Publications by authors named "Prabhakar Ramachandran"

34 Publications

A 3D printed phantom to assess MRI geometric distortion.

Biomed Phys Eng Express 2021 Mar 3. Epub 2021 Mar 3.

Queensland University of Technology, 199 Ipswich Road, Brisbane, 4102, AUSTRALIA.

Magnetic Resonance has become a standard imaging modality for target volume delineation and treatment planning in radiation oncology. Geometric distortions, however, have the potential to detrimentally affect both tumour definition and the dose delivered to the target volume. We report the design, fabrication and imaging of a 3D printed unibody MR distortion phantom along with quantitative image analysis.

Methods: The internal cavity of the phantom is an orthogonal three-dimensional planar lattice, composed of 3mm diameter rods spaced equidistantly at a 20mm centre-centre offset repeating along the X, Y and Z axes. The phantom featured an overall length of 308.5 mm, a width of 246 mm and a height of 264 mm with lines on the external surface for phantom positioning matched to external lasers. The MR phantom was 3D printed in Nylon-12 using an advancement on traditional selective laser sintering (SLS) (HP Jet Fusion 3D - 4200 machine). The phantom was scanned on a Toshiba Aquilion CT scanner to check the integrity of the 3D print and to correct for any resultant issues. The phantom was then filled with NiSO4 solution and scanned on a 3T PET-MR Siemens scanner for selected T1 and T2 sequences, from which distortion vectors were generated and analysed using in-house software written in Python.

Results: All deviations were less than 1 mm, with an average displacement of 0.228 mm. The majority of the deviations are smaller than the 0.692 mm pixel size for this dataset.

Conclusion: A cost-effective, 3D printed MRI-phantom was successfully printed and tested for assessing geometric distortion on MRI scanners. The custom phantom with markings for phantom alignment may be considered for radiotherapy departments looking to add MR scanners for simulation and image guidance.
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http://dx.doi.org/10.1088/2057-1976/abeb7eDOI Listing
March 2021

Dosimetric comparative study of 3DCRT, IMRT, VMAT, Ecomp, and Hybrid techniques for breast radiation therapy.

Radiat Oncol J 2020 Dec 15;38(4):270-281. Epub 2020 Dec 15.

School of Health and Biomedical Sciences, RMIT University, Melbourne, Australia.

Purpose: To assess and compare the dosimetric parameters obtained between three-dimensional conformal radiotherapy (3DCRT), three-dimensional field-in-field (3DFIF), 5-field intensity-modulated radiotherapy (IMRT MF5), tangential IMRT (tIMRT), tangential volumetric modulated arc therapy (tVMAT), electronic tissue compensation (Ecomp), and Hybrid treatment plans.

Materials And Methods: Thirty planning computed tomography datasets obtained from patients previously treated with whole breast radiation therapy (WBRT) were utilized in this study. Treatment plans were created for 3DCRT, 3DFIF, IMRT MF5, tIMRT, tVMAT, Ecomp, and Hybrid techniques using Eclipse Treatment Planning System (version 13.6) with a prescribed dose of 42.5 Gy in 16 fractions.

Results: Techniques with tangential beams produced statistically significantly better organs-at-risk (OARs) dosimetry (p < 0.001). Planning target volume Homogeneity Index (HI) was found to be significantly different among all techniques (p < 0.001), with Ecomp resulting in better HI (1.061 ± 0.029). Ecomp was also observed to require relatively shorter planning time (p < 0.001).

Conclusions: Techniques using tangential fields arrangements produced improved OARs dosimetry. Of all the treatment planning techniques employed in this study, Ecomp was found to be relatively easy to plan and produce acceptable dosimetry for WBRT in a short time.
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http://dx.doi.org/10.3857/roj.2020.00619DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7785843PMC
December 2020

Development of a multicentre automated model to reduce planning variability in radiotherapy of prostate cancer.

Phys Imaging Radiat Oncol 2019 Jul 8;11:34-40. Epub 2019 Aug 8.

Dept Health & Human Services, Victoria, Australia.

Background And Purpose: Inter-institutional studies highlighted correlation between consistent radiotherapy quality and improved overall patient survival. In treatment planning automation has the potential to address differences due to user-experience and training, promoting standardisation. The aim of this study was to evaluate implementation and clinical effect of a multicentre collaboratively-developed automated planning model for Intensity-Modulated Radiation Therapy/Volumetric-Modulated Arc Therapy of prostate. The model was built using a variety of public institutions' clinical plans, incorporating different contouring and dose protocols, aiming at minimising their variation.

Methods And Materials: A model using 110 clinically approved and treated prostate plans provided by different radiotherapy centres was built with RapidPlan (RP), for use on intact and post-prostatectomy prostate cases. The model was validated, distributed and introduced into clinical practice in all institutions. To investigate its impact a total of 126 patients, originally manually inverse planned (OP), were replanned using RP without additional planner manual intervention. Target and organ-at-risk (OAR) metrics were statistically compared between original and automated plans.

Results: For all centres combined and individually, RP provided plans comparable or superior to OP for all dose metrics. Statistically significant reductions with RP were found in bladder (V40Gy) and rectal (V50Gy) low doses (within 2.3% and 3.4% for combined and 4% and 10% individually). No clinically significant changes were seen for the PTV, independently of seminal vesicle inclusion.

Conclusion: This project showed it is feasible to develop, share and implement RP models created with plans from different institutions treated with a variety of techniques and dose protocols, with the potential of improving treatment planning results and/or efficiency despite the original variability.
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http://dx.doi.org/10.1016/j.phro.2019.07.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7807596PMC
July 2019

On the use of AAA and AcurosXB algorithms for three different stereotactic ablative body radiotherapy (SABR) techniques: Volumetric modulated arc therapy (VMAT), intensity modulated radiation therapy (IMRT) and 3D conformal radiotherapy (3D-CRT).

Rep Pract Oncol Radiother 2019 Jul-Aug;24(4):399-408. Epub 2019 Mar 23.

School of Health & Biomedical Sciences, RMIT University, Victoria, Australia.

Aim: The purpose of this study was to investigate the dosimetric characteristics of three stereotactic ablative body radiotherapy (SABR) techniques using the anisotropic analytical algorithm (AAA) and Acuros XB algorithm. The SABR techniques include coplanar volumetric modulated arc therapy (C-VMAT), non-coplanar intensity modulated radiation therapy (NC-IMRT) and non-coplanar three-dimensional conformal radiotherapy (NC-3D CRT).

