Impact of three-dimensional chemoradiation on pelvic bone mineral density, low back pain, and disability in cervical cancer: a prospective study.

OBJECTIVE: To prospectively analyze the effect of three-dimensional chemoradiation on the bone mineral density of pelvic bones and its association with low back pain and disability in patients with locally advanced cervical cancer. METHODS: In biopsy proven locally advanced cervical cancer patients, bone mineral density and T scores for lumbar vertebrae 5, dorsal thoracic vertebrae 12, and T scores for the femoral neck were analyzed. Low back pain was scored using the visual analog scale while disability scoring was done using the Oswestry low back pain disability scale. Furthermore, a subgroup analysis for patients (classified according to menopausal status) was performed. RESULTS: In total, 106 patients were analyzed. A statistically significant decline in mean bone mineral density was observed at all three sites (vertebrae 5 and 12, and the femoral neck) post-chemoradiation therapy compared with pretreatment bone mineral density (0.671 vs 0.828, -2.083 vs -1.531, -2.503 vs -1.626; all p<0.001). Similarly, in subgroup analyses, at all three sites, pre-menopausal patients showed a statistically significant association (0.876 vs 0.697, -1.203 vs -0.2.761, -1.403 vs -2.232; all p<0.001) while a non-significant association was observed for post-menopausal patients at vertebrae 12 (-1.707 vs -1.719; p=0.09) with a statistically significant association at vertebrae 5 and the femoral neck (0.803 vs 0.656, -1.746 vs -2.648; p<0.01). Although statistically significant low back pain and disability scores were observed overall and irrespective of menopausal status, no correlation between bone mineral density and low back pain and disability was observed. CONCLUSION: Pelvic bone mineral density decreases significantly after chemoradiation, irrespective of menopausal status. However, no correlation with low back pain and disability was observed. Pelvic bone mineral density analysis should be considered before chemoradiation in cervical cancer.

Dosimetric impact of contrast-enhanced 4d computed tomography for stereotactic body radiation therapy of hepatocelluar carcinoma.

BACKGROUND: A purpose of the study was to investigate the dosimetric impact of contrast media on dose calculation using average 4D contrast-enhanced computed tomography (4D-CECT) and delayed 4D-CT (d4D-CT) images caused by CT simulation contrast agents for stereotactic body radiation therapy (SBRT) of liver cases. MATERIALS AND METHODS: Fifteen patients of liver SBRT treated using the volumetric modulated arc therapy (VMAT) technique were selected retrospectively. 4D-CECT, and d4D-CT were acquired with the Anzai gating system and GE CT. For all patients, gross target volume (GTV) was contoured on the ten phases after rigid registration of both the contrast and delayed scans and merged to generate internal target volume (ITV) on average CT images. Region of interest (ROI) was drawn on contrast images and then copied to the delayed images after rigid registration of two average CT datasets. The treatment plans were generated for contrast enhanced average CT, delayed average CT and contrast enhanced average CT with electron density of the heart overridden. RESULTS: No significant dosimetric difference was observed in plans parameters (mean HU value of the liver, total monitor units, total control points, degree of modulation and average segment area) except mean HU value of the aorta amongst the three arms. All the OARs were evaluated and resulted in statistically insignificant variation (p > 0.05) using one way ANOVA analysis. CONCLUSIONS: Contrast enhanced 4D-CT is advantageous in accurate delineation of tumors and assessing accurate ITV. The treatment plans generated on average 4D-CECT and average d4D-CT have a clinically insignificant effect on dosimetric parameters.

Safety and efficacy of single-fraction gamma knife radiosurgery for benign confined cavernous sinus tumors: our experience and literature review.

Gamma knife radiosurgery (GKRS) has emerged as a suitable primary treatment option for confined cavernous sinus tumors (CSTs) and residual/recurrent benign tumors extending from the surrounding neighborhood. The aim of this review was to further investigate the safety and efficacy of single-fraction GKRS for primary confined CSTs (hemangioma, meningioma, and schwannoma). This was a retrospective analysis of 16 patients of CSTs, primarily treated with GKRS between 2009 and 2017. The patients underwent follow-up clinical and radiological evaluation at a regular interval. Data on clinical and imaging parameters were analyzed. The published literature on GKRS for CSTs was reviewed. There were total 16 patients (eight meningiomas, seven hemangiomas, and one schwannoma). Patients presented with a headache (56.3%), ptosis (50%), and/or restricted extraocular movements (50%). There was 46.6% tumor volume (TV) reduction after single-fraction GKRS. Hemangiomas showed best TV reduction (64% reduction at > 3-year follow-up) followed by schwannoma (41.5%) and meningioma (25.4%). 56.3% of patients developed transient hypoesthesia in trigeminal nerve distribution. 44.4% of patients became completely pain-free. Among cranial nerves, the superior division of the oculomotor nerve showed best outcome (ptosis 62.5%) followed by an improved range of EOM. There was no adverse event in the form of new-onset deficit, vascular complication, or malignant transformation except for one out of the field failures. Among available treatment options, GKRS is the most suitable option by virtue of its minimally invasive nature, optimal long-term tumor control, improvement in cranial neuropathies, cost-effectiveness, favorable risk-benefit ratio, and minimal long-term complications.

