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ABSTRACT: MR Image Based Brachytherapy for cervical cancer was introduced in May 2006 at Tata Memorial Hospital. Our initial experience
of patients treated with MR Based Brachytherapy between May 2006 to December 2007 has been enterprising. This included guidelines
for contouring, development of MR Imaging protocol, applicator identification and reconstruction, planning, data interpretation
and reporting. This was associated with a short learning curve. In our experience, our HR-CTV volumes are higher, total doses
to D90 lower, rectal doses within tolerance limits while doses to bladder and sigmoid are higher. With this experience and
expertise, our centre has been recognized for participation in the Multicentric EMBRACE Study.
12/2010: pages 207-215;
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ABSTRACT: Small cell carcinoma of the trachea is a rare entity and only a few cases have been described, none as a second malignant neoplasm. This is the first report of a metachronous second primary of the trachea with small cell histology in a breast cancer survivor. A 25-year-old woman was diagnosed initially with an infiltrating ductal carcinoma of the breast, and was treated with modified radical mastectomy followed by adjuvant chemo-radiotherapy. 10 years later, she presented with breathlessness and central airway obstruction. Bronchoscopy revealed an intraluminal lesion in the proximal trachea, which was reported as small cell carcinoma on biopsy. There was no evidence of loco-regional recurrence of the previously treated breast cancer. Whole-body positron emission tomography did not show any distant metastases. As it was a small cell carcinoma, she was treated with concurrent chemo-radiotherapy and remains loco-regionally controlled. Decision-making in such instances should take into account prior treatment and needs to be individualized. There is a need for increased awareness amongst primary care physicians regarding second malignant neoplasms in the long-term follow-up of breast cancer patients treated with radiation and chemotherapeutic agents that have carcinogenic potential.
The British journal of radiology 05/2008; 81(964):e120-2. · 2.11 Impact Factor
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ABSTRACT: Intraoral (oral cavity and oropharynx) adenoid cystic carcinomas are uncommon cancers characterized by slow evolution, protracted clinical course, multiple and/or delayed recurrences, and late distant metastases. The molecular biology behind this enigmatic disease remains poorly characterized. To analyze and correlate prognostic factors with outcome in intraoral adenoid cystic carcinoma. Medical records of 76 patients with intraoral adenoid cystic carcinoma treated with definitive loco-regional therapy at the institute between 1992 and 2004 were retrospectively reviewed and analyzed.Majority (85.5%) of the patients had advanced stage disease. Seventy-four patients underwent surgery, of which 51 (68.9%) received adjuvant radiotherapy. The median dose of radiation was 56 Gy (range 44-66 Gy). Two patients with medical co-morbidities received radical radiotherapy. Perineural invasion, margin positivity and nodal positivity were present in 24 (32.4%); 27 (36.4%); and 15 (19.7%) patients, respectively. Ten (13.1%) patients developed local recurrence and 6 (7.8%) distant metastases. With a median follow-up of 20 months (range 1-137 months), the 5-year Kaplan-Meier estimates of local control and disease-free survival were 57.9% and 47.1%, respectively. On uni-variate analysis, perineural invasion (p=0.003), oropharyngeal primary (p=0.033), and advanced T-stage (p=0.047) were associated with increased local recurrences. Perineural invasion (p=0.05) and primary site (p=0.042) also predicted disease-free survival. On multivariate analysis, both perineural invasion and primary site retained significance for local control (p=0.007, p=0.011) and disease-free survival (p=0.018, p=0.014), respectively. Intraoral adenoid cystic carcinoma is an uncommon disease with an enigmatic clinical course. Perineural invasion, site of primary, and T-stage significantly impact upon local control and disease-free survival. The role of adjuvant radiotherapy remains controversial. Larger prospective studies with mature follow-up are needed to define the optimal treatment of intraoral adenoid cystic carcinoma.
