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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Journal of Biomedical Physics and Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Imaging,Paraffin,Tomography, X-Ray Computed,Waxes
- چکیده:
- چکیده انگلیسی: Background: In general, radiotherapy treatment planning is performed using the virtual bolus. It is necessary to investigate physical bolus in comparison to virtual one.
Objectives: In the present study, first, radiological properties of superflab Gel bolus and Paraffin wax bolus was investigated in terms of their relative electron density. Then, dosimetric performance of both the bolus (i.e. Gel and Parafin wax) was compared with Virtual bolus.
Material and Methods: In This experimental study, the radiological property of Wax and Gel boluses was investigated using two methods. In one, the relative electron density of both the Gel and Wax boluses was calculated by measuring their linear attenuation coefficient where in another method relative electron density was calculated by recording their CT No directly from their CT scan. Later CT scan of solid water slab phantom (dimension 30x30x15 cm3), with physical boluses (i.e. Gel and Wax bolus) of appropriate thicknesses required to deliver a dose of 200 cGy at Dmax using 4 MV, 6 MV and 15 MV photon beams, was taken. These CT data sets were retrieved to TPS. A plan was done to deliver a dose of 200 cGy at Dmax using Single 4 MV, 6 MV and 15 MV photon beams. Dose at depths Dmax, 1 cm, 2 cm, 3 cm, 4 cm and 5 cm was recorded. Using this similar method, doses at depths viz Dmax, 1 cm, 2 cm, 3 cm, 4 cm and 5 cm was recorded for the Gel and Wax boluses. The differences in dose of gel and wax bolus from virtual bolus were recorded for comparison of their dosimetric performance.
Results: The measured (calculated) relative electron density of wax and Gel bolus was found to be 0.958 (0.926) and 0.923 (0.907), respectively. Variation in dosimetric performance of Gel and Wax with reference to Virtual bolus was studied. However, on average, Gel bolus was more consistent with virtual bolus.
Conclusion: To avoid any dose difference between, delivered (using physical bolus) and planned (using virtual bolus), the physical boluses should be investigated for their dosimetric performance in comparison to virtual bolus. The results obtained and methodology used in this study can be applied in routine radiotherapy practices.- انتشار مقاله: 17-02-1398
- نویسندگان: T R Verma,N K Painuly,M Tyagi,D Johny,R Gupta,M L B Bhatt
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Biomedical Physics and Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Radiography,Organs at Risk,Brachytherapy
- چکیده:
- چکیده انگلیسی: Background: Brachytherapy treatment planning in cervix carcinoma patients using two dimensional (2D) orthogonal images provides only point dose estimates while CT-based planning provides volumetric dose assessment helping in understanding the correlation between morbidity and the dose to organs at risk (OARs) and treatment volume.
Objective: Aim of present study is to compare International Commission on Radiation Units and Measurements Report 38 (ICRU 38) reference point doses to OARs with volumetric doses using 2D images and CT images in patients with cervical cancer.
Material and Methods: In this prospective study, 20 patients with cervical cancer stages (IIB-IIIB) were planned for a brachytherapy dose of 7Gy per fraction for three fractions using 2D image-based treatment plan and CT-based plan. ICRU 38 points for bladder and rectum were identified on both 2D image-based plan and CT-based plan and doses (DICRU) at these points were compared to the minimum dose to 2cc volume (D2cc) of bladder and rectum receiving the highest dose.
Results: D2cc bladder dose was 1.60 (±0.67) times more than DICRUb bladder dose whereas D2cc rectum dose was 1.13±0.40 times DICRUr. Significant difference was found between DICRUb and D2cc dose for bladder (p=.0.016) while no significant difference was seen between DICRUr and D2cc dose for rectum (p=0.964).
