VicTAG chemotherapy audit toolkit: Improving chemotherapy quality and safety.

OBJECTIVE: Off-protocol prescribing of systemic anti-cancer therapy (SACT) can lead to concerns about effectiveness of patient care. To identify variations in practice, a toolkit was developed for health services to address patient safety and the risk of sub-optimal outcomes for patients. DATA SOURCES: Following significant incidents with SACT in South Australia and New South Wales, the Department of Health and Human Services, Victoria (the department) conducted an assessment of Victorian public health services to understand current practice regarding SACT protocol governance. A literature review examining SACT auditing was also undertaken to guide improvements. A department supported Chemotherapy Audit Toolkit (CAT) was created for implementation at public hospitals in Victoria. A post-implementation survey was done on uptake and issue identification. DATA SUMMARY: An initial assessment showed that 27% of Victorian public health services were undertaking retrospective review of SACT dosing, which was targeted for improvement. The literature review identified little guidance, however an audit of current sector practices found several audit methodologies. A process that involved audits by health services assessing their own practice was adopted. The toolkit was developed and piloted with health services. A post-implementation survey showed that 20% of services were using the toolkit, 35% were implementing the toolkit and 45% did not use the toolkit. CONCLUSIONS: The VicTAG CAT has been adopted by more than half of Victorian public health services and is being used to influence prescribing. Implementation of the toolkit has been affected by resource reallocation due to the COVID-19 pandemic. The CAT is available online.

Disparities in radiation therapy utilization for cancer patients in Victoria.

INTRODUCTION: To evaluate the proportion of cancer patients who received radiation therapy (RT) within 12 months of cancer diagnosis (RTU12) and identify factors associated with RTU12. METHODS: This is a population-based cohort of individuals with incident cancer, diagnosed between 2013 and 2017 in Victoria. Data linkages were performed between the Victorian Cancer Registry and Victorian Radiotherapy Minimum Dataset. The primary outcome was the proportion of patients who had RTU12. For the three most common cancers (i.e., prostate, breast and lung cancer), the time trend in RTU12 and factors associated with RTU12 were evaluated. RESULTS: The overall RTU12 in our study cohort was 26-20% radical RT and 6% palliative RT. Of the 21,735 men with prostate cancer, RTU12 was 17%, with no significant change over time (P-trend = 0.53). In multivariate analyses, increasing age and lower socioeconomic status were independently associated with higher RTU12 for prostate cancer. Of the 20,883 women with breast cancer, RTU12 was 64%, which increased from 62% in 2013 to 65% in 2017 (P-trend < 0.05). In multivariate analyses, age, socioeconomic status and area of residency were independently associated with RTU12 for breast cancer. Of the 13,093 patients with lung cancer, RTU12 was 42%, with no significant change over time (P-trend = 0.16). In multivariate analyses, younger age, male and lower socioeconomic status were independently associated with higher RTU12. CONCLUSION: In this large population-based state-wide cohort of cancer patients, only 1 in 4 had RT within 12 months of diagnosis. There were marked sociodemographic disparities in RTU12 for prostate, breast and lung cancer patients.

Patterns of the use of advanced radiation therapy techniques for the management of bone metastases and the associated factors in Victoria.