Background: SABR is a special type of radiotherapy where a high dose of radiation is delivered over a short time. The treatment outcome and accuracy of the dose delivered to cancer patients highly depend on the dose calculation algorithm and treatment technique.

Materials And Methods: Twelve lung cancer patients underwent 4D CT scanning, and three different treatment plans were generated: C-VMAT, NC-IMRT, NC-3D CRT. Dose calculation was performed using the AAA and Acuros XB algorithm. The dosimetric indices, such as conformity index (CI), homogeneity index, dose fall-off index, doses received by organs at risk and planning target volume, were used to compare the plans. The accuracy of AAA and Acuros XB (AXB) algorithms for the lung was validated against measured dose on a CIRS thorax phantom.

Results: The CIs for C-VMAT, NC-IMRT and NC-3D CRT were 1.21, 1.28 and 1.38 for the AAA, respectively, and 1.17, 1.26 and 1.36 for the Acuros XB algorithm, respectively. The overall dose computed by AcurosXB algorithm was close to the measured dose when compared to the AAA algorithm. The overall dose computed by the AcurosXB algorithm was close to the measured dose when compared to the AAA algorithm.

Conclusion: This study showed that the treatment planning results obtained using the Acuros XB algorithm was better than those using the AAA algorithm in SABR lung radiotherapy.
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http://dx.doi.org/10.1016/j.rpor.2019.02.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6624189PMC
March 2019

Determination of dose enhancement caused by AuNPs with Xoft Axxent Electronic (eBx™) and conventional brachytherapy: in vitro study.

Int J Nanomedicine 2018 25;13:5733-5741. Epub 2018 Sep 25.

Discipline of Medical Radiation, School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia,

Purpose: The purpose of this study was to determine dose enhancement (DE) and the possible clinical benefits associated with the inclusion of gold nanoparticles (AuNPs) in cancer cells irradiated by either an Ir brachytherapy source or a Xoft Axxent Electronic (eBx™) Brachytherapy.

Patients And Methods: Brachytherapy DE caused by AuNPs is investigated using two methods, namely Ir and eBx™ Brachytherapy. The second method, which was recently introduced clinically, operates at ~50 kV, which is also the optimal beam energy for DE. In this in vitro study, two cancer cell lines, lung (A549) and prostate (DU145), were used. Cells were incubated with 1 mM (2% w/w) concentration of AuNPs of ~15 nm in size. The control groups were exposed to a range of doses from 0 (control) to 6 Gy, with eBx™ and Ir sources separately. A clonogenic assay was conducted to determine cell survival curves.

Results: High dose enhancement factor (DEF) values were achieved in treated groups with low concentration of AuNPs with the 50 kV energy associated with the eBx™. The DE levels in eBx™ for Du145 and A549 cells were found to be 2.90 and 2.06, respectively. The results showed DEFs measured for the same cell lines using Ir brachytherapy to be 1.67 and 1.54 for Du145 and A549 cancer cells, respectively. This clearly indicates that much higher DE values are obtained in the case of eBx™ X-ray brachytherapy compared to Ir gamma brachytherapy.

Conclusion: The higher DE values obtained with eBx™ compared to Ir brachytherapy can be attributed to the lower average energy of the former and being closer to the optimal energy for DE. This could potentially be utilized by medical practitioners and clinicians to achieve the same tumor control with a significantly lower dose from the eBx™ compared to the Ir brachytherapy treatment, thus bringing huge benefits to the brachytherapy-treated patients.
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http://dx.doi.org/10.2147/IJN.S174624DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6165788PMC
November 2018

Evaluation and Performance of ArcCheck and Film using Gamma Criteria in Pre-treatment Quality Assurance of Stereotactic Ablative Radiotherapy.

J Med Phys 2017 Oct-Dec;42(4):251-257

Medical Radiation Discipline, School of Health and Biomedical Science, RMIT University, Bundoora, Victoria, Australia.

Aim: The aim of this study is to assess the use of ArcCHECK (AC) as an alternative method to replace film dosimetry for pre-treatment quality assurance (QA) of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) stereotactic ablative radiotherapy (SABR) treatment plans.

Materials And Methods: Twenty-five patients with a varied diagnosis of lung, spine, sacrum, sternum, ribs, scapula, and femur undergoing SABR were selected for this study. Pre-treatment QA was performed for all the patients using ionization chamber and film dosimetry. Measurements were also carried out on an AC phantom. The planned and measured doses from the AC device and EBT3 films were compared using four different gamma criteria: 2%/2 mm, 3%/2 mm, 3%/1 mm, and 3%/3 mm.

Results: The mean gamma passing rates at 3%/3 mm for all non-spine SABR cases were 98.79 ± 0.96 and 99.27 ± 1.03 with AC and films, respectively. The mean passing rates at 3%/2 mm for AC and films were 98.76 ± 0.42 and 99.43 ± 0.27 respectively for spine VMAT SABR, and 87.15 ± 2.45 and 99.79 ± 0.14 respectively for spine IMRT SABR. In the case of spine tumors, the gamma criterion was tightened due to the proximity of spinal cord to the planning target volume. Our results show that AC provides good results for all VMAT SABR plans.

Conclusion: The AC results at 3%/3 mm were in good agreement with film dosimetry for most cases. We observed a significant reduction in QA time on using AC for SABR QA. This study showed that AC results are comparable to film dosimetry for all studied sites except for spine IMRT SABR.
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http://dx.doi.org/10.4103/jmp.JMP_132_16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5744454PMC
January 2018

Surface dose measurements in and out of field: Implications for breast radiotherapy with megavoltage photon beams.

Z Med Phys 2017 Dec 7;27(4):318-323. Epub 2017 Jun 7.

Peter MacCallum Cancer Centre, Melbourne, Australia; RMIT University, Melbourne, Australia.

