• Dose levels outside radiotherapy beams.

      Greene, D; Chu, G L; Thomas, D W; Regional Department of Medical Physics and Bioengineering, Christie Hospital and Holt Radium Institute, Manchester M20 9BX (1983-08)
      The specification of a radiotherapy generator calls for the leakage radiation through the housing of the source to be 0.1% (the ICRP has recently (1982) changed this figure to 0.2% of the dose rate inside the useful beam). When a patient is irradiated, the dose level outside the useful beam is not only determined by this leakage radiation, but also by scattered radiation from the beam-defining system and from the treatment volume of the patient. Measurements have been made on a 300 kV X-ray unit, and on two different 4 MV and one 8 MV linear accelerators to determine the levels of leakage radiation and scattered radiation in air, and in a phantom comparable in size to the trunk of the patient. Similar measurements have also been made for a 15 MeV neutron generator. It is shown that for all these generators the dose delivered outside the radiation beam is determined mainly by the two scattering processes mentioned, and it is argued that for linear accelerators it would be feasible to increase the permitted level of leakage radiation by a factor of 2 or 3 without a significant increase in the stray radiation delivered to the patient.
    • Dose mapping from the target point of view.

      Vasquez Osorio, E; The University of Manchester c/o Christie Hospital- Dept 58- Floor 2A, Division of Molecular & Clinical Cancer Studies- School of Medical Sciences- Faculty of Biology-Medicine and Health, Manchester (2018)
    • Dose optimisation for assessment of periodontal structures in cone beam CT examinations.

      Al-Okshi, A; Theodorakou, Chrysoula; Lindh, C; Department of Oral and Maxillofacial Radiology, Faculty of Odontology, Malmo University, Malmo, Sweden (2016-12-02)
      To investigate the relationship between dose and image quality for a dedicated dental Cone Beam CT (CBCT) scanner using different scanning protocols and to set up an optimal imaging protocol for assessment of periodontal structures.
    • Dose rationalization of pembrolizumab and nivolumab using pharmacokinetic modeling and simulation and cost analysis.

      Ogungbenro, K; Patel, Alkesh; Duncombe, Robert; Nuttall, R; Clark, James; Lorigan, Paul C; Centre for Applied Pharmacokinetic Research, Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester Academic Health Science Centre, Manchester (2017-09-15)
      Pembrolizumab and nivolumab are highly selective anti-programmed cell death 1 (PD-1) antibodies approved for the treatment of advanced malignancies. Variable exposure and significant wastage have been associated with body size dosing of monoclonal antibodies (mAbs). The following dosing strategies were evaluated using simulations: body weight, dose banding, fixed dose, and pharmacokinetic (PK)-based methods. The relative cost to body weight dosing for band, fixed 150 mg and 200 mg, and PK-derived strategies were -15%, -25%, + 7%, and -16% for pembrolizumab and -8%, -6%, and -10% for band, fixed, and PK-derived strategies for nivolumab, respectively. Relative to mg/kg doses, the median exposures were -1.0%, -4.6%, + 27.1%, and +3.0% for band, fixed 150 mg, fixed 200 mg, and PK-derived strategies, respectively, for pembrolizumab and -3.1%, + 1.9%, and +1.4% for band, fixed 240 mg, and PK-derived strategies, respectively, for nivolumab. Significant wastage can be reduced by alternative dosing strategies without compromising exposure and efficacy.
    • Dose reduction in CT while maintaining diagnostic confidence: diagnostic reference levels at routine head, chest, and abdominal CT--IAEA-coordinated research project.

      Tsapaki, Virginia; Aldrich, John E; Sharma, Raju; Staniszewska, Maria Anna; Krisanachinda, Anchali; Rehani, Madan; Hufton, Alan P; Triantopoulou, Chariklia; Maniatis, Petros N; Papailiou, John; et al. (2006-09)
      PURPOSE: To measure radiation doses for computed tomography (CT) of the head, chest, and abdomen and compare them with the diagnostic reference levels, as part of the International Atomic Energy Agency Research coordination project. MATERIALS AND METHODS: The local ethics committees of all participating institutions approved the study protocol. Written informed consent was obtained from all patients. All scanners were helical single-section or multi-detector row CT systems. Six hundred thirty-three patients undergoing head (n = 97), chest (n = 243), or abdominal (n = 293) CT were included. Collected data included patient height, weight, sex, and age; tube voltage and tube current-time product settings; pitch; section thickness; number of sections; weighted or volumetric CT dose index; and dose-length product (DLP). The effective dose was also estimated and served as collective dose estimation data. RESULTS: Mean volumetric CT dose index and DLP values were below the European diagnostic reference levels: 39 mGy and 544 mGy . cm, respectively, at head CT; 9.3 mGy and 348 mGy . cm, respectively, at chest CT; and 10.4 mGy and 549 mGy . cm, respectively, at abdominal CT. Estimated effective doses were 1.2, 5.9, and 8.2 mSv, respectively. CONCLUSION: Comparison of CT results with diagnostic reference levels revealed the need for revisions, partly because the newer scanners have improved technology that facilitates lower patient doses.
    • Dose specification for hippocampal sparing whole brain radiotherapy (HS WBRT): considerations from the UK HIPPO trial QA programme.