Oral Oncology 04/2008; 44(10):986-93. · 2.86 Impact Factor
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ABSTRACT: The purpose is to compare CT-based dosimetry with International Commission on Radiation Units and Measurements (ICRU 38) bladder and rectum reference points in patients of carcinoma of uterine cervix treated with intracavitary brachytherapy (ICA). Twenty-two consecutive patients were evaluated. Orthogonal radiographs and CT images were acquired and transferred to PLATO planning system. Bladder and rectal reference points were identified according to ICRU 38 recommendations. Dosimetry was carried out based on Manchester system. Patient treatment was done using (192)Iridium high dose rate (HDR) remote after-loading machine based on the conventional radiograph-based dosimetry. ICRU rectal and bladder point doses from the radiograph plans were compared with D(2), dose received by 2 cm(3) of the organ receiving maximum dose from CT plan. V(2), volume of organ receiving dose more than the ICRU reference point, was evaluated. The mean (+/-standard deviation) volume of rectum and bladder was 60 (+/-28) cm(3) and 138 (+/-41) cm(3) respectively. The mean reference volume in radiograph and CT plan was 105 (+/-7) cm(3) and 107 (+/-7) cm(3) respectively. It was found that 6 (+/-4) cm(3) of rectum and 16 (+/-10) cm(3) of bladder received dose more than the prescription dose. V(2) of rectum and bladder was 7 (+/-1.7) cm(3) and 20.8 (+/-6) cm(3) respectively. Mean D(2) of rectum and bladder was found to be 1.11 (+/-0.2) and 1.56 (+/-0.6) times the mean ICRU reference points respectively. This dosimteric study suggests that comparison of orthogonal X-ray-based and CT-based HDR ICA planning is feasible. ICRU rectal point dose correlates well with maximum rectal dose, while ICRU bladder point underestimates the maximum bladder dose.
Journal of Medical Physics 01/2008; 33(1):3-8.
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ABSTRACT: To study the influence of various factors affecting cosmetic outcome and late sequelae in a large cohort of women treated with breast-conserving therapy.
Between 1980 and 2000, 1022 pathological stage I/II breast cancer patients underwent breast-conserving therapy. On the basis of the type of tumour bed boost they received after whole breast radiotherapy, these women were assigned to three groups: (A) low dose rate (LDR) brachytherapy of 15-20 Gy (n=383); (B) high dose rate (HDR) brachytherapy of 10 Gy (optimised) in a single fraction (n=153); (C) electron beam 15 Gy/six fractions (n=460). Systemic adjuvant therapy was given to 757 women, of whom 570 received adjuvant chemotherapy.
Cosmesis at the last follow-up was good or excellent in 77% of women. Post-radiation worsening of cosmesis was observed in 11.5% of women and was similar in the three boost groups. Moderate to severe late breast sequelae were observed in 22% of women in group B, which was significantly higher than the 12% in group A (P=0.002) and 9% in group C (P=0.0001). The actuarial 5-year local control rate was 91% and was 90, 92 and 93% in groups A, B and C, respectively. Tumour size (P=0.049) and adjuvant chemotherapy (P=0.04) were the significant factors affecting cosmetic outcome on univariate analysis. On multivariate analysis, adjuvant chemotherapy was the only factor leading to worsening in the cosmetic outcome, with P=0.03 (hazard ratio 1.65 [95% confidence interval 1.05-2.59]).
The type of tumour bed boost did not have a significant effect on the worsening of cosmetic outcome. However, there were significantly more late breast sequelae in women treated with single fraction HDR implants. Chemotherapy had an adverse effect on the cosmetic outcome, but the late breast sequelae and local control rates were comparable.
Clinical Oncology 11/2007; 19(8):596-603. · 2.07 Impact Factor
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ABSTRACT: Integrated PET/CT has emerged as an integral component of oncology management because of its unique potential of providing both functional and morphological images in a single imaging session. In this work, performance of the 'bismuth germinate (BGO) crystal'-based PET of a newly installed Discovery ST PET/CT was evaluated in 2D and 3D mode for whole-body scanning using National Electrical Manufacturers Association (NEMA) NU 2-2001 protocol and the recommended phantoms. During the entire measurements, the system operates with an energy window of 375-650 keV and 11.7 ns coincidence time window. The set of tests performed were spatial resolution, sensitivity, scatter fraction (SF) and counting rate performance. The average transaxial and axial spatial resolution measured as full width at half maximum (FWHM) of the point spread function at 1 cm (and 10 cm) off-axis was 0.632 (0.691) and 0.491 (0.653) cm in 2D and 0.646 (0.682) and 0.54 (0.601) cm in 3D respectively. The average sensitivity for the two radial positions (R = 0 cm and R = 10 cm) was 2.56 (2.63) cps/kBq in 2D and 11.85 (12.14) cps/kBq in 3D. The average scatter fraction was 19.79% in 2D and 46.19% in 3D. The peak noise equivalent counting rate (NECR) evaluated with single random subtraction was 89.41 kcps at 49 kBq/cc in 2D and 60 kcps at 12 kBq/cc in 3D acquisition mode. The NECR with delayed random subtraction was 61.47 kcps at 40.67 kBq/cc in 2D and 45.57 kcps at 16.45 kBq/cc in 3D. The performance of the PET scanner was satisfactory within the manufacturer-specified limits. The test result of PET shows excellent system sensitivity with relatively uniform resolution throughout the FOV, making this scanner highly suitable for whole-body studies.