This study examines the difference in surface dose between flat and flattening filter free (FFF) photon beams in the context of breast radiotherapy. The surface dose was measured for 6MV, 6MV FFF, 10MV, 10MV FFF and 18MV photon beams using a thin window ionisation chamber for various field sizes. Profiles were acquired to ascertain the change in surface dose off-axis. Out-of-field measurements were included in a clinically representative half beam block tangential breast field. In the field centres of FFF beams the surface dose was found to be increased for small fields and decreased for large fields compared to flat beams. For FFF beams, surface dose was found to decrease off-axis and resulted in lower surface dose out-of-field compared to flat beams.
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http://dx.doi.org/10.1016/j.zemedi.2017.05.002DOI Listing
December 2017

New era of electronic brachytherapy.

World J Radiol 2017 Apr;9(4):148-154

Prabhakar Ramachandran, Department of Physical Sciences, Peter MacCallum Cancer Centre, Melbourne, VIC 3165, Australia.

Traditional brachytherapy refers to the placement of radioactive sources on or inside the cancer tissues. Based on the type of sources, brachytherapy can be classified as radionuclide and electronic brachytherapy. Electronic brachytherapy uses miniaturized X-ray sources instead of radionuclides to deliver high doses of radiation. The advantages of electronic brachytherapy include low dose to organs at risk, reduced dose to treating staff, no leakage radiation in off state, less shielding, and no radioactive waste. Most of these systems operate between 50 and 100 kVp and are widely used in the treatment of skin cancer. Intrabeam, Xoft and Papillon systems are also used in the treatment of intra-operative radiotherapy to breast in addition to other treatment sites. The rapid fall-off in the dose due to its low energy is a highly desirable property in brachytherapy and results in a reduced dose to the surrounding normal tissues compared to the Ir-192 source. The Xoft Axxent brachytherapy system uses a 2.25 mm miniaturized X-ray tube and the source almost mimics the high dose rate Ir-192 source in terms of dose rate and it is the only electronic brachytherapy system specifically used in the treatment of cervical cancers. One of the limiting factors that impede the use of electronic brachytherapy for interstitial application is the source dimension. However, it is highly anticipated that the design of miniaturized X-ray tube closer to the dimension of an Ir-192 wire is not too far away, and the new era of electronic brachytherapy has just begun.
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http://dx.doi.org/10.4329/wjr.v9.i4.148DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5415885PMC
April 2017

Geographical miss of the prostate during image-guided radiotherapy with a 6-mm posterior expansion margin.

J Med Radiat Sci 2017 Jun 8;64(2):97-105. Epub 2016 Nov 8.

Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Australia.

Introduction: Our department commonly uses a planning target volume (PTV) expansion of 6 mm posterior and 1 cm in all other directions when treating prostate cancer patients with image-guided radiotherapy (IGRT). This study aimed to test the adequacy of this PTV expansion by assessing geographical miss of the prostate on post-treatment cone-beam CT (CBCT) and identify those at risk of geographical miss.

Methods: Twenty-two prostate cancer patients receiving IGRT with implanted fiducial markers underwent daily pre-treatment orthogonal kV imaging followed by a post-treatment CBCT for a total of 432 fractions. The prostate was outlined on all CBCTs. For each imaging set, the volume of geographic miss was measured by subtracting the PTV from the planning CT and prostate volume on the post-treatment CBCT.

Results: The prostate volume moved outside the PTV by >0.01 cc in 9% of fractions (39/432). This occurred in 13 (59%) of 22 patients. Large prostates >40 cc and >50 cc had significantly more geographical miss events (both P < 0.001). Changes in rectal filling appear to be responsible for prostate motion/deformation in 82% (32/39) of fractions.

Conclusions: Our analysis suggests that, despite IGRT, prostate PTV margins are not adequate in some patients, particularly those with large prostates. PTV margins may be reduced in some other patients. Prostate rotation and deformation play an important role in setting margins and may not always be represented accurately by fiducial marker displacements. Individualised and adaptive margins for prostate cancer patients should be a priority for future research.
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http://dx.doi.org/10.1002/jmrs.186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5454331PMC
June 2017

Immediate and Delayed Effects of Diode Laser on Debonding of Ceramic Brackets: An in vitro Study.

J Contemp Dent Pract 2016 Apr 1;17(4):275-81. Epub 2016 Apr 1.

Department of Orthodontics, Thai Moogambigai Dental College and Hospital, Chennai, Tamil Nadu, India.

Aim: The aim of the study is to evaluate the immediate and delayed effects of diode laser on debonding of ceramic brackets.

Materials And Methods: A total of 60 human extracted premolar teeth were randomly assigned to three different treatment groups. All teeth were bonded with adhesive precoated (APC) ceramic brackets (3M Unitek). A total of 20 teeth were debonded without lasing (group 1), 20 immediately after lasing (group 2), and 20 1 hour after lasing (group 3). For the lasing groups (groups 2 and 3), access cavity was prepared on the occlusal surface to a 2 mm diameter. A transbond plus self-etching primer (3M Unitek, Monrovia, CA, USA) and APC PLUS clarity advanced brackets (3M, Unitek, Monrovia, CA, USA) were used. The shear bond strength (SBS) and adhesive remnant index (ARI) were measured. The internal pulpal wall temperature was noted for the laser groups.

Results: The mean SBS was 15.4, 11.57, and 11.79 MPa for groups 1 to 3 respectively. Post hoc test showed significant difference (p < 0.001) between the control group and the lased groups. For groups 2 and 3, the rise in temperature was at an average of 1.4 and 1.3°C respectively.

Conclusion: The SBS of APC brackets decreased by 33.3% on application of diode laser without increasing the internal pulp chamber wall temperature significantly. Shear bond strength remains more or less the same whether debonding is done immediately after lasing or 1 hour after lasing. Diode lasers increased the ARI scores and thus decreased the risk of enamel fracture.
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http://dx.doi.org/10.5005/jp-journals-10024-1841DOI Listing
April 2016

Rectal complication probability from composite volumes derived from daily cone beam computed tomography in prostate cancer radiotherapy.

J Cancer Res Ther 2016 Jan-Mar;12(1):374-8

Department of Physical Sciences, Peter MacCallum Cancer Centre, St. Andrew Place, East Melboure, Vic 3002; Bendigo Radiotherapy Centre, Peter MacCallum Cancer Centre, Stewart Street, Vic 3550; School of Med Sciences, RMIT University, Bundoora Campus, Bundoora, Vic 3083, Australia.