INTRODUCTION: To describe the pattern of the use of advanced radiation therapy (RT) techniques, including intensity-modulated RT (IMRT), volumetric modulated arc therapy (VMAT), and stereotactic body RT (SBRT) for the management of bone metastases (BM), and the associated factors in Victoria. METHODS: We used a population-based cohort of patients from the state-wide Victorian Radiotherapy Minimum Data Set (VRMDS) who received RT for BM between 2012 and 2017. The primary outcome was proportion of RT courses using advanced RT techniques. The Cochran-Armitage test for trend was used to evaluate temporal trend in advanced RT use. Multinomial logistic regression was used to identify factors associated with advanced RT use. RESULTS: A total of 18,158 courses of RT were delivered to 10,956 patients-16,626 (91.6%) courses were 3D conformal RT, 857 (4.7%) IMRT/VMAT and 675 (3.7%) SBRT. There was a sharp increase in IMRT/VMAT use from <1% in 2012-2015, to 10.1% in 2016 and 16.3% in 2017 (P-trend < 0.001). Increase in SBRT use was more gradual, from 1.2% in 2012 to 4.8% in 2016 and 5.5% in 2017 for SBRT (P-trend<0.001). In multivariate analyses, year of RT was the strongest predictor of IMRT/VMAT use (OR = 41; 95%CI = 25-67; P < 0.001, comparing 2012-2013 and 2016-2017). Primary tumour type (prostate cancer) was the strongest predictor of SBRT use (OR = 6.07; 95% CI = 4.19-8.80; P < 0.001). CONCLUSION: Overall, there was increasing trend in the use of advanced RT techniques for BM in Victoria, with a distinct pattern for IMRT/VMAT compared with SBRT - SBRT uptake was more gradual while IMRT/VMAT uptake was abrupt, occurring contemporaneously with Medicare Benefit Scheme funding changes in 2016.

Increasing use of post-mastectomy hypofractionated radiation therapy for breast cancer in Victoria.

INTRODUCTION: The aim of this study was to evaluate the use of post-mastectomy hypofractionationed radiation therapy (HFRT) for breast cancer in Victoria, Australia. METHODS: This is a population-based cohort of women with breast cancer who received post-mastectomy RT to the chest wall with or without nodal irradiation between 2012 and 2017. HFRT was defined as <25 fractions of RT. Data were captured in the Victorian Radiotherapy Minimum Dataset (VRMDS). The changing pattern of HFRT use was evaluated using the Cochran-Armitage test. Patient-, treatment- and institutional-related factors associated with HFRT use were evaluated using multivariable logistic regression. RESULTS: Two thousand and twenty-one women were included in this study, of which 238 (12%) received HFRT. This increased from 8% in 2012 to 18% in 2017 (P-trend < 0.001). Older women were more likely to have HFRT (26% in women above 70 years vs 6% in women under 50 years; P < 0.001). Women who did not have nodal irradiation were more likely to have HFRT than those who did (18% vs 9% respectively; P < 0.001). In multivariate analyses, the progressive increase in HFRT use over time remained statistically significant - women treated in 2017 were four times more likely to receive HFRT than those treated in 2012 (95% CI = 2.1-7.7; P < 0.001). Other factors independently associated with increased likelihood of HFRT use included increasing age at RT, and lack of nodal irradiation. CONCLUSION: In this first Australian study evaluating the use of post-mastectomy HFRT, we observed increasing HFRT use in Victoria over time. We anticipate this rising trend will continue in the coming years.

Differences in treatment choices for localised prostate cancer diagnosed in private and public health services.

OBJECTIVE: To compare treatments for localised prostate cancer for men diagnosed in private and public health services in Victoria. DESIGN: Retrospective analysis of Victorian Cancer Registry data linked to population-based administrative health datasets. SETTING, PARTICIPANTS: 29 325 Victorian men diagnosed with prostate cancer during 2011-2017. MAIN OUTCOME MEASURES: Proportions of men in private and public health services receiving radical prostatectomy (with or without curative radiation therapy) or curative external beam radiation therapy alone within 12 months of diagnosis. RESULTS: After adjusting for age, tumour classification and comorbidity, men diagnosed in private health services received radical treatment more frequently than men diagnosed in public health services (odds ratio [OR], 1.40; 95% confidence interval [CI], 1.31-1.49). The proportion of private patients who underwent radical prostatectomy was larger than that for public patients (44% v 28%; OR, 2.28; 95% CI, 2.13-2.44) and the proportion of private patients who received curative external beam radiation therapy alone (excluding brachytherapy) was smaller (9% v 19%; OR, 0.45; 95% CI, 0.42-0.49). These differences were apparent for all International Society of Urological Pathology (ISUP) tumour grades. The magnitude of the difference for prostatectomy was greater for men aged 70 years or more; for radiation therapy alone, it was larger for those diagnosed before age 70. The differences between private and public services narrowed during 2011-2017 for men with ISUP grade 1 disease, but not ISUP grade 2-5 tumours. CONCLUSION: Prostate cancer treatment choices differ substantially between men diagnosed in private and public health services in Victoria. These differences are not explained by disease severity or comorbidity.