Conclusion: The study suggests that ICRU 38 point doses are not the true representation of maximum doses to OARs. CT-based treatment planning is more a reliable tool for OAR dose assessment than the conventional 2D radiograph-based plan.- انتشار مقاله: 28-08-1396
- نویسندگان: Sh Srivastava,N K Painuly,S P Mishra,K Srivastava,N Singh,S Singh,M L B Bhatt
- مشاهده
- جایگاه : پژوهشی
- مجله: Journal of Biomedical Physics and Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: algorithms,Monte Carlo,Superposition,Lung IMRT,Pencil Beam,Dose to OARs
- چکیده:
- چکیده انگلیسی: Background: Inclusion of inhomogeneity corrections in intensity modulated small fields always makes conformal irradiation of lung tumor very complicated in accurate dose delivery.Objective: In the present study, the performance of five algorithms via Monte Carlo, Pencil Beam, Convolution, Fast Superposition and Superposition were evaluated in lung cancer Intensity Modulated Radiotherapy planning.Materials and Methods: Treatment plans for ten lung cancer patients previously planned on Monte Carlo algorithm were re-planned using same treatment planning indices (gantry angel, rank, power etc.) in other four algorithms.Results: The values of radiotherapy planning parameters such as Mean dose, volume of 95% isodose line, Conformity Index, Homogeneity Index for target, Maximum dose, Mean dose; %Volume receiving 20Gy or more by contralateral lung; % volume receiving 30 Gy or more; % volume receiving 25 Gy or more, Mean dose received by heart; %volume receiving 35Gy or more; %volume receiving 50Gy or more, Mean dose to Easophagous; % Volume receiving 45Gy or more, Maximum dose received by Spinal cord and Total monitor unit, Volume of 50 % isodose lines were recorded for all ten patients. Performance of different algorithms was also evaluated statistically.Conclusion: MC and PB algorithms found better as for tumor coverage, dose distribution homogeneity in Planning Target Volume and minimal dose to organ at risks are concerned. Superposition algorithms found to be better than convolution and fast superposition. In the case of tumors located centrally, it is recommended to use Monte Carlo algorithms for the optimal use of radiotherapy.Â
- انتشار مقاله: 29-02-1394
- نویسندگان: T R Verma,N K Painuly,S P Mishra,M Shajahan,N Singh,M L B Bhatt,N Jamal,M C Pant
- مشاهده
- جایگاه : پژوهشی
- مجله: Asian Pacific Journal of Cancer Prevention
- نوع مقاله: Journal Article
- کلمات کلیدی: gene polymorphism,Oral pre cancer and cancer,CYP1A1,PCR-RFLP
- چکیده:
- چکیده انگلیسی: Background: The aim of this study was to evaluate any association between CYP1A1 (T6235C and C4887A,
A4889G) gene polymorphisms and the risk of oral pre-cancer and cancer. Methods: In the present study, 250 patients
with oral pre-cancer and/or cancer and 250 healthy controls were genotyped for CYP1A1 T6235C, C4887Aand A4889G
polymorphisms by the PCR-RFLP method. Results: None of the CYP1A1 polymorphisms were associated with the risk of
either oral cancer or pre cancer. Nor were any links with clinical parameters of oral cancer found. However, among the
consumers of areca nut/pan masala the TC, CA and AG genotypes respectively for the CYP1A1 T6235C,C4887Aand
A4889G polymorphisms were significantly more frequent in controls compared to cases ( p values for cases vs. controls
of 0.0032, 0.0019 and 0.0009, respectively). Similarly, compared to the haplotype TCA, TAG constituted by CYP1A1
T6235C and C4887A and A4889G was more common in controls (6.88%) than in cases (4.07%). Conclusion: Our
results suggest that genotypes regarding CYP1A1 polymorphisms may modulate the risk of oral cancer and pre-cancer
among the areca nut/pan masala consumers. The haplotype may also exert an influence in our north Indian population.- انتشار مقاله: 28-04-1396
- نویسندگان: Kumud Nigam,Somali Sanyal,Shalini Gupta,Om Prakash Gupta,Abbas Ali Mahdi,M L B Bhatt
- مشاهده