Efficiency of a novel non-monotonic segmented leaf sequence delivery of Varian MLC for non-split IMRT fields.

AIM: Development of bidirectional non-monotonic segmented leaf sequence (NSLS) MLC delivery technique compatible with Varian MLC for non-split IMRT fields reducing total monitor units (TotalMU) and the number of segments (NS) simultaneously and assessment of its efficiency using a plan scoring index (PSI). MATERIALS AND METHODS: The optimal fluence of IMRT plans of ten patients of lung carcinoma, calculated using Eclipse TPS version 11.0 (Varian Medical Systems, Palo Alto, CA, USA), was used to generate the segmented MLC fields using our newly developed equally spaced (ES) reducing level and NSLS algorithms in MATLAB® version 2011b for 6-10 intensity levels. These MLC fields were imported into the plans with the same field setup and the final dose was recalculated. The results were compared with those of commercially available multiple static segments (MSS) leaf motion calculation (LMC) algorithm and few previously published algorithms. Plan scoring index (PSI) and degree of modulation (DoM) was calculated to compare the quality of different plans for the same patient. RESULTS: The average differences in TotalMU and NS with respect to MSS algorithm are -3.80% and -14.28% for the NSLS algorithm, respectively. The calculated average PSI and DoM is 0.75, 2.51 and 0.91, 2.41 for the MSS and NSLS algorithms, respectively. CONCLUSIONS: IMRT plans generated using the NSLS algorithm resulted in the best PSI, DoM values among all the leaf sequencing algorithms. Our proposed NSLS algorithm allows bidirectional delivery in Varian medical linear accelerator which is not commercially available. NSLS algorithm is efficient in reducing the TotalMU and NS with equivalent plan quality as that of MSS.

Dosimetric comparison of dynamic conformal arc integrated with segment shape optimization and variable dose rate versus volumetric modulated arc therapy for liver SBRT.

PURPOSE: The aim is a dosimetric comparison of dynamic conformal arc integrated with the segment shape optimization and variable dose rate (DCA_SSO_VDR) versus VMAT for liver SBRT and interaction of various treatment plan quality indices with PTV and degree of modulation (DoM) for both techniques. MATERIAL: Twenty-five patients of liver SBRT treated using the VMAT technique were selected. DCA_SSO_VDR treatment plans were also generated for all patients in Monaco TPS using the same objective constraint template and treatment planning parameters as used for the VMAT technique. For comparison purpose, organs at risk (OARs) doses and treatment plans quality indices, such as maximum dose of PTV (Dmax%), mean dose of PTV (Dmean%), maximum dose at 2 cm in any direction from the PTV (D2cm%), total monitor units (MU's), gradient index R50%, degree of modulation (DoM), conformity index (CI), homogeneity index (HI), and healthy tissue mean dose (HTMD), were compared. RESULTS: Significant dosimetric differences were observed in several OARs doses and lowered in VMAT plans. The D2cm%, R50%, CI, HI and HTMD are dosimetrically inferior in DCA_SSO_VDR plans. The higher DoM results in poor dose gradient and better dose gradient for DCA_SSO_VDR and VMAT treatment plans, respectively. CONCLUSIONS: For liver SBRT, DCA_SSO_VDR treatment plans are neither dosimetrically superior nor better alternative to the VMAT delivery technique. A reduction of 69.75% MU was observed in DCA_SSO_VDR treatment plans. For the large size of PTV and high DoM, DCA_SSO_VDR treatment plans result in poorer quality.

Analysis of volumetric and dosimetric changes in mid treatment CT scan in carcinoma nasopharynx: implications for adaptive radiotherapy.

