Retrospective study on performance of constancy check device in Linac beam monitoring using Statistical Process Control.

AIM: To examine the application of Statistical Process Control (SPC) and Ishikawa diagrams for retrospective evaluation of machine Quality Assurance (QA) performance in radiotherapy. BACKGROUND: SPC is a popular method for supplementing the performance of QA techniques in healthcare. This work investigates the applicability of SPC techniques and Ishikawa charts in machine QA. MATERIALS AND METHODS: SPC has been applied to recommend QA limits on the particular beam parameters using the QUICKCHECK webline QA portable constancy check device for 6 MV and 10 MV flattened photon beams from the Elekta Versa HD linear accelerator (Linac). Four machine QA parameters - beam flatness, beam symmetry along gun target direction and left-right direction, and beam quality factor (BQF) - were selected for retrospective analysis. Shewhart charts, Exponentially Weighted Moving Average (EWMA) charts and Cumulative Sum (CUSUM) charts were obtained for each parameter. The root causes for a failure in machine QA were broken down into an Ishikawa diagram enabling the user to identify the root cause of error and rectify the problem subsequently. RESULTS: Shewhart charts and EWMA charts applied could detect loss in control in one variable in the 6 MV beams and in all four variables in 10 MV beams. CUSUM charts detected offsets in the readings. The Ishikawa chart exhaustively included the possible errors that lead to loss of control. CONCLUSION: SPC is proven to be effective for detection of loss in control in machine QA. The Ishikawa chart provides the set of probable root causes of machine error useful while troubleshooting.

Validation of a simple technique for accurate treatment delivery for bilateral breast irradiation using the electronic portal imaging device.

Background and Aims: While bilateral breast cancer is rare, the challenge for the radiation oncologist is to limit the dose to multiple important organs-at-risk and reducing the chance of overlapping tangential fields to limit hotspots. In this study, we present a simple technique to verify the setup accuracy of breast tangential fields using the electronic portal imaging device (EPID) for bilateral breast cancer. Patients and Methods: A 74-year-old female, with bilateral breast cancers, right staged as T1N0M0 and the left T2N1M0, received postoperative radiotherapy following bilateral breast conservative surgery. Standard CT-based simulation and target delineation were done, followed by treatment planning using classical field arrangements with two separate isocenters, one for each breast (keeping identical anteroposterior and superior-inferior coordinates). The planned doses were 45 Gy/25 # for whole breasts, plus tumor bed boost of 15 Gy/6 # and 50 Gy/25 # to left supraclavicular fossa. After setting up the patient, two small lead wires were placed at the medial borders of medial tangents (as seen on light fields) of each breast (longer one for left), followed by EPID imaging (dual exposure: One lateral tangent field image and other larger to include lead wires) of respective contralateral lateral tangential fields to verify that there was no actual overlapping with the opposite medial tangential field, as indicated by the lead wires. Conclusion: The study has validated a simple EPID-based technique for routine use in the field matching for radiotherapy of bilateral breast cancer.

Choosing a career in radiation oncology in India: A survey among young radiation oncologists.

BACKGROUND: Radiation oncology in India is much debated as a career option to take up. This survey among young radiation oncologists (YROs), the first of its kind, attempts to assess the career expectations and concerns that affect most of us. MATERIALS AND METHODS: This survey was conducted using the online survey tool of SurveyMonkey in October 2018. The Association of Radiation Oncologists of India (AROI) members' database was used to send the survey link over E-mail to recipients (AROI life member after 2004). RESULTS: Out of 1685 invitees, 492 (29.19%) recipients took the survey. Most (69.14%) of the respondents were males who worked as senior residents and junior consultants and employed in private hospitals and state-level teaching institutes. Postspecialization (MD/DNB) experience was mostly <3 years (56.52%). Most of YROs worked in Tier-I city (48.9%) mostly in telecobalt-based facilities. Most of our respondents (73.01%) aspired to work in academic teaching hospital/research institute, and the primary concern was academics/research (39.88%) followed by income (23.31%). There was a similar distribution of respondents with respect to their desire to shift to medical oncology. There was marked dissatisfaction over remuneration, job openings, job security, and poor scope of career improvement. 56.50% of respondents believed that they need to move abroad to improve their quality of life. However, 76.69% of respondents still felt very passionate about their professional choice. Finally, 61.97% of professionals believed that this survey will correctly reflect the present scenario among YROs. CONCLUSIONS: The survey portrays a mixed picture as expected. Major policy changes are required to improve the infrastructure and job opportunities of this profession.