Aim: The aim of this study is to investigate the rectal complication probabilities for various rectum volumes with intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiotherapy (3D-CRT) in patients undergoing prostate cancer radiotherapy.

Materials And Methods: Thirteen patients undergoing prostate cancer radiotherapy were consecutively selected for this study. All patients were treated with IMRT to a dose of 78 Gy in 39 fractions. Three different rectum volumes: (i) planned rectum (plan-rectum) (ii) Boolean sum of rectum volume based on the cone-beam computed tomography (CBCT) for first five fractions (planning organ at risk volumes [PRV]-CBCT-5), (iii) Boolean sum of rectum volume from all the CBCTs (PRV-CBCT-All) in addition to an average rectal complication (PRV-CBCT-AV) were used for computing the probabilities of rectal complications. To assess the rectal complications with 3D-CRT, a five-field plan was generated for comparison with IMRT. The Lyman-Kutcher-Burman (LKB) normal tissue complication probability (NTCP) model was used to assess the rectal complications for all of the defined rectal volumes.

Results: The NTCPs for rectum as assessed from plan-rectum, PRV-CBCT-5, PRV-CBCT-All, and PRV-CBCT-AV with IMRT were 9.71% ±4.69%, 16.34% ±9.51%, 19.39% ±9.71%, and 12.81% ±7.22%, respectively. Similarly, with 3D-CRT, the NTCPs were 17.41% ±10.44%, 19.61% ±11.08%, 21.03% ±11.06%, and 17.72% ±10.29%, respectively.

Conclusion: Our results showed that the rectal complications are reduced significantly with IMRT as compared to 3D-CRT. As such, the analyses of NTCP with various defined composite rectum volumes indicate that IMRT requires image-guided adaptive radiotherapy as opposed to 3D-CRT.
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http://dx.doi.org/10.4103/0973-1482.174529DOI Listing
December 2016

RADBIOMOD: A simple program for utilising biological modelling in radiotherapy plan evaluation.

Phys Med 2016 Jan 6;32(1):248-54. Epub 2015 Nov 6.

Radiation Oncology Centre, Austin Health, Heidelberg, Victoria, Australia; University of Melbourne, Victoria, Australia; Department of Clinical Oncology, Royal Marsden Hospital Trust & Institute of Cancer Research, London, UK.

Purpose: Radiotherapy plan evaluation is currently performed by assessing physical parameters, which has many limitations. Biological modelling can potentially allow plan evaluation that is more reflective of clinical outcomes, however further research is required into this field before it can be used clinically.

Methods: A simple program, RADBIOMOD, has been developed using Visual Basic for Applications (VBA) for Microsoft Excel that incorporates multiple different biological models for radiotherapy plan evaluation, including modified Poisson tumour control probability (TCP), modified Zaider-Minerbo TCP, Lyman-Kutcher-Burman normal tissue complication probability (NTCP), equivalent uniform dose (EUD), EUD-based TCP, EUD-based NTCP, and uncomplicated tumour control probability (UTCP). RADBIOMOD was compared to existing biological modelling calculators for 15 sample cases.

Results: Comparing RADBIOMOD to the existing biological modelling calculators, all models tested had mean absolute errors and root mean square errors less than 1%.

Conclusions: RADBIOMOD produces results that are non-significantly different from existing biological modelling calculators for the models tested. It is hoped that this freely available, user-friendly program will aid future research into biological modelling.
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http://dx.doi.org/10.1016/j.ejmp.2015.10.091DOI Listing
January 2016

Automatic tracking of gold seed markers from CBCT image projections in lung and prostate radiotherapy.

Phys Med 2015 Mar 23;31(2):185-91. Epub 2015 Jan 23.

Peter MacCallum Cancer Centre, Melbourne, Victoria 3002, Australia.

Purpose: To construct a method and software to track gold seed implants in prostate and lung patients undergoing radiotherapy using CBCT image projections.

Methods: A mathematical model was developed in the MatLab (Mathworks, Natick, USA) environment which uses a combination of discreet cosine transforms and filtering to enhance several edge detection methods for identifying and tracking gold seed fiducial markers in images obtained from Varian (Varian Medical Systems, Palo Alto, USA) and Elekta (Kungstensgatan, Sweden) CBCT projections.

Results: Organ motion was captured for 16 prostate patients and 1 lung patient.

Conclusion: Image enhancement and edge detection is capable of automatically tracking markers for up to 98% (Varian) and 79% (Elekta) of CBCT projections for prostate and lung markers however inclusion of excessive bony anatomy (LT and RT LAT) inhibit the ability of the model to accurate determine marker location.
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http://dx.doi.org/10.1016/j.ejmp.2015.01.002DOI Listing
March 2015

Extrusion of impacted mandibular second molar using removable appliance.

J Pharm Bioallied Sci 2014 Jul;6(Suppl 1):S212-4

Department of Orthodontics, Thai Moogambigai Dental College and Hospital, Chennai, Tamil Nadu, India.

The purpose of this article is to review the principles of case management of impacted mandibular molars and to illustrate their potential to respond well to treatment. Although the scope of treatment may be influenced by the patient's age, past dental history, severity of impaction, dentoalveolar development, and root form, the case reports demonstrate the inherent potential for good treatment outcome even in the most unfavorable circumstances.
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http://dx.doi.org/10.4103/0975-7406.137475DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4157274PMC
July 2014

Volumetric modulated arc therapy for prostate cancer patients with hip prosthesis.

Rep Pract Oncol Radiother 2013 28;18(4):209-13. Epub 2013 Apr 28.

Peter MacCallum Cancer Centre, Victoria, Australia.

Aim: To study the use of RapidArc techniques in the treatment of prostate cancer patients with hip prosthesis.

Background: An important aspect of treatment planning is to achieve dose homogeneity inside the planning target volume (PTV). Especially for those patients presenting with hip prosthesis, it becomes a challenging task to achieve dose uniformity inside the PTV.

Materials And Methods: Five prostate patients presenting with hip prosthesis who had undergone radical radiotherapy were selected for this study. Depending on the composition of prosthesis, a predefined set of Hounsfield values were assigned to each study set. RapidArc plans were generated on an Eclipse treatment planning system. Two arcs that include clockwise and counter-clockwise arcs were used in all these cases. To avoid beams passing through the prosthesis, a simple structure was defined around it with 1 cm margin and a strict dose constraint applied to the block during VMAT optimization.