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

BACKGROUND AND PURPOSE: Inter-institutional studies highlighted correlation between consistent radiotherapy quality and improved overall patient survival. In treatment planning automation has the potential to address differences due to user-experience and training, promoting standardisation. The aim of this study was to evaluate implementation and clinical effect of a multicentre collaboratively-developed automated planning model for Intensity-Modulated Radiation Therapy/Volumetric-Modulated Arc Therapy of prostate. The model was built using a variety of public institutions' clinical plans, incorporating different contouring and dose protocols, aiming at minimising their variation. METHODS AND MATERIALS: A model using 110 clinically approved and treated prostate plans provided by different radiotherapy centres was built with RapidPlan (RP), for use on intact and post-prostatectomy prostate cases. The model was validated, distributed and introduced into clinical practice in all institutions. To investigate its impact a total of 126 patients, originally manually inverse planned (OP), were replanned using RP without additional planner manual intervention. Target and organ-at-risk (OAR) metrics were statistically compared between original and automated plans. RESULTS: For all centres combined and individually, RP provided plans comparable or superior to OP for all dose metrics. Statistically significant reductions with RP were found in bladder (V40Gy) and rectal (V50Gy) low doses (within 2.3% and 3.4% for combined and 4% and 10% individually). No clinically significant changes were seen for the PTV, independently of seminal vesicle inclusion. CONCLUSION: This project showed it is feasible to develop, share and implement RP models created with plans from different institutions treated with a variety of techniques and dose protocols, with the potential of improving treatment planning results and/or efficiency despite the original variability.

Testing the Assessment of New Radiation Oncology Technology and Treatments framework using the evaluation of post-prostatectomy radiotherapy techniques.

INTRODUCTION: We tested the ability of the Assessment of New Radiation Oncology Technology and Treatments framework to determine the clinical efficacy and safety of intensity-modulated radiation therapy (IMRT) compared with 3-dimensional radiation therapy (3DCRT) for post-prostatectomy radiation therapy (PPRT) to support its timely health economic evaluation. METHODS: Treatment plans produced using FROGG guidelines provided dosimetry parameters for both techniques at 64 Gy and 70 Gy and were also used to model early and late outcome probabilities. Clinical parameters were derived from early toxicity and quality of life patient data, systematic literature review and expert opinion. Dosimetry parameters were correlated with the measures of clinical efficacy and safety. RESULTS: Data from two patient cohorts (29 and 27 respectively) were collected within the project timeframe, providing evidence for acute toxicity and quality of life, and dosimetric comparisons. Relative rates of tumour control probability (TCP) and normal tissue control probability (NTCP) modelling were readily derived from the planning exercise and demonstrated advantages in uncomplicated TCP for IMRT over 3DCRT, predominantly due to normal tissue sparing. The safety of IMRT delivery was demonstrated with TCP uncompromised by IMRT protocol violations, which achieved rectal sparing only by reducing minimum target dose and coverage. CONCLUSION: Sources of desk-top and patient-based evidence were successfully used to demonstrate potential improved clinical efficacy and safety of applying dose escalation using IMRT instead of 3DCRT in PPRT.

A decision model to estimate the cost-effectiveness of intensity modulated radiation therapy (IMRT) compared to three dimensional conformal radiation therapy (3DCRT) in patients receiving radiotherapy to the prostate bed.