Clinical audit of dose-escalated radical radiotherapy for advanced cervical carcinoma using a pragmatic protocol (3 fractions of 8 Gy HDR brachytherapy).

INTRODUCTION: Recent image-guided brachytherapy data suggests, dose-escalation to a cumulative EQD2 (equivalent dose delivered at 2 Gy/#) of ≥87 Gy is associated with significantly better disease control. We present a clinical audit of a pragmatic radical radiotherapy protocol for advanced cervical cancer, using fewer fractions of brachytherapy than in the presently most popular protocol. MATERIAL & METHODS: Between July 2015 and December 2018, 96 consecutive advanced cervical carcinoma patients were treated by pelvic external beam radiotherapy (EBRT) (50 Gy/25fractions/5 weeks) ± weekly intravenous chemotherapy followed by image guided high dose rate (HDR) brachytherapy, using intracavitary/interstitial/hybrid techniques (intended point A dose: 8 Gy/fractions) × 3 fractions (cumulative target EQD2 ≥ 86 Gy). Insertion was done individually for each fraction of treatment. RESULTS: All patients completed their intended radiation protocol. 93.8% patients achieved complete response, while 6.2% patients achieved only partial response; no patients had stable/progressive disease. Out of the patients with partial response, 4.2% (4 out of 5 cases) cases of central/nodal residual disease underwent salvage surgery. At a median follow up of 21 months, 8.3% (8) patients had local failure, 1.1% (1) had nodal failure and 3.1% (3) had distant failures. Median Failure Free Survival was 29 months (26.5-31.5 months). On follow up, 6.3% and 3.2% patients had grade 2 or worse rectal and bladder morbidities respectively. CONCLUSION: The protocol under study has been safe and effective in achieving dose-escalated radical chemoradiation in advanced cervical carcinoma. The use of fewer insertions of brachytherapy is logistically easier & can also be expected to improve compliance.

Comparative performance analysis of 2D and 3D gamma metrics for patient specific QA in VMAT using Octavius 4D with 2D-Array 1500.

INTRODUCTION: Gamma pass percentage (GPP) is the predominant metric used for Patient Specific Quality Assurance (PSQA) in radiation therapy. The dimensionality of the measurement geometry in PSQA has evolved from 2D planar to 3D planar, and presently to state-of-the-art 3D volumetric geometry. We aim to critically examine the performance of the three-dimensional gammas vis-à-vis the older gamma metrics of lower dimensionality to determine their mutual fungibility in PSQA, using clinically approved Volumetric Arc Therapy (VMAT) plans. METHODS AND MATERIALS: Gamma pass percentages derived from PSQA for VMAT plans using Octavius 4D phantom with 2D-Array 1500 and its proprietary software were recorded. 2D planar, 3D planar, and 3D volumetric gamma pass percentages were retrospectively extracted for multiple treatment plans at three sites, using three acceptance limits, and for two modes of normalization. The differences in mean pass percentages, and the pairwise correlation between geometries were calculated within limits of statistical significance. RESULTS: A significant increase in mean pass rates was observed from 2D planar to 3D planar geometries. The difference was less pronounced from 3D planar to 3D volumetric. 2D planar v/s 3D planar showed a significant degree of correlation among themselves, which was not seen against most of the 3D volumetric pass rates. CONCLUSION: The mean gamma pass rates show conclusive evidence of the benefits of shifting from 2D planar to higher dimensions measurement geometries, but the benefits of using 3D volumetric compared to 3D planar is not always unequivocal. The correlations show mixed results regarding the interdependence of pass percentages at different geometries.