Results: The mean D2/D98 ratio of PTV for all the patients was 1.06 ± 0.01. The mean percentage rectum volume receiving 50 Gy, 60 Gy, 70 Gy and 75 Gy for all the patients were 33.1 ± 5.9, 21.7 ± 5.5, 13.8 ± 4.4 and 9.5 ± 3.0, respectively.

Conclusions: This study shows that using a double arc RapidArc technique is a simple and effective treatment method of treating prostate cancer in patients presenting with a hip prosthesis. The definition of a beam avoidance structure encompassing the prosthesis and applying strict dose constraints to it reduces the beam contribution to the prosthesis.
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http://dx.doi.org/10.1016/j.rpor.2013.03.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3863326PMC
January 2014

A study on planning organ at risk volume for the rectum using cone beam computed tomography in the treatment of prostate cancer.

Med Dosim 2014 8;39(1):38-43. Epub 2014 Jan 8.

Radiation Therapy Services, Peter MacCallum Cancer Centre, Melbourne, Australia.

In this study, we analyzed planning organ at risk volume (PRV) for the rectum using a series of cone beam computed tomographies (CBCTs) acquired during the treatment of prostate cancer and evaluated the dosimetric effect of different PRV definitions. Overall, 21 patients with prostate cancer were treated radically with 78Gy in 39 fractions had in total 418 CBCTs, each acquired at the end of the first 5 fractions and then every alternate fraction. The PRV was generated from the Boolean sum volume of the rectum obtained from first 5 fractions (PRV-CBCT-5) and from all CBCTs (PRV-CBCT-All). The PRV margin was compared at the superior, middle, and inferior slices of the contoured rectum to compare PRV-CBCT-5 and PRV-CBCT-All. We also compared the dose received by the planned rectum (Rectum-computed tomography [CT]), PRV-CBCT-5, PRV-CBCT-All, and average rectum (CBCT-AV-dose-volume histogram [DVH]) at critical dose levels. The average measured rectal volume for all 21 patients for Rectum-CT, PRV-CBCT-5, and PRV-CBCT-All was 44.3 ± 15.0, 92.8 ± 40.40, and 121.5 ± 36.7cm(3), respectively. For PRV-CBCT-All, the mean ± standard deviation displacement in the anterior, posterior, right, and left lateral directions in centimeters was 2.1 ± 1.1, 0.9 ± 0.5, 0.9 ± 0.8, and 1.1 ± 0.7 for the superior rectum; 0.8 ± 0.5, 1.1 ± 0.5, 1.0 ± 0.5, and 1.0 ± 0.5 for the middle rectum; and 0.3 ± 0.3; 0.9 ± 0.5; 0.4 ± 0.2, and 0.5 ± 0.3 for the inferior rectum, respectively. The first 5 CBCTs did not predict the PRV for individual patients. Our study shows that the PRV margin is different for superior, middle, and the inferior parts of the rectum, it is wider superiorly and narrower inferiorly. A uniform PRV margin does not represent the actual rectal variations during treatment for all treatment fractions. The large variation in interpatient rectal size implies a potential role for adaptive radiotherapy for prostate cancer.
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http://dx.doi.org/10.1016/j.meddos.2013.09.003DOI Listing
September 2014

Real-time dosimetry in external beam radiation therapy.

World J Radiol 2013 Oct;5(10):352-5

Ramachandran Prabhakar, Department of Physical Sciences, Peter MacCallum Cancer Centre, Victoria 8006, Australia.

With growing complexity in radiotherapy treatment delivery, it has become mandatory to check each and every treatment plan before implementing clinically. This process is currently administered by an independent secondary check of all treatment parameters and as a pre-treatment quality assurance (QA) check for intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy treatment plans. Although pre-treatment IMRT QA is aimed to ensure the correct dose is delivered to the patient, it does not necessarily predict the clinically relevant patient dose errors. During radiotherapy, treatment uncertainties can affect tumor control and may increase complications to surrounding normal tissues. To combat this, image guided radiotherapy is employed to help ensure the plan conditions are mimicked on the treatment machine. However, it does not provide information on actual delivered dose to the tumor volume. Knowledge of actual dose delivered during treatment aid in confirming the prescribed dose and also to replan/reassess the treatment in situations where the planned dose is not delivered as expected by the treating physician. Major accidents in radiotherapy would have been averted if real time dosimetry is incorporated as part of the routine radiotherapy procedure. Of late real-time dosimetry is becoming popular with complex treatments in radiotherapy. Real-time dosimetry can be either in the form of point doses or planar doses or projected on to a 3D image dataset to obtain volumetric dose. They either provide entrance dose or exit dose or dose inside the natural cavities of a patient. In external beam radiotherapy, there are four different established platforms whereby the delivered dose information can be obtained: (1) Collimator; (2) Patient; (3) Couch; and (4) Electronic Portal Imaging Device. Current real-time dosimetric techniques available in radiotherapy have their own advantages and disadvantages and a combination of one or more of these methods provide vital information about the actual dose delivered to radiotherapy patients.
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http://dx.doi.org/10.4329/wjr.v5.i10.352DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812446PMC
October 2013

A study of segment weight optimization with the CMS XiO step-and-shoot IMRT technique for prostate cancer.

J Appl Clin Med Phys 2012 Jan 5;13(1):3622. Epub 2012 Jan 5.

Physical Sciences, Peter MacCallum Cancer Centre, Victoria, Australia.

The aim of this study was to compare IMRT optimization in the CMS XiO radiotherapy treatment planning system, with and without segment weight optimization. Twenty-one prostate cancer patients were selected for this study. All patients were initially planned with step-and-shoot IMRT (S-IMRT). A new plan was then created for each patient by applying the segment weight optimization tool (SWO-IMRT). Analysis was performed on the (SWO-IMRT) and (S-IMRT) plans by comparing the total number of segments, monitor units, rectal and bladder dose. The study showed a statistically significant reduction in the total number of segments (mean: 25.3%; range: 16.8%-31.1%) with SWO-IMRT as compared to S-IMRT (p < 0.0001). Similarly, a mean reduction of 3.8% (range: 0.4%-7.7%) in the total MU was observed with SWO-IMRT (p < 0.0001). The study showed an average rectal dose decrease of 13.7% (range: 7.9%-21.4%) with SWO-IMRT (p < 0.0001). We also observed a statistically significant reduction of 26.7% (range: 16.0%-41.4%; p < 0.0001) in the mean dose to the posterior one-third rectum and an overall reduction in mean bladder dose of 2.2% (range: 0.1%-6.1%) for SWO-IMRT (p < 0.0001). This study shows that the segment weight optimization method significantly reduces the total number of segments and the dose to the rectum for IMRT prostate cancer. It also resulted in fewer monitor units for most of the prostate cases observed in this study.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5716144PMC
http://dx.doi.org/10.1120/jacmp.v13i1.3622DOI Listing
January 2012

A simple plan evaluation index based on the dose to critical structures in radiotherapy.