OBJECTIVE: Carcinoma of nasopharynx is a radiosensitive tumor and therapeutic response during radiation treatment can result in dosimetric variations in the delivered dose to the tumor and critical organs. This study was done to evaluate the volumetric and dosimetric changes seen in tumor tissue and organs at risk in a mid treatment planning scan and its implications for adaptive replanning. Twenty patients of locally advanced carcinoma nasopharynx were evaluated. All patients were started on treatment with a baseline treatment plan on SIB-VMAT. To evaluate volumetric and dosimetric changes during treatment, a mid treatment CT scan (MTS) was taken at the 17th fraction of treatment and compared with the baseline planning CT scan (BS). Adaptive treatment plans were generated on the MTS and further treatment was continued on the adaptive plans. The mean weight loss observed at the 17th fraction of treatment was 3.4 ± 2.6 kg(Mean±S.D). The mean neck diameter at C2 level was 14.19±1.02 and 13.29 ± 1.14 cm in the BS and MTS respectively (p=0.001). The GTV 70 volume showed a 29.16% volume loss. The mean doses received by the right and left parotids were 25.45±0.98 and 24.64±3.8 Gy in the baseline treatment plan and 33.21±11.29 (p=0.054) and 31.76±8.44 Gy respectively in the MTS (p=0.016) The mean weight loss showed a statistically significant correlation with increase in the right parotid(p=0.043) and left parotid doses(p=0.024). Weight loss during treatment combined with volume changes in target tissues mandate routine adaptive replanning while treating carcinoma nasopharynx.

Formulation of normal tissue irradiation volumes in Co-60 and Ir-192 HDR ICBT of Ca cervix using Total Reference Air Kerma (TRAK).

AIM: The aim of this study was to formulate isodose volume relations encompassed by isodose surfaces in Co-60 and Ir-192 HDR intracavitary brachytherapy (ICBT) of cervix carcinoma using the Total Reference Air Kerma (TRAK). BACKGROUND: The TRAK and isodose volumes are radioactive source related. The formulated relations can easily estimate the irradiated isodose volume if the TRAK and dose are known. The C0-60 can also be used for brachytherapy because of its longer half life and comparable OAR doses to Ir-192. MATERIALS AND METHODS: Isodose volumes encompassed by different isodose surfaces and TRAK were obtained from 22 Ca cervix ICBT treatment plans in Co-60 and Ir-192 HDR brachytherapy with 9 Gy prescription to point A. Isodose volume relations were formulated both for Co-60 and Ir-192 brachytherapy source from the slopes and intercepts of the linear fit in the plot between isodose volumes and TRAKs. RESULTS: The TRAK value of Co-60 was higher than Ir-192 by about 7.16%. The isodose volumes at low doses for Co-60 were higher than Ir-192. But no significant differences in the dose to the bladder and rectum were observed due to these sources. For dose to 2 cm3 bladder and rectum volume, the differences were 1.07% and 0.75%, respectively. The correlation coefficient with the 2-tailed significance of correlation (p value) between TPS measured isodose volume and calculated isodose volumes using the formulated relations at different dose values were statistically significant as p < 0.05. CONCLUSION: Results show different isodose volumes for both sources but the dose to the bladder and rectum are nearly the same.

Dose fractionated gamma knife radiosurgery for large arteriovenous malformations on daily or alternate day schedule outside the linear quadratic model: Proof of concept and early results. A substitute to volume fractionation.

BACKGROUND: To evaluate the feasibility, safety and efficacy of dose fractionated gamma knife radiosurgery (DFGKRS) on a daily schedule beyond the linear quadratic (LQ) model, for large volume arteriovenous malformations (AVMs). MATERIAL AND METHODS: Between 2012-16, 14 patients of large AVMs (median volume 26.5 cc) unsuitable for surgery or embolization were treated in 2-3 of DFGKRS sessions. The Leksell G frame was kept in situ during the whole procedure. 86% (n = 12) patients had radiologic evidence of bleed, and 43% (n = 6) had presented with a history of seizures. 57% (n = 8) patients received a daily treatment for 3 days and 43% (n = 6) were on an alternate day (2 fractions) regimen. The marginal dose was split into 2 or 3 fractions of the ideal prescription dose of a single fraction of 23-25 Gy. RESULTS: The median follow up period was 35.6 months (8-57 months). In the three-fraction scheme, the marginal dose ranged from 8.9-11.5 Gy, while in the two-fraction scheme, the marginal dose ranged from 11.3-15 Gy at 50% per fraction. Headache (43%, n = 6) was the most common early postoperative complication, which was controlled with short course steroids. Follow up evaluation of at least three years was achieved in seven patients, who have shown complete nidus obliteration in 43% patients while the obliteration has been in the range of 50-99% in rest of the patients. Overall, there was a 67.8% reduction in the AVM volume at 3 years. Nidus obliteration at 3 years showed a significant rank order correlation with the cumulative prescription dose (p 0.95, P value 0.01), with attainment of near-total (more than 95%) obliteration rates beyond 29 Gy of the cumulative prescription dose. No patient receiving a cumulative prescription dose of less than 31 Gy had any severe adverse reaction. In co-variate adjusted ordinal regression, only the cumulative prescription dose had a significant correlation with common terminology criteria for adverse events (CTCAE) severity (P value 0.04), independent of age, AVM volume, number of fractions and volume of brain receiving atleast 8 Gy of radiation. CONCLUSION: DFGKRS is feasible for large AVMs with a fair nidus obliteration rate and acceptable toxicity. Cumulative prescription dose seems to be the most significant independent predictor for outcome following DFGKRS with 29-30 Gy resulting in a fair nidus obliteration with least adverse events.

