M.A. Laviraj

Early Clinical Outcomes and Toxicity of Intensity Modulated Versus Conventional Pelvic Radiation Therapy for Locally Advanced Cervix Carcinoma: A Prospective Randomized Study

PURPOSE To evaluate the toxicity and clinical outcome in patients with locally advanced cervical cancer (LACC) treated with whole pelvic conventional radiation therapy (WP-CRT) versus intensity modulated radiation therapy (WP-IMRT). METHODS AND MATERIALS Between January 2010 and January 2012, 44 patients with International Federation of Gynecology and Obstetrics (FIGO 2009) stage IIB-IIIB squamous cell carcinoma of the cervix were randomized to receive 50.4 Gy in 28 fractions delivered via either WP-CRT or WP-IMRT with concurrent weekly cisplatin 40 mg/m(2). Acute toxicity was graded according to the Common Terminology Criteria for Adverse Events, version 3.0, and late toxicity was graded according to the Radiation Therapy Oncology Group system. The primary and secondary endpoints were acute gastrointestinal toxicity and disease-free survival, respectively. RESULTS Of 44 patients, 22 patients received WP-CRT and 22 received WP-IMRT. In the WP-CRT arm, 13 patients had stage IIB disease and 9 had stage IIIB disease; in the IMRT arm, 12 patients had stage IIB disease and 10 had stage IIIB disease. The median follow-up time in the WP-CRT arm was 21.7 months (range, 10.7-37.4 months), and in the WP-IMRT arm it was 21.6 months (range, 7.7-34.4 months). At 27 months, disease-free survival was 79.4% in the WP-CRT group versus 60% in the WP-IMRT group (P=.651), and overall survival was 76% in the WP-CRT group versus 85.7% in the WP-IMRT group (P=.645). Patients in the WP-IMRT arm experienced significantly fewer grade ≥2 acute gastrointestinal toxicities (31.8% vs 63.6%, P=.034) and grade ≥3 gastrointestinal toxicities (4.5% vs 27.3%, P=.047) than did patients receiving WP-CRT and had less chronic gastrointestinal toxicity (13.6% vs 50%, P=.011). CONCLUSION WP-IMRT is associated with significantly less toxicity compared with WP-CRT and has a comparable clinical outcome. Further studies with larger sample sizes and longer follow-up times are warranted to justify its use in routine clinical practice.

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

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.

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

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.

Role of extracorporeal irradiation in malignant bone tumors.

AIMS AND OBJECTIVES Extracorporeal irradiation (ECI) is relatively a rare method used in the management of malignant bone tumors (MBT). It consists of en-bloc removal of the tumor bearing bone segment, removal of the tumor from the bone, irradiation, and re-implantation back in the body. We report our preliminary experience of using ECI for management of MBT. MATERIALS AND METHODS From year 2009 to 2010, 14 patients with primary MBT were enrolled into this study. The eligibility criteria included histopathological proof of malignancy, no evidence of distant metastases, and suitability for limb preservation therapy. Surgery was performed about 4 weeks after completion of neoadjuvant chemotherapy. The affected bone segment was resected, irradiated extracorporeally with a dose of 50 Gy and reimplanted. Local control, complications and short-term survival were studied. Functional outcome was assessed by Musculoskeletal Tumor Society (MSTS) scoring system. RESULTS There were 10 males and four females with median age of 14 years. Histopthologically, nine patients had osteosarcoma (OS) and five had Ewings sarcoma family of tumors (ESFT). Distribution of primary site was as follows: Femur eight patients, tibia five patients and humerus one patient. At a median follow-up was 22 months, three patients (two OS, one ESFT) had local recurrence. Two patients (14%) developed wound infection in the perioperative period. The 2 year local recurrence free survival was 73% and mean MSTS score was 88. CONCLUSION Results of our study suggest that ECI is technically feasible in the management of MBT and provides decent local control and short-term survival rates.

Modern chemoradiation practices for malignant tumors of the trachea: An institutional experience.

Background: Malignant tumors of the trachea are rare. A multimodality treatment approach is often necessary. Outcomes of radical non-surgical approaches are sparse. Radiation combined with sequential or concurrent chemotherapy is an important treatment option. Materials and Methods: We present an analysis of outcomes using modern radiotherapy and chemotherapy for tracheal tumors. Results: Radiation dose escalation using modern techniques is of benefit for these tumors. The results with chemotherapy are encouraging. Conclusions: Radiation plays a distinct role and should be a part of treatment for these tumors. The role of chemotherapy needs to be studied further.