Dosimetric analysis of Deep Inspiratory Breath-hold technique (DIBH) in left-sided breast cancer radiotherapy and evaluation of pre-treatment predictors of cardiac doses for guiding patient selection for DIBH.

INTRODUCTION: The risk of radiotherapy-associated cardiovascular disease has been a concern for decades in breast cancer survivors. The objective of our study is to evaluate the dosimetric benefit of Deep Inspiratory Breath-hold technique (DIBH) on organs-at-risk (OAR) sparing in left-sided breast cancer radiotherapy and to find out pre-treatment predictors of cardiac doses for guiding patient selection for DIBH. MATERIAL AND METHODS: Pre-radiotherapy planning CT scans were done in Free Breathing (FB) and in DIBH [using Active Breathing Coordinator system (ABC™)] in 31 left sided breast cancer patients. 3DCRT plans were generated for both scans. Comparison of anatomical and dosimetric variables were done using paired t test and correlation was evaluated using Pearson correlation. Linear regression was used to get independent predictors of cardiac sparing and Receiver Operating Characteristic (ROC) curve analysis was done to find out the specific threshold of the predictors. RESULTS: There was a 39.15% reduction in mean heart dose in DIBH compared to FB (2.4 Gy vs 4.01 Gy) (p < 0.001), 19% reduction in maximum Left Anterior Descending (LAD) dose and a 9.9% reduction in ipsilateral lung mean dose (p = 0.036) with DIBH. A significant correlation was observed between reduction in Heart Volume in Field (HVIF) and Maximum Heart Depth (MHD) with reduction in mean heart dose. Reduction in HVIF (ΔHVIF) independently predicted cardiac sparing. CONCLUSION: DIBH leads to significant reduction in OAR doses and is suggested for all patients of left-sided breast cancer undergoing radiotherapy. However, HVIF and MHD predicted for cardiac sparing and threshold criteria of ΔHVIF and ΔMHD may be used by centres with high workload to select patients for DIBH.

Outcomes of high dose rate interstitial boost brachytherapy after external beam radiation therapy in head and neck cancer--an Indian (single institutional) learning experience.

PURPOSE: This study is to assess efficacy and toxicity associated with external beam radiation therapy (EBRT) and high dose rate (HDR) interstitial Iridium-192 ((192)Ir) brachytherapy for the treatment of squamous carcinoma of the oropharynx and oral cavity. METHODS AND MATERIALS: Between July 2004 and June 2006, 33 patients with oropharynx and oral cavity carcinomas were treated with (192)Ir interstitial implants after EBRT at Medical College Hospital, Kolkata. Fifteen patients had early stage disease (Stage I and II) and 18 had advanced stage disease (Stage III and IV). All received EBRT to a median dose of 50Gy (range, 46-66Gy) to the primary tumor and regional lymph nodes before brachytherapy. Node-positive patients with residual neck disease also underwent neck dissection. Brachytherapy dose (HDR) in combination with EBRT varied from 14 to 21Gy, 3-3.5Gy per fraction, two fractions daily. Locoregional control, freedom from disease, and complications were assessed. RESULTS: Followup duration was between 18 and 40 months. At the end of treatment with radiation, 79% achieved complete response (CR) (p<0.009), 21% achieved partial response (PR) and the ultimate control rate (including surgical salvage) was 100% and 78% for early and advanced disease, respectively (p<0.108). Three (9%) patients failed locally after CR. No distant metastasis was seen during followup. Grade 3 mucositis was seen in 12% cases. Transient hemorrhage occurred in 3 (9%) patients and local infection in 1 (3%) patient. Severe dysphagia was seen in 1 (3%) patient. 5/33 (15%) patients experienced xerostomia (Grade 3-4), but almost all patients had Grade 1-2 xerostomia. CONCLUSION: Oropharyngeal and oral cavity tumors can be effectively treated with (192)Ir implant boost after EBRT. Local control is excellent and complication rates are acceptable.

Living with the Elekta Compact: Limitations and ways around them.