Dosimetric correlation of acute and late toxicities in high-risk prostate cancer patients treated with three-dimensional conformal radiotherapy followed by intensity modulated radiotherapy boost.

INTRODUCTION: In prostate cancer, higher radiation doses are often related to higher local control rates. However, the clinical effect of these higher doses on normal tissue toxicities is generally overlooked. We dosimetrically analyze sequential intensity modulated radiotherapy (IMRT) plans in high-risk prostate cancer patients and correlate them with acute and late normal tissue toxicities. MATERIALS AND METHODS: Twenty-five high-risk prostate cancer patients were planned with three-dimensional conformal radiotherapy to a dose of 50 Gy delivered in 25 fractions in 5 weeks, followed by seven-field IMRT boost, to a dose of 24 Gy delivered in 12 fractions in 2.5 weeks, along with hormonal therapy. Acute and late toxicities were analyzed using Radiation Therapy Oncology Group toxicity criteria. Student's t-test was used for correlating doses received by normal tissues with toxicity grade. Five-year disease-free survival (DFS) and biochemical relapse-free survival (RFS) were evaluated using Kaplan-Meier analysis. RESULTS: Median follow-up of patients was 65 months. Of 25 patients, two developed acute Grade 2 rectal toxicity. Only 1 patient developed acute Grade 2 bladder toxicity. Late Grade 2 and 3 rectal toxicity was seen in 2 and 1 patient, respectively. Late Grade 2 and 3 bladder toxicity was seen in 1 patient each. Grade 2 or more acute rectal toxicity correlated significantly with rectal volume receiving >70 Gy (P = 0.04). The 5-year DFS and biochemical RFS was 70.2% and 79.2%, respectively. One patient failed locally and seven failed at distant sites. CONCLUSION: Sequential IMRT with a dose of 74 Gy and maximum androgen blockade is well tolerated in high-risk patients in Indian setup with adequate control rates.

CT and MR image fusion of tandem and ring applicator using rigid registration in intracavitary brachytherapy planning.