Journal of Medical Physics 10/2007; 32(4):150-5.
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ABSTRACT: A new model of the telecobalt unit (TCU), Theratron Equinox-80, (MDS Nordion, Canada) equipped with a single 60 degree motorized wedge (MW), four universal wedges (UW) for 15 degrees, 30 degrees, 45 degrees and 60 degrees have been evaluated. MW was commissioned in Eclipse (Varian, Palo Alto, USA) 3D treatment planning system (TPS). The profiles and central axis depth doses (CADD) were measured with Wellhofer blue water phantom for MW and the measured data was commissioned in Eclipse. These profiles and CADD for MW were compared with UW in a homogeneous phantom generated in Eclipse for various field sizes. The dose was also calculated in the same phantom at 10 cm depth. For the particular MW angle and the respective open and MW beam weights, the dose was measured for a field size of 10 cm x 10 cm in a MEDTEC water phantom at 10 cm depth with a 0.13 cc thimble ion chamber (Scanditronix Wellhofer, Uppsala, Sweden) and a NE electrometer (Nuclear Enterprises, UK). Measured dose with ion chamber was compared with the TPS calculated dose. MW angle verification was also done on the Equinox for four angles (15 degrees, 30 degrees, 45 degrees and 60 degrees). The variation in measured and calculated dose at 10 cm depth was within 2%. The measured and the calculated wedge angles were in good agreement within 2 degrees. The motorized wedges were successfully commissioned in Eclipse for four wedge angles.
Australasian physical & engineering sciences in medicine / supported by the Australasian College of Physical Scientists in Medicine and the Australasian Association of Physical Sciences in Medicine 07/2007; 30(2):127-34. · 0.56 Impact Factor
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ABSTRACT: Head and neck squamous cell carcinoma (HNSCC) continues to be a leading cancer in developing countries. Definitive radiation therapy either primary or as postoperative adjuvant is offered to most patients. We aimed to identify prognostic and therapeutic factors that affect locoregional control and survival in patients undergoing radical radiotherapy for head and neck squamous cell cancers.
A retrospective analysis of 568 previously untreated patients with squamous head and neck cancers, who received radical radiotherapy between 1990 and 1996, using local control, locoregional control and disease-free survival (DFS) as outcome measures.
With a median follow-up of 18 months for living patients, the 5-year local control, locoregional control and DFS for all 568 patients were 53%, 45% and 41%, respectively, for all stages combined. The 5-year local control, locoregional control and DFS as per the American Joint Committee on Cancer stage grouping were 78%, 70% and 70%; 64%, 59% and 57%; 51%, 42% and 37%; and 40%, 27% and 22% from stages I to IV, respectively, with highly significant P values. Patients receiving higher doses (> or = 66 Gy) had a significantly better outcome compared with lower doses. The 5-year local control (59% vs 48%, P = 0.0015), locoregional control (47% vs 41%; P = 0.0043) and DFS (44% vs 37%; P = 0.0099) were significantly better in patients receiving > or = 66 Gy. Site of primary also affected outcome significantly, with oral cavity lesions faring badly.
Tumour stage remains the most important factor affecting outcome in radical radiotherapy of HNSCC. A definite dose-response relationship exists with higher total doses, leading to better local control, locoregional control and DFS in all stages. Site of primary affects outcome too, with laryngeal primaries doing well and oral cavity cancers faring the worst.