BACKGROUND: Intensity modulated radiation therapy (IMRT) is a radiation therapy technology that facilitates the delivery of an improved dose distribution with less dose to surrounding critical structures. This study estimates the longer term effectiveness and cost-effectiveness of IMRT in patients post radical prostatectomy. METHODS: A Markov decision model was developed to calculate the incremental quality adjusted life years (QALYs) and costs of IMRT compared with three dimensional conformal radiation therapy (3DCRT). Costs were estimated from the perspective of the Australian health care system. RESULTS: IMRT was both more effective and less costly than 3DCRT over 20 years, with an additional 20 QALYs gained and over $1.1 million saved per 1000 patients treated. This result was robust to plausible levels of uncertainty. CONCLUSIONS: IMRT was estimated to have a modest long term advantage over 3DCRT in terms of both improved effectiveness and reduced cost. This result was reliant on clinical judgement and interpretation of the existing literature, but provides quantitative guidance on the cost effectiveness of IMRT whilst long term trial evidence is awaited.

Novel 3D conformal technique for treatment of choroidal melanoma with external beam photon radiotherapy.

INTRODUCTION: To report a 3D conformal radiotherapy (3D-CRT) technique that utilises a specific eye immobilisation and treatment set-up method as an alternative to stereotactic radiotherapy (SRT), for treatment of juxtapapillary choroidal melanoma (CM) and report early treatment outcomes of this technique. METHODS: A contact lens and rod system was designed to provide eye immobilisation and a treatment reference point for 3D-CRT. The technique is described in detail in the body of the paper. A retrospective chart review was conducted to report freedom from local progression (FFLP) and radiation toxicity in a cohort of patients treated with a dose of 50 Gy in five fractions. RESULTS: Eleven eligible patients with juxtapapillary CM were treated between 2003 and 2009. The median follow-up was 3.2 years (range 1.2-5.3). The FFLP was 100% (95% confidence interval 71.5-100). The reproducibility of the set-up and eye immobilisation for fractionation was excellent. The mean dose to the planning target volume was 51.4 Gy (interquartilic range 51.0-51.9). Normal tissue dose constraints were achieved; however, the quality of the 3D-CRT plan was variable. The highest acute radiation toxicity score was Common Toxicity Criteria version 3 grade 1. Vision outcomes were poor. CONCLUSION: In this small series, a novel non-stereotactic technique was found to be an accurate method for the treatment of CM with a high rate of freedom from tumour progression, in keeping with the SRT series. The quality of the conformal plan was variable. Investigation of the optimal dose-fractionation schedule to minimise late radiation toxicity without compromise of tumour control is the focus of ongoing clinical research at our centre.

Reducing posttreatment dysphagia: Support for the relationship between radiation dose to the pharyngeal constrictors and swallowing outcomes.

PURPOSE: This study used prospective swallowing data to establish the following: (1) whether doses to the pharyngeal constrictor muscles (PCMs) were significantly associated with swallowing outcomes; and (2) a mean dose constraint to aim for in intensity modulated radiation therapy planning. METHODS AND MATERIALS: The PCMs were contoured and radiation dose data obtained for 55 patients with head and neck cancer. Associations between radiation dose and percentage of pharyngeal residue, penetration-aspiration and activity limitation measured at 6 months posttreatment were analyzed. Pretreatment swallowing function, tumor site, T classification, and chemotherapy were accounted for in multivariate analyses. RESULTS: On multivariate analysis, the percentage of pharyngeal residue was statistically significantly associated with the mean dose to the superior PCM (95% confidence interval [CI], 0.15-1.66; P = .02). Penetration-aspiration was associated with the mean dose to the superior, middle, and inferior PCMs (95% CI, 1.02-1.27; P = .003; 95% CI, 1.02-1.23; P = .003; 95% CI, 1.04-1.21; P = .003, respectively) and the mean dose to the total PCM (95% CI, 1.05-1.31; P = .001). Activity limitation was also associated with the mean dose to the superior, middle, and inferior PCMs (95% CI, 1.01-1.20; P = .02; 95% CI, 1.00-1.15; P =.04; 95% CI, 1.01-1.15; P = .02, respectively) and the mean dose to the total PCM (95% CI, 1.02-1.23; P = .01). On univariate analysis, all 3 swallowing measures were statistically significantly worse for patients who received a biologically equivalent mean dose of >60 Gy to the PCMs. This remained significant on multivariate analysis for both penetration-aspiration and activity limitation (95% CI, 2.05-58.2, P = .004 and 95% CI, 1.14-27.7, P = .03, respectively). CONCLUSIONS: The radiation dose to the PCMs is significantly associated with swallowing dysfunction. Limiting the mean PCM dose to less than 60 Gy results in better swallowing outcomes.