J Med Phys 2011 Oct;36(4):192-7

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

The dose to critical structures plays a very important role in treatment plan evaluation and forms a major challenging parameter in radiotherapy treatment planning. In this study, a simple index, Plan Normal tissue complication Index (PNI) has been proposed for treatment plan evaluation based on the dose to surrounding critical structures. To demonstrate the proposed index, four different critical treatment sites that include the prostate, upper abdominal cancer, lung, and head and neck were selected for this study. A software progam (PNIcalc) has been developed to compute the PNI from the exported dose-volume histogram data and from the tissue tolerance data published by Emami et al. and Kehwar et al. The software also shows the parameters that exceed the threshold limits of dose-volume parameters presented in the QUANTEC recommendations (2010). In all the studied cases, PNI gave an overall picture of the dose received by the critical structures and also indicate the fractional volume exceeding the tolerance limit. The proposed index, PNI gives a quick comparison and selection of treatment plans that result in reduced dose to the critical structures. It can be used as an additional tool for routine treatment plan evaluation in external beam radiotherapy.
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http://dx.doi.org/10.4103/0971-6203.89965DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249729PMC
October 2011

A feasibility study of using couch-based real time dosimetric device in external beam radiotherapy.

Med Phys 2011 Dec;38(12):6539-52

Physical Sciences, Peter MacCallum Cancer Centre, Locked Bag 1, A' Beckett Street, Victoria 8006, Australia.

Purpose: Measurement of actual dose delivered during radiotherapy treatment aids in checking the accuracy of dose delivered to the patient. In this study, a couch-based real time dosimetric device has been proposed to measure the exit or entrance dose to a patient during external beam radiotherapy. The utility and feasibility of such a device using a 2D array of diodes has been demonstrated.

Methods: Two MAPCHECK devices: MAPCHECK (1175) and MAPCHECK 2 (both SunNuclear) were embedded in a foam block in the treatment couch of a Varian 21iX linear accelerator. The angular dependence of the detector response for both devices was studied before implementing the MAPCHECKs for experimental purposes. An Alderson Rando head phantom was scanned with the MAPCHECK and MAPCHECK 2 devices separately and four different treatment plans were generated with target volumes at three different positions simulating typical clinical situations. The analytical anisotropic algorithm (AAA) was used to compute the doses in an Eclipse treatment planning system (Varian Medical Systems). The Rando phantom with the MAPCHECK device was exposed in Clinac 21iX linear accelerator. The measured dose distribution was compared with the calculated dose distribution to check for the accuracy in dose delivery.

Results: Measured and computed dose distribution were found to agree with more than 93% of pixels passing at 3% and 3 mm gamma criteria for all the treatment plans. The couch-based real time dosimetry system may also be applied for noncoplanar beams where electronic portal imaging device (EPID) is not practical to measure the dose. Other advantages include checking the beam stability during the patient treatment, performing routine morning quality assurance (QA) tests in the linear accelerator, and to perform pretreatment verification of intensity modulated radiation therapy (IMRT). One of the drawbacks of this system is that it cannot be used for measuring the dose at 90° or 270° gantry angles.

Conclusions: This preliminary study shows that a 2D array of detectors may be used as part of the treatment couch for real time patient dosimetry in studying the dose delivered to the patient in real time and also for performing routine quality assurance.
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http://dx.doi.org/10.1118/1.3660773DOI Listing
December 2011

A study on the tumor volume computation between different 3D treatment planning systems in radiotherapy.

J Cancer Res Ther 2011 Apr-Jun;7(2):168-73

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

Background: Tumor volume plays a crucial role in the survival and local control of the patients treated with radiotherapy. The dose volume histogram also depends on the accuracy of the tumor delineation.

Aims: The main aim is to study the variation observed in the computation of the target volume with different treatment planning systems and treatment sites.

Materials And Methods: Sixty patients of different treatment sites which include brain, retinoblastoma, head and neck, lung, gall bladder, liver, anal canal etc, were selected for this study. The tumor volume was delineated on the Eclipse treatment planning systems and CT datasets and DICOM-RT structure sets were transferred to Pinnacle, Oncentra, Plato, Precise, Ergo++, and Tomocon contouring workstations. The recomputed volume from these planning systems was compared with the reference volume obtained from Eclipse. Similarly, the accuracy in generating PTV from CTV was also assessed with different planning systems for 5 and 10 mm.

Statistical Analysis Used: SPSS 10.0 was used for analysis.

Results: The overall comparison of the volume with different planning systems showed that Pinnacle calculated relatively larger volume followed by Plato as compared to Eclipse, whereas TOMOCON, Ergo ++, and Oncentra showed reduced volume. As far as the variation in CTV to PTV volume is concerned, pinnacle showed a relatively higher volume as compared to the Eclipse planning systems.

Conclusion: The study shows that all the treatment planning systems showed variation in computing the tumor volume and the CTV to PTV generation also varied with the planning systems.
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http://dx.doi.org/10.4103/0973-1482.82917DOI Listing
November 2011

Automatic verification of SSD and generation of respiratory signal with lasers in radiotherapy: a preliminary study.

Phys Med 2012 Jan 21;28(1):43-7. Epub 2011 Mar 21.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi 110 029, India.

Purpose: Source to surface distance (SSD) plays a very important role in external beam radiotherapy treatment verification. In this study, a simple technique has been developed to verify the SSD automatically with lasers. The study also suggests a methodology for determining the respiratory signal with lasers.