The purpose of this study is to find the uncertainties in the reconstruction of MR compatible ring-tandem intracavitary applicators of high-dose rate image-based brachytherapy treatment planning using rigid registration of 3D MR and CT image fusion. Tandem and ring reconstruction in MR image based brachytherapy planning was done using rigid registration of CT and MR applicator geometries. Verifications of registration for applicator fusion were performed in six verification steps at three different sites of tandem ring applicator set. The first site consists of three errors at the level of ring plane in (1) cranio caudal shift (Cranial Shift) of ring plane along tandem axis, (2) antero-posterior shift (AP Shift) perpendicular to tandem axis on the plane containing the tandem, and (3) lateral shift (Lat Shift) perpendicular to the plane containing the tandem at the level of ring plane. The other two sites are the verifications at the tip of tandem and neck of the ring. The verification at the tip of tandem consists of two errors in (1) antero-posterior shift (AP Shift) perpendicular to tandem axis on the plane containing the tandem, and (2) lateral shift (Lat Shift) perpendicular to the plane containing the tandem. The third site of verification at the neck of the ring is the error due to the rotation of ring about tandem axis. The impact of translational errors from -5 mm to 5 mm in the step of 1 mm along x-, y-, and z-axis and three rotational errors about these axes from -19.1° to 19.1° in the step of 3.28° on dose-volume histogram parameters (D(2cc), D(1cc), D(0.1cc), and D(5cc) of bladder, rectum, and sigmoid, and D90 and D98 of HRCTV were also analyzed. Maximum registration errors along cranio-caudal direction was 2.2 mm (1 case), whereas the errors of 31 out of 34 cases of registration were found within 1.5 mm, and those of two cases were less than 2mm but greater than 1.5 mm. Maximum rotational error of ring about tandem axis was 3.15° (1.1 mm). In other direction and different sites of the ring applicator set, the errors were within 1.5 mm. The impacts of registration errors on DVH parameters of bladder, rectum, and sigmoid were very sensitive to antero-posterior shift. Cranio-caudal errors of registration also largely affected the rectum DVH parameters. Largest change of 17.95% per mm and 20.65% per mm in all the DVH parameters of all OARs and HRCTV were observed for ϕ and Ψ rotational errors as compare to other translational and rotational errors. Catheter reconstruction in MR image using rigid registration of applicator geometries of CT and MR images is a feasible technique for MR image-based intracavitary brachytherapy planning. The applicator regis-tration using the contours of tandem and neck of the ring of CT and MR images decreased the rotational error about tandem axis. Verification of CT MR image fusion using applicator registration which consists of six steps of verification at three different sites in ring applicator set can report all the errors due to translation and rotational shift along θ, ϕ, and Ψ. ϕ and Ψ rotational errors, which produced potential changes in DVH parameters, can be tackled using AP Shift and Lat Shift at the tip of tandem. The maximum shift was still found along the tandem axis in this technique.

Cone-beam computed tomography (CBCT) dose optimization technique and image quality assessment scoring.

INTRODUCTION: Linear accelerator (LINAC) embedded with kV source-imager system is capable to do image-guided radiotherapy. The only disadvantage of cone-beam computed tomography image acquisition during treatment is the extra radiation dose to the patient. The aim of this study is to optimize the CBCT imaging doses likely to be received by the patient undergoing radiotherapy without affecting image quality. MATERIAL AND METHODS: The imaging dose to the patient was estimated on CTDI phantoms. The effect of additional filters of different materials (copper, brass, aluminum of thickness 0.1 mm each) was evaluated to find the optimized dose imaging technique. For the pelvis, a single imaging protocol available on the machine was used, whereas for the head and neck region, two protocols, high-quality head and standard-dose head were used. The image quality was assessed on CATPHAN-504 phantom using Owl CATPHAN® QA online tool. A new term "Image Assessment score" (IAS) was introduced to evaluate the image quality. RESULT: In the pelvis protocol, CBCT imaging doses with an additional 0.1-mm brass, copper, and aluminum filter were measured to be reduced by 7.1%, 4.7%, and 2.5%, respectively, whereas for high-quality head protocol, the dose reduction was 25.4% (with brass filter), 22% (with copper filter), and 3.1% (with aluminum filter). For the standard-dose head protocol, doses were reduced by 7.5%, 2.8%, and 2.1% with additional 0.1-mm brass copper and aluminum filters, respectively. Acceptable image quality was observed with all the filters. CONCLUSION: Although the reconstructed images were found somewhat noisier, they did not affect the purpose of imaging, that is, treatment position verification. It was observed that these extra filters further reduce the imaging dose without much affecting the image quality.

Challenges in commissioning the "TSET" technique: A new approach towards monitor unit calculation and beam profile measurements.

INTRODUCTION: Total skin electron beam therapy, commonly known as TSET, is a good choice of treatment for patients suffering from mycosis fungoides. The aim of this study was to introduce a new approach to the beam profile measurement using diodes and to calculate the monitor units required for the TSET treatment by the use of a simple setup of output measurement. Dosimetric measurements required for the treatment were taken to establish the Stanford technique in the department, and the measured data was compared with the published data. MATERIALS AND METHODS: High-energy Linear Accelerator Clinac-DHX, Varian medical system, Palo Alto, CA, was commissioned for TSET. The output of the machine was measured by the use of a Parallel-Plate Chamber (PPC40) as per the TRS 398 recommendation. Diode dosimeters (EDD2 and EDD5) were used for beam profile measurements due to easy setup and to reduce the measurement time. RESULTS: Homogeneous dose distribution within a field size of 80 cm x160 cm was observed with the variation of -5.0% on the horizontal axis and -5.4% on the vertical axis. The calculated monitor unit to deliver 200 cGy per fraction per field at the source to surface (SSD) of 416 cm was 489 MU. CONCLUSION: The technique described for the output measurements is simple and accurate. Results of the absorbed dose and MU measured were within good agreement compared to the published literature.