A dosimetric comparison of 3D conformal vs intensity modulated vs volumetric arc radiation therapy for muscle invasive bladder cancer.

BACKGROUND: To compare 3 Dimensional Conformal radiotherapy (3D-CRT) with Intensity Modulated Radiotherapy (IMRT) with Volumetric-Modulated Arc Therapy (VMAT) for bladder cancer. METHODS: Radiotherapy plans for 15 patients with T2-T4N0M0 bladder cancer were prospectively developed for 3-DCRT, IMRT and VMAT using Varian Eclipse planning system. The same radiation therapist carried out all planning and the same clinical dosimetric constraints were used. 10 of the patients with well localised tumours had a simultaneous infield boost (SIB) of the primary tumour planned for both IMRT and VMAT. Tumour control probabilities and normal tissue complication probabilities were calculated. RESULTS: Mean planning time for 3D-CRT, IMRT and VMAT was 30.0, 49.3, and 141.0 minutes respectively. The mean PTV conformity (CI) index for 3D-CRT was 1.32, for IMRT 1.05, and for VMAT 1.05. The PTV Homogeneity (HI) index was 0.080 for 3D-CRT, 0.073 for IMRT and 0.086 for VMAT. Tumour control and normal tissue complication probabilities were similar for 3D-CRT, IMRT and VMAT. The mean monitor units were 267 (range 250-293) for 3D-CRT; 824 (range 641-1083) for IMRT; and 403 (range 333-489) for VMAT (P < 0.05). Average treatment delivery time were 2:25min (range 2:01-3:09) for 3D-CRT; 4:39 (range 3:41-6:40) for IMRT; and 1:14 (range 1:13-1:14) for VMAT. In selected patients, the SIB did not result in a higher dose to small bowel or rectum. CONCLUSIONS: VMAT is associated with similar dosimetric advantages as IMRT over 3D-CRT for muscle invasive bladder cancer. VMAT is associated with faster delivery times and less number of mean monitor units than IMRT. SIB is feasible in selected patients with localized tumours.

Optimising the dosimetric quality and efficiency of post-prostatectomy radiotherapy: a planning study comparing the performance of volumetric-modulated arc therapy (VMAT) with an optimised seven-field intensity-modulated radiotherapy (IMRT) technique.

PURPOSE: The purpose of this study was to compare and evaluate radiotherapy treatment plans using volumetric modulated arc therapy (VMAT) and intensity modulated radiotherapy (IMRT) for post-prostatectomy radiotherapy. METHODS AND MATERIALS: The quality of radiotherapy plans for 10 patients planned and treated with a seven-field IMRT technique for biochemical failure post-prostatectomy were subsequently compared with 10 prospectively planned single-arc VMAT plans using the same computed tomography data set and treatment planning software. Plans were analysed using parameters to assess for target volume coverage, dose to organs at risk (OAR), biological outcomes, dose conformity and homogeneity, as well as the total monitor units (MU), planning and treatment efficiency. RESULTS: The mean results for the study population are reported for the purpose of comparison. For IMRT, the median dose to the planning target volume, V(95%) and D(95%) was 71.1 Gy, 98.9% and 68.3 Gy compared with 71.2 Gy, 99.2% and 68.6 Gy for VMAT. There was no significant difference in the conformity index or homogeneity index. The VMAT plans achieved better sparing of the rectum and the left and right femora with a reduction in the median dose by 7.9, 6.3 and 3.6 Gy, respectively. The total number of monitor units (MU) was reduced by 24% and treatment delivery time by an estimated 3 min per fraction without a significant increase in planning requirements. CONCLUSIONS: VMAT can achieve post-prostatectomy radiotherapy plans of comparable quality to IMRT with the potential to reduce dose to OAR and improve the efficiency of treatment delivery.