Elekta AB, Sweden has recently propagated the Elekta Compact--a low-cost, small-footprint, single energy (6MV), linear accelerator, in India. The absence of electron beams and the inability to seamlessly deliver inverse planned intensity modulated radiotherapy (IMRT) segments, mean that some out-of-the-box thinking is mandatory for the full range of required treatments in different clinical settings, but is ultimately very rewarding. Our department started off in July 2011, with the Elekta Compact, equipped with MLCi2 and a camera-based electron portal imaging device. For head-neck cancers, we have successfully utilized a 3D conformal class-solution of eight-to-nine oblique beams, with multiple segments, to deliver an adequate dose to the posterior neck, respecting spinal cord tolerance. Parotid gland sparing is possible in selected node-negative hypopharyngeal/laryngeal cancers. For prostate cancers, we have developed a forward-planned IMRT protocol to routinely deliver 76-80 Gy to the prostate, with margins, while conforming to the same rectal dose-volume constraints as in inverse IMRT. Response and tolerance have been excellent so far. In head-neck cancers, the majority (71%) of patients was locally advanced; however, complete response was achieved in 75% of the cases. Grade 3 acute toxicities were seen in only 7% of the cases and compliance overall was excellent, with no patients requiring a gap in treatment. We achieved biochemical control in 100% of the prostate cancer patients; no patients had grade 3 acute toxicities, and with a median follow-up of 12 months, have yet to see any late rectal bleeding. Although engineered for simplicity and versatility, the Compact requires some innovative thinking by clinicians/physicists to optimize the full range of its possibilities. However, upgrades like inverse IMRT delivery, which are in the pipeline, are urgently needed for it to be viable, especially in a single-accelerator department.

Dosimetric comparison between conventional and conformal radiotherapy for carcinoma cervix: Are we treating the right volumes?

BACKGROUND AND PURPOSE: Conventional portals, based on bony anatomy, for external beam radiotherapy for cervical cancer have been repeatedly demonstrated as inadequate. Conversely, with image-based conformal radiotherapy, better target coverage may be offset by the greater toxicities and poorer compliance associated with treating larger volumes. This study was meant to dosimetrically compare conformal and conventional radiotherapy. MATERIALS AND METHODS: Five patients of carcinoma cervix underwent planning CT scan with IV contrast and targets, and organs at risk (OAR) were contoured. Two sets of plans-conventional and conformal were generated for each patient. Field sizes were recorded, and dose volume histograms of both sets of plans were generated and compared on the basis of target coverage and OAR sparing. RESULTS: Target coverage was significantly improved with conformal plans though field sizes required were significantly larger. On the other hand, dose homogeneity was not significantly improved. Doses to the OARs (rectum, urinary bladder, and small bowel) were not significantly different across the 2 arms. CONCLUSION: Three-dimensional conformal radiotherapy gives significantly better target coverage, which may translate into better local control and survival. On the other hand, it also requires significantly larger field sizes though doses to the OARs are not significantly increased.

Effect of bladder distension on dosimetry of organs at risk in computer tomography based planning of high-dose-rate intracavitary brachytherapy for cervical cancer.

PURPOSE: Distension and shape of urinary bladder may vary during intracavitary brachytherapy (ICBT) for cervical cancer, significantly affecting doses to bladder, rectum, sigmoid colon and small intestine and consequently late radiation toxicities. This study is to evaluate the effects of different fixed volume bladder distention on dosimetry, assessed by three dimensional image based planning, in different organs at risk during the treatment of cervical cancer with ICBT. MATERIAL AND METHODS: Forty seven cervical cancer patients (stage IB to IVA) were qualified for ICBT following external beam radiotherapy. Urinary bladder was distended with different volumes of normal saline instilled by a Foley's catheter. Planning CT scans were performed after insertion of applicators and three dimensional treatment planning was done on Brachyvision(®) treatment planning system (Varian Medical Systems, Palo Alto, CA). Dose volume histograms were analyzed. Bladder, rectum, sigmoid colon and small intestine doses were collected for individual plans and compared, based on the amount of bladder filling. RESULTS: Mean dose to the bladder significantly decreased with increased bladder filling. However, doses to the small volumes (0.1 cc, 1 cc, 2 cc) which are relevant for brachytherapy, did not change significantly with bladder filling for bladder, rectum or sigmoid colon. Nevertheless, all dose values of small intestine are decreased significantly with bladder filling. CONCLUSIONS: Bladder distension has no significant effect on doses received during brachytherapy by relevant volumes of bladder, rectum and sigmoid colon except intestine where values are decreased with bladder distension. A larger study with clinical correlation of late toxicities is essential for proper evaluation of this strategy.