Methods: Two lasers, red and green are mounted on the collimator head of a Clinac 2300 C/D linac along with a camera to determine the SSD. A software (SSDLas) was developed to estimate the SSD automatically from the images captured by a 12-megapixel camera. To determine the SSD to a patient surface, the external body contour of the central axis transverse computed tomography (CT) cut is imported into the software. Another important aspect in radiotherapy is the generation of respiratory signal. The changes in the lasers separation as the patient breathes are converted to produce a respiratory signal. Multiple frames of laser images were acquired from the camera mounted on the collimator head and each frame was analyzed with SSDLas to generate the respiratory signal.

Results: The SSD as observed with the ODI on the machine and SSD measured by the SSDlas software was found to be within the tolerance limit. The methodology described for generating the respiratory signals will be useful for the treatment of mobile tumors such as lung, liver, breast, pancreas etc.

Conclusion: The technique described for determining the SSD and the generation of respiratory signals using lasers is cost effective and simple to implement.
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http://dx.doi.org/10.1016/j.ejmp.2011.02.002DOI Listing
January 2012

Unresectable basaloid squamous cell carcinoma of the trachea treated with concurrent chemoradiotherapy: a case report with review of literature.

J Cancer Res Ther 2010 Jul-Sep;6(3):321-3

Department of Radiotherapy and Oncology, All India Institute of Medical Sciences, New Delhi, India.

Basaloid squamous cell carcinoma is an uncommon variant of squamous cell carcinoma of the trachea. We describe the case of an unresectable basaloid squamous cell carcinoma of the trachea treated with concurrent chemoradiotherapy up to a dose of 60 Gy in 33 fractions with weekly paclitaxel and carboplatin. The pathological recognition of basaloid squamous cell carcinoma and its distinction from adenoid cystic carcinoma of the trachea is important for its management. Combining systemic chemotherapy with locoregional radiation is a logical approach to treatment, especially for the basaloid squamous cell carcinoma of the trachea, given its tendency to metastasize early after definitive therapy.
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http://dx.doi.org/10.4103/0973-1482.73341DOI Listing
March 2011

Dose volume uniformity index: a simple tool for treatment plan evaluation in brachytherapy.

J Contemp Brachytherapy 2010 Jun 6;2(2):71-75. Epub 2010 Jul 6.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi - 110 029, India.

Purpose: In radiotherapy treatment planning, dose homogeneity inside the target volume plays a significant role in the final treatment outcome. Especially in brachytherapy where there is a steep dose gradient in the dose distribution inside the target volume, comparing the plans based on the dose homogeneity helps in assessing the high dose volume inside the final treatment plan. In brachytherapy, the dose inhomogeneity inside the target volume depends on many factors such as the type of sources, placement of these radioactive sources, distance between the applicators/implant tubes, dwell time of the source, etc. In this study, a simple index, the dose volume uniformity index (DVUI), has been proposed to study the dose homogeneity inside the target volume. This index gives the total dose volume inhomogeneity inside a given prescription isoline.

Material And Methods: To demonstrate the proposed DVUI in this study, a single plane implant (breast: 6 catheters), a double plane implant (breast: 9 catheters) and a tongue implant (5 catheters) were selected. The catheters were reconstructed from the CT image datasets in the Plato treatment planning system. The doses for the single, double and tongue implants were prescribed to the reference dose rate as per the Paris technique. DVUI was computed from the cumulative dose volume histogram.

Results: For a volume receiving a uniform dose inside the prescription isoline, the DVUI is 1. Any value of DVUI > 1 shows the presence of a relatively high dose volume inside the prescription isoline. In addition to the concept of DVUI, a simple conformality index, the dose volume conformality index (DVCI), has also been proposed in this study based on the DVUI.

Conclusion: The DVUI and the proposed DVCI in this study provide an easy way of comparing the rival plans in brachytherapy.
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http://dx.doi.org/10.5114/jcb.2010.14405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5095264PMC
June 2010

A study on the variation of bladder and rectal doses with respiration in intracavitary brachytherapy for cervix cancer.

J Contemp Brachytherapy 2010 Mar 1;2(1):24-27. Epub 2010 Apr 1.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

Purpose: In cervical intracavitary brachytherapy, it is mandatory to evaluate if the doses to bladder and rectum are within tolerance limits. In this study, an effort has been made to evaluate the effect of respiration on the doses to bladder and rectum in patients undergoing brachytherapy.

Material And Methods: Fifteen patients with cervix cancer treated with concurrent chemoradiation followed by intracavitary brachytherapy were included in this study. At the time of brachytherapy, all patients underwent 4D computed tomography (CT) imaging. Five out of fifteen patients were scanned with empty bladder while the rest had full bladder during sectional imaging. Four sets of pelvic CT image datasets with applicators in place were acquired at equal interval in a complete respiratory cycle. Treatment plans were generated for all the CT datasets on a PlatoTM Sunrise planning system. A dose of 7 Gy was prescribed to Point A. Doses to ICRU (Report No.38) bladder (IBRP) and rectal (IRRP) reference points were calculated in all the CT datasets.

Results: The mean of maximum dose to IBRP at four different respiratory phases for full and empty bladder were 53.38 ± 19.20%, 55.75 ± 16.71%, 56.13 ± 17.70%, 57.50 ± 17.48% and 60.93 ± 15.18%, 60.29 ± 16.28%, 60.86 ± 15.90%, 60.82 ± 15.42% of the prescribed dose respectively. Similarly, maximum dose to IRRP for full and empty bladder were 55.50 ± 18.66%, 57.38 ± 14.81%, 58.00 ± 14.97%, 58.38 ± 17.28% and 71.96 ± 6.90%, 71.58 ± 7.52%, 68.92 ± 6.21%, 71.45 ± 7.16% respectively.

Conclusions: Our study shows that respiration affects the dose distribution to the bladder and rectum in intracavitary brachytherapy of cervix cancer. It is advisable to reduce the critical organ dose to account for the dose variation introduced by respiratory motion.
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http://dx.doi.org/10.5114/jcb.2010.13719DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5183644PMC
March 2010

Impact of patient setup error in the treatment of head and neck cancer with intensity modulated radiation therapy.

Phys Med 2010 Jan 3;26(1):26-33. Epub 2009 Jul 3.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

Purpose: To study the impact of setup errors on the dose to the target volume and critical structures in the treatment of cancer of nasopharynx with intensity modulated radiation therapy (IMRT).