Clinical Oncology 07/2006; 18(5):383-9. · 2.07 Impact Factor
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ABSTRACT: The increase in the number of monitor units in sliding window intensity-modulated radiotherapy, compared with conventional techniques for the same target dose, may lead to an increase in peripheral dose (PD). PD from a linear accelerator was measured for 6 MV X-ray using 0.6 cm3 ionization chamber inserted at 5 cm depth into a 35 cm x 35 cm x 105 cm plastic water phantom. Measurements were made for field sizes of 6 cm x 6 cm, 10 cm x 10 cm and 14 cm x 14 cm, shaped in both static and dynamic multileaf collimation (DMLC) mode, employing strip fields of fixed width 0.5 cm, 1.0 cm, 1.5 cm, and 2.0 cm, respectively. The effect of collimator rotation and depth of measurement on peripheral dose was investigated for 10 cm x 10 cm field. Dynamic fields require 2 to 14 times the number of monitor units than does a static open field for the same dose at the isocentre, depending on strip field width and field size. Peripheral dose resulting from dynamic fields manifests two distinct regions showing a crest and trough within 30 cm from the field edge and a steady exponential fall beyond 30 cm. All dynamic fields were found to deliver a higher PD compared with the corresponding static open fields, being highest for smallest strip field width and largest field size; also, the percentage increase observed was highest at the largest out-of-field distance. For 6 cm x 6 cm field, dynamic fields with 0.5 cm and 2 cm strip field width deliver PDs 8 and 2 times higher than that of the static open field. The corresponding factors for 14 cm x 14 cm field were 15 and 6, respectively. The factors by which PD for DMLC fields increase, relative to jaws-shaped static fields for out-of-field distance beyond 30 cm, are almost the same as the corresponding increases in the number of monitor units. Reductions of 20% and 40% in PD were observed when the measurements were done at a depth of 10 cm and 15 cm, respectively. When the multileaf collimator executes in-plane (collimator 90 degrees) motion, peripheral dose decreases by as much as a factor of 3 compared with cross-plane data. The knowledge of PD from DMLC field is necessary to estimate the increase in whole-body dose and the likelihood of radiation induced secondary malignancy.
British Journal of Radiology 05/2006; 79(940):331-5. · 1.31 Impact Factor
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ABSTRACT: The purpose of this study is to compare geometric optimization (GO) with anatomy based inverse optimization (ABIO). Five patients of carcinoma prostate treated with HDR interstitial brachytherapy had been studied. Post implant CT scans of 5 mm slice thickness were obtained; target volume and other critical structures rectum, bladder and urethra were drawn by the clinician. Plans were obtained with geometric optimization and anatomy based inversed optimization. Anatomy based inverse planning implemented currently in PLATO BPS version 14.2, is based on geometric and dose point optimization and designed to account for the critical structures. Graphical optimization (GrO) is used to fine-tune the distribution ie to reduce the dose to critical structures and to improve the target coverage in both geometric optimization and anatomy based inverse optimization plans. DVH of target, rectum, bladder and urethra were evaluated and compared, dose homogeneity index and conformity index were also evaluated for all the plans. The mean target coverage was 93.9±7%, 90.3±4%, 82±13%, 91.6±3 for different optimization techniques GO, GO_gr, ABIO and ABIO_gr respectively. The target coverage in ABIO is not clinically acceptable. Maximum dose, dose to 2% of the volume of urethra D(2%,U) was 137±12%, 123.2±2%, 111.5±9, 122.7±4 for GO, GO_gr, ABIO and ABIO_gr respectively. The mean conformity index values were 0.71, 0.76, 0.65, 0.82 for GO, GO_gr, ABIO, ABIO_gr respectively. ABIO_gr has a good conformity over all other optimization techniques. However the difference is not very significant between GO and GO_gr. The mean values of DHI are 0.81, 0.77, 0.65 and 0.75 for GO, GO_gr, ABIO and ABIO_gr respectively. Geometric optimization is highly homogenous compared to all other optimization techniques.To conclude, target coverage in ABIO is not clinically acceptable. However ABIO followed by graphical optimization is much superior in sparing of critical structures and conformity compared to geometrical optimization. Target coverage is marginally better in GO compared to ABIO_gr. Homogeneity is superior in GO compared to ABIO_gr. However ABIO_gr plans were clinically acceptable with respect to homogeneity. Further, dose escalation to the target is possible with ABIO, without exceeding the tolerance dose to urethra. Clinical correlation of genitourinary toxicity has to be studied.
Journal of Medical Physics 04/2006; 31(2):89-94.