AIDS: a radiation oncologist's perspective.

While HIV is often associated with tuberculosis and a number of opportunistic infections, the spectrum of diseases of patients with HIV infection encompasses a number of malignancies as well. Typically, these are the AIDS-defining malignancies, though other malignancies also comprise a significant caseload. Radiotherapy plays an integral part in anti-cancer treatment and its tolerance and efficacy in HIV+ patients are therefore important. The patient's level of immunity as manifested by the CD4 count has a significant bearing on treatment outcomes. In some cases, like primary central nervous system lymphoma (PCNSL), the occurrence of the malignancy itself is tied to the patient's immunity with increased incidence in patients with CD4 counts less than 50/mm 3. The success of highly active antiretroviral therapy (HAART) has allowed administration of standard doses of radiotherapy and even chemotherapy in recent times leading to improved outcomes. In general, standard radiotherapy and concomitant chemo-radiotherapy protocols should be used wherever possible, so as not to compromise disease control. Local control and disease-specific survival rates in HIV patients are no worse than in HIV? patients, but this is only true for CD4 counts above 200/mm 3. In certain situations like cervical intraepithelial neoplasia CIN, HAART itself is associated with disease regression. The question of increased radiosensitivity in HIV patients remains unresolved in most diseases and there are sparse data with regard to non-HIV associated malignancies in these patients. Greater caution and emphasis on good supportive care and HAART would appear to be essential when treating the malignancies in HIV+ patients with standard anti-cancer regimens.

Optimized point dose measurement for monitor unit verification in intensity modulated radiation therapy using 6 MV photons by three different methodologies with different detector-phantom combinations: A comparative study.

The study was aimed to compare accuracy of monitor unit verification in intensity modulated radiation therapy (IMRT) using 6 MV photons by three different methodologies with different detector phantom combinations. Sixty patients were randomly chosen. Zero degree couch and gantry angle plans were generated in a plastic universal IMRT verification phantom and 30×30×30 cc water phantom and measured using 0.125 cc and 0.6 cc chambers, respectively. Actual gantry and couch angle plans were also measured in water phantom using 0.6 cc chamber. A suitable point of measurement was chosen from the beam profile for each field. When the zero-degree gantry, couch angle plans and actual gantry, couch angle plans were measured by 0.6 cc chamber in water phantom, the percentage mean difference (MD) was 1.35%, 2.94 % and Standard Deviation (SD) was 2.99%, 5.22%, respectively. The plastic phantom measurements with 0.125 cc chamber Semiflex ionisation chamber (SIC) showed an MD=4.21% and SD=2.73 %, but when corrected for chamber-medium response, they showed an improvement, with MD=3.38 % and SD=2.59 %. It was found that measurements with water phantom and 0.6cc chamber at gantry angle zero degree showed better conformity than other measurements of medium-detector combinations. Correction in plastic phantom measurement improved the result only marginally, and actual gantry angle measurement in a flat- water phantom showed higher deviation.

Intestinal mantle cell lymphoma recurring at laparotomy scar region.

Mantle cell lymphoma (MCL) is a moderately aggressive variety of non-Hodgkins lymphoma. Extranodal presentation of MCL is well known, the intestine being a common site. The incidence of colorectal involvement is relatively rare. Moreover, the recurrence of the disease at laparotomy scar site is even more rare. We report an unusual case of incision line recurrence in a case of colonic MCL occuring three years after initial treatment.