapy (3DCRT), Intensity Modulated Radiotherapy (IMRT) and Rapid Arc (RA) were generated and the plans were compared. Planning target Volume (PTV) coverage is comparable. However IMRT and RA give better sparing of critical structures. Treatment time and Monitor Units (MU) for Rapid Arc is much less compared to IMRT. If PTV is near to the Organs at Risk (OAR), then IMRT gives good result in comparison to 3DCRT plans. Rapid Arc is faster than IMRT and 3DCRT for same dose prescription to PTV and constraints of OAR.