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ABSTRACT: Limited information is available about the sonomorphological changes in metastatic neck nodes during radiotherapy. The aim of this study was to evaluate the pattern of sonomorphological changes in metastatic neck nodes with radiotherapy. The study population consisted of 16 consecutive patients planned for radical radiotherapy to the head and neck. All patients were subjected to four ultrasound examinations: before therapy, at 46 Gy, at the conclusion of radiation and at first follow up. A total of 59 ultrasound examinations were performed on 16 patients. The difference between the mean number of nodes detected per patient before (10.6) and after (7.8) radiation was significant (P = 0.05). Sixteen nodes were categorized as malignant at first sonography, half of which reverted back to normal by the end of radiation. Changes in the sonomorphology of malignant cervical lymph nodes occur with radiotherapy with more that half demonstrating reversion to normal pattern. Future studies correlating this with histopathology should be considered.
Australasian Radiology 05/2005; 49(2):113-8. · 0.51 Impact Factor
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ABSTRACT: Stereotactic Radiotherapy (SRT) is an advancement on three-dimensional conformal radiotherapy (3DCRT) which aims not only to conform the therapeutic dose volume to the shape of the tumor, but also ensures low dose to the other normal tissues. As the therapeutic dose volume tightly covers the tumor, small variation between intended plan and executed plan parameters may lead to significant under-dose of tumor or over-dose of normal tissue, which may result in the failure of the treatment. Therefore, SRT should be carried out through a well-laid out systematic procedure in order to achieve its goal. This paper highlights the systematic procedure and comprehensive Quality Assurance (QA) involved at various steps of intracranial SRT followed in our hospital and our preliminary experience with Brain Lab Stereotactic System. Of the 18 patients treated so far with SRT, we have analyzed the SRT treatment plans for the first 11 brain tumor patients to highlight the volume of tumor covered by the therapeutic dose and integral dose to other normal tissues. The average Gross Target Volume (GTV) and Planning Target Volume (PTV) treated are 14.07 cc and 43.72 cc, respectively. Out of the 11 patients treated, 100% volume of PTV is covered by 95% isodose volume in 4 patients, 99% of PTV in another 4 patients and 98% of PTV in the remaining 3 patients. But in all the cases, a minimum volume of 96% of the GTV is adequately covered by 100% dose. The conformity index of PTV varies from 1.27 to 1.56, with a mean value of 1.42. As the target volume decreases from 76 cc to 20 cc, the mean dose within the target volume increases from 1.7 Gy to 1.76 Gy. The average volume of normal brain treated with 80%, 50% and 33% dose are 6.53 cc, 73 cc and 298 cc, respectively. Stereotactic radiotherapy with static beams and micro-Multileaf Collimator (mMLC) shaped fields gives the flexibility to tailor the irregular shaped target volume, thereby ensuring better dose conformity and homogeneous dose distribution. Precise delivery of the therapeutic dose to the tumor needs comprehensive quality assurance, both at machine and patient levels.
Journal of Medical Physics 01/2002; 27(1):1-8.
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ABSTRACT: To assess local control, survival and complications in patients with cervical carcinoma Stage IIB treated radically with transperineal Iridium-192 low-dose rate interstitial brachytherapy following external beam radiotherapy.
65 women (age 25-70 years, mean 47 years) with cervical carcinoma Stage IIB were initially treated with external beam radiotherapy on a telecobalt or 6 MV linear accelerator to a dose of 50 Gy delivered in 5-6 weeks. After 2-3 weeks of completing external radiation, patients received interstitial brachytherapy with Iridium-192 (activity 0.5-1 mCi/cm) using a Syed-Neblett perineal template. The median dose delivered to the implant volume was 24 Gy (range 20-32 Gy) delivered at an average dose rate of 0.70 Gy/h (range 0.40-1.20 Gy/h). A point defined at 1.5 cm lateral to the central uterine tandem at the level of os was taken as a representative for assessing the dose to the cervix. Mean doses delivered by interstitial brachytherapy to point A, cervix, point B and rectum were 38 Gy, 34 Gy, 16 Gy and 16 Gy, respectively.