Methods And Materials: Twelve patients of carcinoma of nasopharynx treated by IMRT with simultaneous integrated boost technique were enrolled. The gross tumor volume, clinical target volume and low-risk nodal region were planned for 70, 59.4 and 54 Gy, respectively, in 33 fractions. Based on the constraints, treatment plans were generated. Keeping it as the base plan, the patient setup error was simulated for 3, 5 and 10mm by shifting the isocenter in all three directions viz. anterior, posterior, superior, inferior, right and left lateral. The plans were evaluated for mean dose, maximum dose, volume of PTV receiving >110% and <93% of the prescribed dose. For both the parotids, the mean dose and the dose received by >50% of the parotid were evaluated. The maximum dose and dose received by 2 cc of spinal cord were also analyzed.

Results: The dose to the target volume decreases gradually with increase in setup error. The superior and inferior shifts play major role in tumor under-dosage. A setup error of 3mm along the posterior and lateral directions significantly affects the dose to the spinal cord. Similarly, setup error along lateral and anterior directions affects the dose to both parotids.

Conclusions: The isocenter position should be verified regularly to ensure that the goal of IMRT is achieved.
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http://dx.doi.org/10.1016/j.ejmp.2009.05.001DOI Listing
January 2010

Impact of different CT slice thickness on clinical target volume for 3D conformal radiation therapy.

Med Dosim 2009 1;34(1):36-41. Epub 2008 Apr 1.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

The purpose of this study was to present the variation of clinical target volume (CTV) with different computed tomography (CT) slice thicknesses and the impact of CT slice thickness on 3-dimensional (3D) conformal radiotherapy treatment planning. Fifty patients with brain tumors were selected and CT scans with 2.5-, 5-, and 10-mm slice thicknesses were performed with non-ionic contrast enhancement. The patients were selected with tumor volume ranging from 2.54 cc to 222 cc. Three-dimensional treatment planning was performed for all three CT datasets. The target coverage and the isocenter shift between the treatment plans for different slice thickness were correlated with the tumor volume. An important observation from our study revealed that for volume <25 cc, most of the cases were underdosed by 18% with 5-mm slice thickness and 27% with 10-mm slickness. For volume >25 cc, the target underdosage was less than 6.7% for 5-mm slice thickness and 8% for 10-mm slice thickness. For 3D conformal radiotherapy treatment planning (3DCRT), a CT slice thickness of 2.5 mm is optimum for tumor volume <25 cc, and 5 mm is optimum for tumor volume >25 cc.
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http://dx.doi.org/10.1016/j.meddos.2007.09.002DOI Listing
March 2009

A technique for verification of isocenter position in tangential field breast irradiation.

Med Dosim 2009 17;34(1):16-9. Epub 2007 Sep 17.

Department of Radiation Oncology, Institute Rotary Cancer Hospital, All India Institute of Medical Sciences, New Delhi, India.

Treatment verification and reproducibility of the breast treatment portals play a very important role in breast radiotherapy. We propose a simple technique to verify the planned isocenter position during treatment using an electronic portal imaging device. Ten patients were recruited in this study and (CT) computed tomography-based planning was performed with a conventional tangential field technique. For verification purposes, in addition to the standard medial (F1) and lateral (F2) tangential fields, a field (F3) perpendicular to the medial field was used for verification of the treatment portals. Lead markers were placed along the central axis of the 2 defined fields (F1 and F3) and the separation between the markers was measured on the portal images and verified with the marker separation on the digitally reconstructed radiographs (DRRs). Any deviation will identify the shift in the planned isocenter position during treatment. The average deviation observed between the markers measured from the DRR and portal image was 1.6 and 2.1 mm, with a standard deviation of 0.4 and 0.9 mm for fields F1 and F3, respectively. The maximum deviation observed was 3.0 mm for field F3. This technique will be very useful in patient setup for tangential breast radiotherapy.
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http://dx.doi.org/10.1016/j.meddos.2007.07.002DOI Listing
March 2009

Granulocytic sarcoma masquerading as Ewing's sarcoma: a diagnostic dilemma.

J Cancer Res Ther 2008 Jul-Sep;4(3):137-9

Department of Radiotherapy and Oncology, All India Institute of Medical Sciences, New Delhi-110 029, India.

An eleven-year-old boy presented with a swelling in his left elbow. Radiologically the features were that of an Ewing's sarcoma involving the ulna. Histopathology showed small round cell tumor strongly positive for Monoclonal Imperial Cancer research fund 2 (MIC2) antigen. Similar cells in the bone marrow were involved with MIC2 positivity. The patient developed skin lesions, which on biopsy were found to be chloromas. The initial biopsies were reevaluated with special stains revealing granulocytic sarcomas in acute myeloid leukemia masquerading as Ewing's due to its MIC2 positivity. The possibility of myeloid neoplasms should be considered routinely with known MIC2 positive round cell tumors.
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http://dx.doi.org/10.4103/0973-1482.43150DOI Listing
December 2008

Adenoid cystic carcinoma of the trachea treated with PET-CT based intensity modulated radiotherapy.

J Thorac Oncol 2008 Jul;3(7):793-5

Department of Radiotherapy and Oncology, All India Institute of Medical Sciences, New Delhi, India.

Primary tumors of the trachea are rare and are usually malignant in adults and benign in children. Adenoid cystic carcinoma, which is of salivary gland origin, account for about one thirds of adult primary tracheal tumors. A 49-year-old gentleman presented to us after undergoing a pneumonectomy elsewhere. Computed tomography scan of the thorax at our hospital showed a residual disease in the primary site, size of which was same as that in the preoperative scan. Because there was a compromised respiratory reserve due to pneumonectomy we decided to keep the radiation dose to the remaining lung as low as possible. We treated him by positron emission tomography-computed tomography (PET-CT) directed intensity modulated radiation therapy to a dose of 60 Gy in 30 Fractions over 6 weeks on a linear accelerator. PET helped in exact localization of the target on the planning CT. He tolerated the treatment very well. PET-CT done 1 year posttreatment showed no residual disease. Presently he is disease free with good pulmonary reserve.
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http://dx.doi.org/10.1097/JTO.0b013e31817c9245DOI Listing
July 2008