Modeling of Gamma Index for Prediction of Pretreatment Quality Assurance in Stereotactic Body Radiation Therapy of the Liver.

Purpose: The purpose of this study was to develop a predictive model to evaluate pretreatment patient-specific quality assurance (QA) based on treatment planning parameters for stereotactic body radiation therapy (SBRT) for liver carcinoma. Materials and Methods: We retrospectively selected 180 cases of liver SBRT treated using the volumetric modulated arc therapy technique. Numerous parameters defining the plan complexity were calculated from the DICOM-RP (Radiotherapy Plan) file using an in-house program developed in MATLAB. Patient-specific QA was performed with global gamma evaluation criteria of 2%/2 mm and 3%/3 mm in a relative mode using the Octavius two-dimensional detector array. Various statistical tests and multivariate predictive models were evaluated. Results: The leaf speed (MILS) and planning target volume size showed the highest correlation with the gamma criteria of 2%/2 mm and 3%/3 mm (P < 0.05). Degree of modulation (DoM), MCSSPORT, leaf speed (MILS), and gantry speed (MIGS) were predictors of global gamma pass rate (GPR) for 2%/2 mm (G22), whereas DoM, MCSSPORT, leaf speed (MILS) and robust decision making were predictors of the global GPR criterion of 3%/3 mm (G33). The variance inflation factor values of all predictors were <2, indicating that the data were not associated with each other. For the G22 prediction, the sensitivity and specificity of the model were 75.0% and 75.0%, respectively, whereas, for G33 prediction, the sensitivity and specificity of the model were 74.9% and 85.7%%, respectively. Conclusions: The model was potentially beneficial as an easy alternative to pretreatment QA in predicting the uncertainty in plan deliverability at the planning stage and could help reduce resources in busy clinics.

Sensitivity Response Analysis of Optical Surface Monitoring Systems Using the Fitzpatrick Scale: A Phantom Study.

Purpose: Optical surface monitoring systems (OSMSs) have gained substantial attention in modern radiation therapy, specifically in the context of surface guided radiation therapy, which offers real-time patient surface monitoring, ensuring accurate and effective radiation therapy treatments. The aim of this article is to evaluate the OSMS camera sensitivity toward different skin tones, categorized according to the Fitzpatrick scale, a universal classification of human skin tones, using a phantom. Methods and Materials: This study used Catalyst and Sentinel OSMSs (C-RAD). The Alderson RANDO female pelvis phantom, located at the isocenter in computed tomography simulation and treatment rooms, served as an experimental subject. Eighteen skin tone-matching cotton cloths, selected on the basis of Von Luschan chromatic and Fitzpatrick scales, were wrapped around the phantom for sensitivity evaluation. Camera sensitivity was optimized by adjusting threshold/gain (100%-600%) and integration time during individual scans in both rooms. Temporal response analysis spanned 2 months, with 16 measurements for each OSMS taken in varying light conditions. Results: The OSMSs successfully detected the surface of cloth-covered phantoms with varying mean (SD) integration times: 550 (34) to 950 (43) µs for the Sentinel system and 2300 (71) to 12,000 (400) µs for the Catalyst system. The sensitivity parameters differed for each skin tone, with lighter skin requiring shorter integration times and gain/threshold values. Darker skin tones necessitated higher parameters for optimal surface images. The reliability of the systems declined with excessive parameters, leading to noise and compromised accuracy in patient positioning. Conclusions: Optimized sensitivity parameters tailored to individual skin tones are crucial for effective real-time patient surface monitoring in radiation therapy, as variations in skin color can affect the accuracy of measurements. The precision of skin color measurements in OSMSs relies on carefully adjusting camera sensitivity parameters. However, careful consideration is essential, as larger values are required for darker skin tones, compromising reliability. This suggests the need for exploring alternative image guidance methods for patients with darker skin tones.

Pilot Evaluation of Perioperative High Dose Rate Brachytherapy in Head Neck Cancers.

Perioperative high dose rate brachytherapy involves insertion of brachytherapy catheter over the tumor bed during surgical removal of disease followed by radiation in the postoperative period. It has applications in radiotherapy dose escalation or reirradiation and for extending the surgical margins. We report here initial results of treatment in five cases of locally advanced head and neck cancers.

Preliminary results of hypofractionated radiotherapy in breast cancer in Chandigarh, India: single-centre, non-inferiority, open-label, randomised, phase 3 trial.