      Megias, D; Phillips, M; Clifton-Hadley, L; Harron, E; Eaton, D; Sanghera, P; Whitfield, Gillian A; National Radiotherapy Trials Quality Assurance Group (RTTQA), Mount Vernon Hospital, London, UK (2017-01-06)
      The HIPPO trial is a UK randomised phase II trial of Hippocampal Sparing (HS) versus Conventional Whole Brain Radiotherapy after surgical resection or radiosurgery in favourable prognosis patients with 1-4 brain metastases. Each participating centre completed a planning benchmark case as part of the dedicated radiotherapy trials quality assurance programme (RTQA), promoting the safe and effective delivery of HS Intensity Modulated Radiotherapy (IMRT) in a multi-centre trial setting.
    • Dose surface maps of the heart can identify regions associated with worse survival for lung cancer patients treated with radiotherapy

      McWilliam, Alan; Dootson, C.; Graham, L.; Banfill, Kathryn; Abravan, Azadeh; van Herk, Marcel; Division of Clinical Cancer Science, School of Medical Sciences, Faculty of Biology, Medicine and Health, University of Manchester (2020)
      Background and purpose: For lung cancer patients treated with radiotherapy, radiation dose to the heart has been associated with overall survival, with volumetric dose statistics widely presented. However, critical cardiac structures are present on the hearts surface, where this approach may be sub-optimal. In this work we present a methodology for creating cardiac surface dose maps and identify regions where excess dose is associated with in worse overall survival. Material and methods: A modified cylindrical coordinate system was implemented to map the cardiac surface dose for lung cancer patients. Validation was performed by mapping the cardiac chambers for 55 patients, fitting a point spread function (PSF) to the blurred edge. To account for this uncertainty, dose maps were blurred by a 2D-Gaussian with width described by the PSF. Permutation testing identified regions where excess dose was associated with worse patient survival. The 99th percentile of the max t-value then defined a cardiac surface region to extract dose, from each patient, to be analysed in a multivariable cox-proportional hazards survival model. Results: Cardiac surface maps were created for 648 lung cancer patients. Cardiac surface dose maps were blurred with a 2D- Gaussian filter of size σφ = 4.3° and σy = 1.3units to account for mapping uncertainties. Permutation testing identified significant differences across the surface of the right atria, p < 0.001, at all timepoints. The median dose to the region defined by the 99th percentile of the maximum t-value was 18.5 Gy. Multivariable analysis showed the dose to this region was significantly associated with survival, hazard ratio 1.01 Gy-1, p = 0.03, controlling for confounding variables. Conclusions: Cardiac surface mapping was successfully implemented and identified a region where excess dose was associated with worse patient survival. This region extended over the right atria, potentially suggesting an interaction with the hearts electrical conduction system.
    • Dose surface maps of the heart identify dose sensitive regions

      McWilliam, Alan; Graham, L; Dootson, C; Abravan, Azadeh; Van Herk, Marcel; University of Manchester, Division of Cancer Science, Manchester, (2020)
      Purpose or Objective It has become accepted that for lung cancer patients the radiation dose to the heart is an independent predictor of survival. Analysis of dosimetric effects on the heart have investigated volumetric dose statistics, however potential critical cardiac structures are present on the heart surface. Volumetric parameters may not be optimal due to the required inter-patient registration accuracy. In this work we present a methodology for creating cardiac surface dose maps and use these to identify cardiac surface regions where excess dose results in worse patient survival. Material and Methods 648 cardiac surface maps were successfully created with a polar coordinate system with the centre positioned at the centre of mass for the heart contour of each slice in turn. This accounted for the asymmetric nature of the heart and can be considered a modified cylindrical coordinate system. The radiotherapy dose for each patient was sampled on this surface with the described coordinate system. All hearts were normalised to the same superior-inferior dimensions for analysis. For validation of the mapping, and localisation of dosimetric effects, the cardiac chambers were manually delineated and mapped onto the surface maps for 20 patients. A point spread function (PSF) was fitted to the blurred edge of the mapped chambers to quantify uncertainty in the mapping process. To account for this uncertainty, dose maps were blurred by a 2D-Guassian function with width described by the PSF. Permutation testing was used to identify regions where excess dose resulted in worse patient survival with the Tmap calculated. A threshold was set at the 99th percentile of the T-map and the dose from the cardiac surface each patient received extracted for analysis in a multi-variable cox-proportional hazards survival model. Results All surface maps were blurred with 2D-Guassian filter of size σφ=4.3° and σy = 1.3 units. Permutation testing for patients dead and alive at 6,12,18 and 24 months showed significant differences, p<0.001. The T-map for 18 months is included as figure 1 highlighting the highest significance region at the base of the heart and extending into the right and left atria. The mean dose to the region defined by the 99th percentile across all patients was 21.6Gy compared to the mean dose to the heart of 12.7Gy. Table 1 shows the multi-variable analysis where the dose to this region on the heart surface is significantly associated with survival, hazard ratio 1.014 per Grey, p=0.03, controlling for covariates including tumour volume. Conclusion We successfully created a modified cylindrical polar coordinate system for mapping radiotherapy dose to the heart. Surface maps identified a region near the base of the heart where excess dose results in worse patient survival. This region extends over the left and right atria close to the path of the coronary arteries suggesting these sub-structures are driving this effect.
    • Dose titration and patient selection increases the efficacy of GH replacement in severely GH deficient adults.