MAGAT gel dosimetry for its application in small field treatment techniques

Purpose of this work is to present the role of in-house manufactured MAGAT gel for treatment verification in small field dosimetric techniques such as Gammaknife (GK) and intensity-modulated radiation therapy (IMRT). Magnetic resonance imaging (MRI) is one of the most extensively used imaging technique for polymer gel dosimetry hence we used this method for gel evaluation. Different MR scanners and MRI sequences were used in this study for obtaining calibration plot between R2 and absorbed dose. An experimental plan was created for Gammaknife and IMRT. The prepared gel was filled in spherical glass phantom and in-house designed human head shape phantom for verification purpose. We used 8 TE values for all the imaging sequences for two reasons. Firstly it is sufficient enough to give good signal to noise ratio. Second considering the enormous scanning time involved in multiple spin echo sequence. MATLAB based in-house programs were used for R2 estimation and dose comparison. The isodose comparison with MAGAT gel showed reasonable agreement for both Gammaknife and IMRT techniques.

CommentIn Regard to Ge et al

To the Editor: In the study by Ge et al (1), the authors have meticulously studied the relationships between the gross tumor volume (GTV) based on free-breathing, internal target volume (ITV)eall phases, and ITVeMIP (maximum intensity projections). With the advent of four-dimensional computed tomography (4D-CT) the issue of tumor motion has been accounted for, yet the optimum method for 4D-CT-based target delineation is not known (2). The various methods include use of MIP, contouring in all 10 phases, or contouring in maximum inhalation and exhalation phases (3). The contouring of ITV in all phases is considered the standard but is time consuming. The use of MIP has been shown to underestimate the volumes when compared with ITV based on all phases (4). As per the conclusions of this study, by combining information from three-dimensional CT (3D-CT), 4D-CT, and MIP, the uncertainties could be minimized. This cannot, however, be considered effective in terms of time consumed, especially for the target delineation alone. The authors have proposed that because the combination of ITV (MIP) and GTV (3D) was not statistically different from ITVeall phases in terms of volume, they can be effectively used instead of contouring ITV in all phases. In the present study all six volumes (GTV [3D] and ITV1 to ITV5 based on MIP) were delineated in the same lung window by the same radiation oncologist. The MIP images are derived from composite images with different image quality when compared with 3D-CT images (5). In a retrospective analysis based on 5 patients with early-stage non-small cell lung cancer treated with stereotactic body radiation therapy at our institution, we have found that the CT thresholds used for contouring on the MIP images can significantly change the ITV volumes. The ITV on MIP with conventional lung CT window/levels (1600 Hounsfield Units [HU]/ 300 HU) correlated poorly (rZ0.83, PZ.04) with ITVeall phases, whereas the ITV delineated on MIP with CT window/levels of 1600 HU/ 450 HU correlated best (rZ0.9, PZ.01). The maximal diameter also correlated better with CT window/level thresholds of 1600 HU/ 450 HU (rZ0.97, PZ.001) than the conventional thresholds (rZ0.82,

Quantification and minimization of uncertainties of internal target volume for stereotactic body radiation therapy of lung cancer: in regard to Ge et al.

To the Editor: In the study by Ge et al (1), the authors have meticulously studied the relationships between the gross tumor volume (GTV) based on free-breathing, internal target volume (ITV)eall phases, and ITVeMIP (maximum intensity projections). With the advent of four-dimensional computed tomography (4D-CT) the issue of tumor motion has been accounted for, yet the optimum method for 4D-CT-based target delineation is not known (2). The various methods include use of MIP, contouring in all 10 phases, or contouring in maximum inhalation and exhalation phases (3). The contouring of ITV in all phases is considered the standard but is time consuming. The use of MIP has been shown to underestimate the volumes when compared with ITV based on all phases (4). As per the conclusions of this study, by combining information from three-dimensional CT (3D-CT), 4D-CT, and MIP, the uncertainties could be minimized. This cannot, however, be considered effective in terms of time consumed, especially for the target delineation alone. The authors have proposed that because the combination of ITV (MIP) and GTV (3D) was not statistically different from ITVeall phases in terms of volume, they can be effectively used instead of contouring ITV in all phases. In the present study all six volumes (GTV [3D] and ITV1 to ITV5 based on MIP) were delineated in the same lung window by the same radiation oncologist. The MIP images are derived from composite images with different image quality when compared with 3D-CT images (5). In a retrospective analysis based on 5 patients with early-stage non-small cell lung cancer treated with stereotactic body radiation therapy at our institution, we have found that the CT thresholds used for contouring on the MIP images can significantly change the ITV volumes. The ITV on MIP with conventional lung CT window/levels (1600 Hounsfield Units [HU]/ 300 HU) correlated poorly (rZ0.83, PZ.04) with ITVeall phases, whereas the ITV delineated on MIP with CT window/levels of 1600 HU/ 450 HU correlated best (rZ0.9, PZ.01). The maximal diameter also correlated better with CT window/level thresholds of 1600 HU/ 450 HU (rZ0.97, PZ.001) than the conventional thresholds (rZ0.82,