Background: Globally, most of the randomised trials with hypofractionation in patients with breast cancer have used 3-dimensional conformal radiotherapy technique (3D-CRT). As facilities for 3D-CRT technique may not be available in low-resource settings, there is a need to see if hypofractionation is feasible and safe with 2-dimensional (2-D) technique. In this study, we compared a 3-week radiation schedule with a 2-week schedule of hypofractionated radiotherapy in patients with breast cancer with 2-D technique. Methods: The current study was an open-label, randomised, phase 3 trial. Patients with breast cancer, stage I-III, post mastectomy or after breast conservative surgery who needed adjuvant locoregional radiotherapy were randomised in the Department of Radiotherapy & Oncology, Post Graduate Institute of Medical Education & Research (PGIMER), Chandigarh, India; to 34Gy in 10 fractions over 2 weeks (2-week arm) or 35Gy in 15 fractions over 3 weeks to the chest wall and 40Gy/15#/3wks to breast and supraclavicular fossa (3-week arm). Boost dose when indicated was 8-10Gy/2-4#/2-4 days in both the arms. Patients were planned on a 2-dimensional (2D) simulator with 2 tangential fields to breast/chest wall and incident supraclavicular fossa field. Acute toxicity was assessed using the Radiation Therapy Oncology Group (RTOG) grading scale. Assessments were carried out weekly during radiotherapy and at 4 weeks after treatment by the physician. Cosmetic outcome was assessed using the Harvard/National Surgical Adjuvant Breast and Bowel Project (NSABP)/RTOG scale. The toxicity rates between the two arms were compared using Fisher's exact tests. The trial was approved by institutional ethics committee and registered with ClinicalTrials.gov, number NCT04075058. Findings: This study included 1121 eligible patients from June 2015 to December 2020. Median follow-up was 35 months (6-84 months). Mean age was 48 years (24-75 years). The patient characteristics were comparable between the two arms except for more mastectomies in the 3-week arm and more node-positive patients in the 2-week arm. There were more oestrogen receptor-positive tumors in the 3-week arm. Acute skin toxicities were comparable between the two arms. Grade 2 and 3 skin toxicity was 100 (18%) and 82 (15%); and 16 (3%) and 12 (2%) in the 3-week and 2-week arm (p = 0.21), respectively. Cosmetic outcome was assessed as Excellent or Good for 89% of patients in the 3-week arm as compared to 94% in the 2-week arm (p = 0.004). Interpretation: The two radiation schedules were comparable in terms of acute skin toxicity. The cosmetic outcome was better with the 2-week schedule. The preliminary findings indicate 2-week radiotherapy schedule with 2-D technique was better than the 3-week schedule in patients with breast cancer. However, disease outcomes and late-term toxicities need to be further checked. Funding: This study was funded by Science and Engineering Research Board (SERB), India.

Simultaneous Integrated Boost (SIB) Versus Sequential Boost in Anal Cancer Patients: A Single-Center Experience.

PURPOSE: Concurrent chemoradiation is the standard of care for the treatment of anal cancer. Radiation can be delivered by sequential or simultaneous integrated boost (SIB) approach. The present study was conducted to compare the treatment outcomes and toxicity profile of patients with anal cancer treated with sequential boost and SIB approach. METHODS: A single-institution retrospective analysis of patients with squamous cell carcinoma of the anal canal treated between 2019 and 2022 with radical chemoradiation was performed. The sequential boost schedule consisted of 45 Gy in 25 fractions (1.8 Gy daily) to the gross tumor, nodes, and elective nodal volume, followed by a 9 Gy in five fractions boost to the gross disease. Patients receiving SIB were treated as per RTOG 0529 protocol. In both the groups, patients were treated with volumetric modulated arc therapy (VMAT). The two groups were compared in terms of overall survival (OS), colostomy-free survival (CFS), relapse-free survival (RFS), and acute toxicity profile. p-values < 0.05 were considered statistically significant. RESULTS: The patient and disease characteristics in both treatment arms were comparable. The only difference was a significantly longer overall treatment time of ≥ 50 days in the sequential arm (77.8% vs 43.8%, p = 0.04). The median follow-up was 18 months. The 2-year CFS was 80% in sequential vs 87.5% at 2 years for the SIB arm, 2-year OS 83.3% vs 58.6%, and 2-year RFS was 38.9% vs 41.7%, respectively. A total of 14 (77.8%) in sequential and 8 (50%) in the SIB arm had disease relapse. On univariate analysis, the involved pelvic lymph node significantly affected OS (HR 10.45, p = 0.03) while inguinal lymph node involvement adversely affected RFS (HR 6.16, p = 0.02). The most common acute toxicity was radiation-induced dermatitis, 15 (83.4%; 5 grade II, 10 grade III) in sequential vs 7 (43.8%; 3 each grade II and III) in the SIB group followed by hematological (61.1% vs 68.75%). However, the incidence of overall acute toxicities was significantly less in the SIB arm (p = 0.006). CONCLUSION: Our study showed that concurrent chemoradiation with the SIB-VMAT approach is well tolerated in patients of anal carcinoma and resulted in lesser treatment interruptions and comparable outcomes as compared to the sequential approach. Our results warrant further evaluation in a prospective study.