At a median follow-up of 53 months, the actuarial disease free survival and overall survival for 65 patients at both 5 and 10 years was 64% and 44%, respectively. Response to radiotherapy was a strong predictor of local control with 82% of patients continuing to have pelvic control after initial complete response. Overall, nine (14%) patients had persistent disease, ten (15%) developed a central recurrence after initial control and three patients developed distant metastasis on follow-up. No patient had any immediate treatment-related complication. Late toxicity included grade I-II rectal reactions in five patients and grade IV bladder complication (vesico-vaginal fistula) in two patients. 5 years after treatment, one patient developed intestinal obstruction, which was relieved after conservative management. Two patients developed vaginal stenosis. The 5- and 10-year disease free survival was 48% in patients aged less than 45 years as compared to 80% in patients of more than 45 years (p = 0.009). Dose to the cervical point was a prognostic indicator with 5- and 10-year disease free survival of 47% in patients who received < 35 Gy in comparison to 80% in patients who had > 35 Gy (p = 0.03). There was no difference in local control and survival in patients with minimal and moderate parametrial involvement. Bulky disease (> 4 cm) at presentation and a longer gap between external radiation and brachytherapy showed a trend towards inferior local control.
Interstitial brachytherapy after external beam irradiation in patients with cervical carcinoma Stage IIB results in acceptable local control, survival and complication rates. Increased dose to the cervical disease results in improved local control and survival and should therefore be considered while optimizing brachytherapy treatment plans. Comparison of the results with those of standard intracavitary therapy remains to be proven in a randomized trial.
Strahlentherapie und Onkologie 11/2001; 177(10):517-24. · 3.56 Impact Factor
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ABSTRACT: Low-grade B-cell mucosa associated lymphoid tissue (MALT) lymphoma can rarely present primarily in extranodal sites other than stomach, which is the most common site for it. Until now only four cases of primary prostatic MALTomas have been described in the literature and we report the fifth. We describe a case of primary prostatic MALToma in a 67-year-old man and the diagnosis was made on the trans-urethral resection specimen of the prostate. As the disease was limited to prostate (stage IEA), the patient was treated with external beam radiation therapy to a total dose of 4400cGy in 22 fractions. The patient achieved completed remission and has remained free of disease in the following 36 months.
Leukemia and Lymphoma 05/2001; 41(3-4):445-9. · 2.58 Impact Factor
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ABSTRACT: Carcinoma of the vagina is a rare gynecological malignancy comprising approximately 2% of all the gynecological malignancies. We have analyzed the treatment outcome of the patients treated at the Tata Memorial Hospital from January 1984 to December 1993.
In this 10-year period, 134 patients of primary vaginal cancers were registered at our hospital. Of these, 75 patients received complete treatment and are analyzed.
Disease-free survival (DFS) for the whole group is 50%, and overall survival (OAS) is 60%. Most locoregional recurrences and distant failures are noted in the 2 years following treatment. DFS at 5 years is as follows: Stage I (5 patients), Stage IIA (37 patients), Stage IIB (15 patients), Stage III (14 patients), and Stage IV (4 patients); are 40%, 55%, 60%, 50%, and 25%, respectively. The DFS for patients with complete response (42 patients) to external radiation at 5 years is 68%, with partial response (25 patients) is 35%, and with poor or no response (6 patients) is 18% (p = 0.0000). We observed that brachytherapy was an important part of the treatment, and patients who received brachytherapy (59 patients), either with a vaginal intracavitary applicator (30 patients) or interstitial implant (29 patients) had a DFS of 53% and 56%, respectively, while 15 patients who received external radiation alone had a DFS of 30%. Patients receiving brachytherapy within 4 weeks of external radiation had a DFS of 60% as compared to 30% when the interval was more than 4 weeks.
The factors indicating prognosis are: site and extent of involvement, presence of lymph nodes at presentation, technique of brachytherapy, and interval between external radiation and brachytherapy.
International Journal of Radiation OncologyBiologyPhysics 02/2000; 46(1):101-8. · 4.11 Impact Factor
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ABSTRACT: Design of an universal wedge shaped midline block for early stage cervical cancers to get uniform dose distribution around the target volume.
The method of fabrication of wedge shaped midline block is discussed for treatment of early stage cervical cancers based on the configuration of 137Cs pellets used in intracavitary applications and along with external photon beams obtained by using 60Co teletherapy machine and 6 and 10 MV linear accelerators.
The dosimetric measurements are carried out to confirm the adequacy of thickness and shape of the block using radiation field analyzer for all the 3 energies.
The dose distribution comparison has been made with wedge shaped midline block and conventional rectangular shields to show its superiority in getting homogeneous dose distribution around target volume. The shift in 184 intracavitary applications is analyzed in actual clinical applications with respect to central axis of external beams and its comparison is made with both types of blocks. With the shift of 1 cm towards lateral from midline an overdose can occur upto 12 Gy at certain points with rectangular block compared to wedge shaped midline block.