In Regard to Ge et al

To the Editor: In the study by Ge et al (1), the authors have meticulously studied the relationships between the gross tumor volume (GTV) based on free-breathing, internal target volume (ITV)eall phases, and ITVeMIP (maximum intensity projections). With the advent of four-dimensional computed tomography (4D-CT) the issue of tumor motion has been accounted for, yet the optimum method for 4D-CT-based target delineation is not known (2). The various methods include use of MIP, contouring in all 10 phases, or contouring in maximum inhalation and exhalation phases (3). The contouring of ITV in all phases is considered the standard but is time consuming. The use of MIP has been shown to underestimate the volumes when compared with ITV based on all phases (4). As per the conclusions of this study, by combining information from three-dimensional CT (3D-CT), 4D-CT, and MIP, the uncertainties could be minimized. This cannot, however, be considered effective in terms of time consumed, especially for the target delineation alone. The authors have proposed that because the combination of ITV (MIP) and GTV (3D) was not statistically different from ITVeall phases in terms of volume, they can be effectively used instead of contouring ITV in all phases. In the present study all six volumes (GTV [3D] and ITV1 to ITV5 based on MIP) were delineated in the same lung window by the same radiation oncologist. The MIP images are derived from composite images with different image quality when compared with 3D-CT images (5). In a retrospective analysis based on 5 patients with early-stage non-small cell lung cancer treated with stereotactic body radiation therapy at our institution, we have found that the CT thresholds used for contouring on the MIP images can significantly change the ITV volumes. The ITV on MIP with conventional lung CT window/levels (1600 Hounsfield Units [HU]/ 300 HU) correlated poorly (rZ0.83, PZ.04) with ITVeall phases, whereas the ITV delineated on MIP with CT window/levels of 1600 HU/ 450 HU correlated best (rZ0.9, PZ.01). The maximal diameter also correlated better with CT window/level thresholds of 1600 HU/ 450 HU (rZ0.97, PZ.001) than the conventional thresholds (rZ0.82,

A comparative analysis of single objective dose volume histogram (SDVHO)–based inverse planning optimization versus volume-based geometric optimization in real-time prostate brachytherapy planning with Oncentra Prostate.

e15109 Background: Ultrasound-based real time HDR brachytherapy planning is a recent advance in prostate brachytherapy. There are a number of optimization methods in Oncentra Prostate (previously SWIFT). We have compared two most important optimization methods: single objective dose volume histogram-based inverse planning optimization (SDVHO-IP) versus volume-based geometric optimization (VBGO). METHODS Five patients of localized prostate cancer were chosen for this planning study. They underwent a planning transrectal ultrasound scan on the Oncentra Prostate. Prostate (PTV), bladder, rectum and urethra were contoured on all slices. Two plans: one with SDVHO-IP and other with VBGO were generated for each patient. Plan comparison was done for PTV coverage and critical organ doses. For the PTV, D100 and D90 which is the dose received by 100 and 90 % of the target volume respectively are calculated. Also V100, V90 and V200 which are the volume of the prostate receiving 100, 90 and 200% of prescribed dose are also calculated. For bladder and rectum V75 which is the volume receiving 75% of the prescribed dose and for the urethra V125 which is the volume of urethra receiving 125% of the prescribed dose is calculated. COIN index was also compared. SPSS Version 14 software used p value to compare means. RESULTS The table shows that SDVHO-IP provides better target coverage and conformity than VBGO. But there is no difference as far as dose to the critical organs are concerned. CONCLUSIONS Single objective dose volume histogram-based inverse planning optimization is superior to volume-based geometric optimization. Inverse planning with oncentra prostate needs to be encouraged. [Table: see text].