Does inverse-planned intensity-modulated radiation therapy have a role in the treatment of patients with left-sided breast cancer?

INTRODUCTION: The purpose of the study was to determine if multi-field inverse-planned intensity-modulated radiation therapy (IMRT) improves on the sparing of organs at risk (heart, lungs and contralateral breast) when compared with field-in-field forward-planned RT (FiF). METHODS: The planning CT scans of 10 women with left-sided breast cancer previously treated with whole-breast RT on an inclined breast board with both arms supported above the head were retrieved. The whole breast planning target volume (PTV) was defined by clinical mark-up and contoured on all relevant CT slices as were the organs at risk. For each patient, three plans were generated using FiF, five- and nine-field inverse-planned IMRT, all to a total dose of 50 Gy to the whole breast. Mean and maximum doses to the organs at risk and the homogeneity index (HI) of the whole-breast PTV were compared. RESULTS: The mean heart dose for the FiF plans was 2.63 Gy compared with 4.04 Gy for the five-field and 4.30 Gy for the nine-field IMRT plans, with no significant differences in the HI of the whole-breast PTV in all plans. The FiF plans resulted in a mean contralateral breast dose of 0.58 Gy compared with 0.70 and 2.08 Gy for the five- and nine-field IMRT plans, respectively. CONCLUSIONS: FiF resulted in a lower mean heart and contralateral breast dose with comparable HI of the whole-breast PTV in comparison with inverse-planned IMRT using five or nine fields.

Oncology staff reflections about a 52-year-old staff Christmas choir: constructivist research.

OBJECTIVE: Peter MacCallum Cancer Centre has one of the world's most enduring staff Christmas choirs. Commencing in 1956, the choir performs in a cafeteria, patient wards, and outpatient waiting areas before each Christmas. With recent emphasis on oncology staff support needs the choir's relevance warranted investigation. This constructivist research examined what effect the staff Christmas choir had on the choir members and staff bystanders in 2008. METHODS: Sampling was convenience and purposive. Staff choir members were invited to participate during rehearsals, and staff bystanders were invited at seven choir performances in the hospital. Respondents completed anonymous and semistructured questionnaires and the conductor (of 29 years) was interviewed. The inductive, comparative, and cyclic data analyses were informed by grounded theory and qualitative interrater reliability was performed. RESULTS: Questionnaires from 64 staff were returned. The choir elicited positive emotions, memories, Christmas spirit, hospital community and/or work-life effects for many staff, in a cancer context described as sometimes "overwhelming" and "stressful." Choir members' reactions included stress relief, friendship and feeling rewarded. Bystanders' reactions included feeling uplifted, inspired and moved. Suggestions for future performances were offered, including musical acknowledgement of other religious festivals. Two respondents were concerned about intrusive effects on patients and work practices. DISCUSSION: A staff Christmas choir supported most choir member and staff bystander respondents in an oncology hospital and is recommended in comparable contexts. Further investigation is warranted to extend understanding about Christmas music's effects in palliative care settings.

"The moment is all we have": patients and visitors reflect on a staff Christmas choir.