Since the preparation of individual wedge shaped midline block for every application will be a difficult process for busy centers, the single wedge shaped midline block for each energy is more convenient to handle for busy centers instead of individualized compensating blocks for every intracavitary application.
Strahlentherapie und Onkologie 01/1997; 172(12):676-80. · 3.56 Impact Factor
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ABSTRACT: The present work was aimed at to study the relationship between the volume enclosed by reference isodose surface and various geometrical parameters of the intracavitary applicator in treatment of carcinoma of cervix.
Pearshape volume of the reference isodose derived from the Total Reference Air Kerma (TRAK) and the product of its dimensions, height H, width W and thickness T which is dependent on the applicator geometry, were estimated for 100 intracavitary applications treated by Selectron LDR machine. Orthogonal radiographs taken for each patient were used for measurement of actual geometric dimensions of the applicator and carrying out the dosimetry on TP-11 treatment planning system. The dimensions H, W and T of reference isodose surface (60 Gy) were also noted.
Ratio of the product HWT and the pearshape volume was found mainly to be a function of colpostat separation and not of other geometrical parameters like maximum vertical and anterio-posterior dimension of the applicator. The ratio remained almost constant for a particular combination of uterine tandem and colpostat. Variation in the ratios were attributed to the non-standard geometry.
The ratio of the volume of reference isodose surface to the product of its dimensions in the applicator depends upon the colpostat separation.
Strahlentherapie und Onkologie 07/1996; 172(6):326-9. · 3.56 Impact Factor
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ABSTRACT: Among the various infrequent causes of Pancoast's syndrome, Hodgkin's disease is one. A 26 year old man was diagnosed as Hodgkin's disease. Five years later the disease relapsed producing Pancoast's syndrome. The importance of precise aetiological diagnosis before treatment of such cases with similar presentation is emphasized.
Indian Journal of Cancer 04/1996; 33(1):21-3.
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ABSTRACT: A systematic dosimetry study conforming to International Commission on Radiation Units and Measurements Report Number 38, was carried out for, cancer of Cervix Stage I and II cases at Tata Memorial Hospital.
The reference Volume dimension were noted for each applicator. Also 3-D dosimetry was performed for selected cases, and actual geometric volume enclosed by various isodose surfaces were obtained. A relation was derived, which gave the volume enclosed by any isodose surface as a function of total reference air kerma of the sources in the applicator. The volume enclosed by reference isodose surface was compared with the product of its dimensions height, width, and thickness.
The volume enclosed by any isodose surface of an intracavitary application can be easily derived from total reference air kerma of the sources within the applicator.
Ratio of the volume enclosed by reference isodose surface with the product of its dimensions (HWT) could be a predictive parameter for clinical outcome, besides the reference volume specified by the report.
International Journal of Radiation OncologyBiologyPhysics 02/1994; 28(2):499-504. · 4.11 Impact Factor
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ABSTRACT: To investigate the impact of clinical and physical parameters on the cosmetic result and complications, in cancer breast treated with conservative surgery and definitive irradiation.
Between October 1980 and December 1990, 289 patients were treated with lumpectomy and/or axillary dissection, radical irradiation with or without adjuvant therapy. The radiation therapy technique consisted of external beam therapy followed by an Ir-192 implant or electron beam boost. Univariate and multivariate analysis were used to evaluate the correlation between multiple factors affecting the cosmetic outcome and the complications.
Of 289 patients, cosmesis was evaluable in 285 and recorded as excellent to good in 226 (79%), fair in 35 (12%), and poor in 24 (9%). On multivariate analysis of these results, a high dose per fraction (p = .0018), and use of electrons as boost to the tumor bed (p = .001) were found to be significant. When patients boosted with electrons were excluded, a high boost dose (p = .0433) was also found significant. Fifteen (5%) patients developed severe late radiation sequelae and 14 (5%) moderate or severe arm edema. On multivariate analysis only dose per fraction of 2.5 Gy (p < .0001) and higher boost doses (p = .017) were significant.
In 289 patients of early breast cancer treated with conservative surgery and radical irradiation, multivariate analysis suggests that higher dose per fraction with teletherapy and higher brachytherapy boost dose adversely affect cosmesis and contribute to the late complications.
International Journal of Radiation OncologyBiologyPhysics 09/1993; 27(2):285-92. · 4.11 Impact Factor