Dosimetric comparison of doses to organs at risk using 3-D conformal radiotherapy versus intensity modulated radiotherapy in postoperative radiotherapy of periampullary cancers: implications for radiation dose escalation.

CONTEXT: Postoperative periampullary cancers with high risk features are managed with adjuvant chemo radiotherapy. Doses of 40-50 Gy have generally been used in conventional radiotherapy. Dose escalation with conventional radiotherapy has been restricted due to surrounding critical organs. OBJECTIVE: The objective of this dosimetric analysis was to evaluate the dose of radiation received by organs at risk using 3D conformal radiotherapy (3DCRT) and intensity modulated radiotherapy (IMRT). METHODS: Ten postoperative patients of periampullary cancers were selected for this dosimetric analysis. Planning CT scans films were taken with slice thickness of 2.5 mm and transferred to Eclipse treatment planning system. The clinical target volume (CTV) included the postoperative tumor bed and draining lymph nodal areas. A 1 cm margin was taken around the CTV to generate the planning target volume (PTV). Critical structures contoured for evaluation included bowel bag, bilateral kidneys, liver, stomach and spinal cord. IMRT plans were generated using seven field coplanar beams and 3DCRT planning was done using one anterior and two lateral fields. A dose of 45 Gy in 25 fractions was prescribed to the PTV. RESULTS: V45 for bowel bag was 212.3 ± 159.0 cc (mean volume ± standard deviation) versus 80.9 ± 57.4 cc in 3DCRT versus IMRT (P=0.033). The V28 dose analysis for bilateral kidneys showed a value of 32.7±23.5 cc (mean volume ± standard deviation) versus 7.9 ± 7.4 cc for 3DCRT versus IMRT, respectively (P=0.013). The D60 for liver using 3DCRT and IMRT was 28.4 ± 8.6 Gy (mean dose ± standard deviation) and 19.9 ± 3.2 Gy, respectively (P=0.020). CONCLUSIONS: Doses to bowel bag, liver and kidneys was significantly reduced using IMRT leaving ample scope for dose escalation.

A calibration method for patient specific IMRT QA using a single therapy verification film.

AIM: The aim of the present study is to develop and verify the single film calibration procedure used in intensity-modulated radiation therapy (IMRT) quality assurance. BACKGROUND: Radiographic films have been regularly used in routine commissioning of treatment modalities and verification of treatment planning system (TPS). The radiation dosimetery based on radiographic films has ability to give absolute two-dimension dose distribution and prefer for the IMRT quality assurance. However, the single therapy verification film gives a quick and significant reliable method for IMRT verification. MATERIALS AND METHODS: A single extended dose rate (EDR 2) film was used to generate the sensitometric curve of film optical density and radiation dose. EDR 2 film was exposed with nine 6 cm × 6 cm fields of 6 MV photon beam obtained from a medical linear accelerator at 5-cm depth in solid water phantom. The nine regions of single film were exposed with radiation doses raging from 10 to 362 cGy. The actual dose measurements inside the field regions were performed using 0.6 cm(3) ionization chamber. The exposed film was processed after irradiation using a VIDAR film scanner and the value of optical density was noted for each region. Ten IMRT plans of head and neck carcinoma were used for verification using a dynamic IMRT technique, and evaluated using the gamma index method with TPS calculated dose distribution. RESULTS: Sensitometric curve has been generated using a single film exposed at nine field region to check quantitative dose verifications of IMRT treatments. The radiation scattered factor was observed to decrease exponentially with the increase in the distance from the centre of each field region. The IMRT plans based on calibration curve were verified using the gamma index method and found to be within acceptable criteria. CONCLUSION: The single film method proved to be superior to the traditional calibration method and produce fast daily film calibration for highly accurate IMRT verification.