OBJECTIVE: To examine how performances by the Staff Christmas Choir of the Peter MacCallum Cancer Centre ("Peter Mac") affected inpatients, outpatients and visitors in 2008. DESIGN, SETTING AND PARTICIPANTS: During the Christmas season 2008, the Peter Mac Staff Christmas Choir gave seven performances at the Centre. Locations included inpatient wards, outpatient waiting areas and a cafeteria. To assess their response to the choir, oncology inpatients, outpatients and visitors (including early-departing bystanders) were given anonymous, semi-structured questionnaires during and after performances. To analyse the responses, we used a constructivist research approach informed by grounded theory. MAIN OUTCOME MEASURES: Participants' descriptions of the choir's effects on them. RESULTS: Questionnaires were returned by 111 people. The performances were received favourably by 93.7% of respondents, including nine from Jewish, Hindu or atheist backgrounds. Many said the music aroused positive emotions and memories. Several described transformative thoughts and physical reactions, felt affirmed by the Christmas spirit or message, and/or appreciated the peaceful or enlivened and social atmosphere. The choir also elicited personal perspectives about Christmas and Judaism, and the importance of "enjoying the moment". Only three respondents (2.7%) reported adverse effects, relating to emotional and audible intrusiveness. CONCLUSIONS: The Staff Christmas Choir created a supportive and uplifting atmosphere for many oncology patients and their visitors. However, responses from people from non-Christian backgrounds were limited, and further investigation is warranted to extend our understanding of the effect of Christmas music in Australian public health settings.

'Boomerang' technique: an improved method for conformal treatment of locally advanced nasopharyngeal cancer.

The primary aim of the present study was to assess radiation dosimetry and subsequent clinical outcomes in patients with locally advanced nasopharyngeal cancer using a novel radiation technique termed the 'Boomerang'. Dosimetric comparisons were made with both conventional and intensity modulated radiation therapy (IMRT) techniques. This is a study of 22 patients treated with this technique from June 1995 to October 1998. The technique used entailed delivery of 36 Gy in 18 fractions via parallel opposed fields, then 24 Gy in 12 fractions via asymmetric rotating arc fields for a total of 60 Gy in 30 fractions. Patients also received induction and concurrent chemotherapy. The radiation dosimetry was excellent. Dose-volume histograms showed that with the arc fields, 90% of the planning target volume received 94% of the prescribed dose. Relative to other conventional radiation therapy off-cord techniques, the Boomerang technique results in a 27% greater proportion of the prescribed dose being received by 90% of the planning target volume. This translates into an overall 10% greater dose received for the same prescribed dose. At 3 years, the actuarial loco-regional control rate, the failure-free survival rate and the overall survival rate were 91, 75 and 91%, respectively. At 5 years, the actuarial loco-regional control rate, the failure-free survival rate and the overall survival rate were 74, 62 and 71%, respectively. The Boomerang technique provided excellent radiation dosimetry with correspondingly good loco-regional control rates (in conjunction with chemotherapy) and very acceptable acute and late toxicity profiles. Because treatment can be delivered with conventional standard treatment planning and delivery systems, it is a validated treatment option for centres that do not have the capability or capacity for IMRT. A derivative of the Boomerang technique, excluding the parallel opposed component, is now our standard for patients with locally advanced nasopharyngeal cancer when IMRT is not available.

Exploring the effect of marked normal structure volume on normal tissue complication probability.

Radiation therapy dosimetry software now frequently incorporates biological predictions of the probability of normal tissue complications. This study investigates whether the length of normal structure outlined affects a normal tissue complication probability (NTCP) for that structure. It also researches the effect of any change in the dose parameter used to produce a 50% probability of a complication (the TD50) on the calculated NTCP, as this is related to the clinical observations. An NTCP was calculated for rectum and bladder on a sample of prostate cases receiving external beam radiation therapy. The length of the organs at risk was varied and the NTCP recalculated for each different length using the same treatment plan. Large variations of up to 80% in NTCP for different delineated lengths of organ for a given TD50 were observed. Changing the TD50 dose altered the calculated NTCP and the relative size of the variation in the values. This parameter will need further investigation; a standardized delineated length of 2 cm beyond the beam edge for normal structures is recommended. Interpatient and interinstitution plan comparison using dose volume histograms and/or normal tissue complication probabilities will be compromised until such standardization occurs.