      Murray, Robert D; Skillicorn, C J; Howell, Simon J; Lissett, Catherine A; Rahim, Asad; Shalet, Stephen M; Department of Endocrinology, Christie Hospital, Manchester, UK. (1999-06)
      OBJECTIVE: Previous studies of GH replacement in adults have used unselected cohorts of GH deficient (GHD) adults and weight-based dosing regimens resulting in supraphysiological serum IGF-I levels and a high frequency of side-effects and withdrawal from these studies. By choosing patients with a high level of morbidity at baseline and using a low dose GH titration regimen we aimed to avoid over-replacement and increase the efficacy of treatment. DESIGN: An open study of GH replacement, initiating treatment with a dose of 0. 8 U/day and titrating the dose by 0.4 U increments to normalize the IGF-I SDS between - 2.0 and + 2.0 SD of the age-related normal range. PATIENTS: 65 severely GHD patients (peak GH < 9 mU/l to provocative testing), 25 males, of mixed adult and childhood-onset and mean age 38.7 (range 17-72) years. Inclusion criterion was that of subjectively poor quality of life on clinical interview. MEASUREMENTS: Height, weight, waist and hip circumference were measured to allow calculation of body mass index (BMI) and waist-hip ratio (WHR). Bone mineral density (BMD) was measured by dual X-ray absorptiometry (DEXA). Serum haemoglobin A1C (HbA1C), lipid profile and insulin like growth factor 1 (IGF-I) were measured. The Psychological General Well-Being Schedule (PGWB) and Adult Growth Hormone Deficiency Assessment (AGHDA) self-rating questionnaires (SRQ) were used to assess quality of life. RESULTS: Baseline characteristics were consistent with those previously described in severely GHD adults; mean IGF-I SDS - 2.4 (+/- 2.7), BMI 28.8 (+/- 5. 4) kg/m2, total cholesterol 6.17 (+/- 1.2) mmol/l, reduced BMD z-scores at the lumbar spine (- 0.8 +/- 1.2) and femoral neck (- 0. 44 +/- 1.4), and SRQ scores considerably lower than reported in previous studies of GH deficient adults and normal controls. Following initiation of GH serum IGF-I SDS was increased significantly from baseline to a mean level of 0.15 +/- 2.7 (P < 0. 001) and 0.31 +/- 2.0 (P < 0.001) at three and eight months, respectively. The mean PGWB score increased from 59.7 +/- 19.9 to 75. 8 +/- 15.0 (P < 0.001) and 73.7 +/- 19.5 (P = 0.001) at three and eight months, respectively. An increase of 14 points represents the largest improvement in quality of life, using this index, that has been reported in GHD adults. The mean AGHDA score also demonstrated considerable improvement, falling from 15.3 +/- 6.0 to 10.4 +/- 6.2 (P < 0.001) and 9.8 +/- 6.5 (P < 0.001) at three and eight months, respectively. The changes observed in both the PGWB and AGHDA scores between baseline and at both three and eight months were shown to correlate significantly with the respective baseline score. A significantly greater improvement was observed in the PGWB following GH replacement in those with a baseline PGWB score of < 60 than in those with a score > 60. This observation was significant at both three (27.1 vs 6.7, P = 0.0001) and eight (25.6 vs 3.3, P = 0.0003) months. All PGWB subscales showed significant improvement though that of vitality was of greatest magnitude. A strong correlation was observed between the generic and disease-specific SRQ (r = - 0.73, P < 0.001). CONCLUSIONS: The observed improvement in quality of life in GH deficient adults is proportional to the degree of impairment before commencing therapy. The use of low-dose titration and selection of a population with greater morbidity reduces the occurrence of over-replacement and increases the efficacy of treatment. This allows direction of resources to those in greatest need.
    • Dose-dense cisplatin with gemcitabine for relapsed platinum-resistant ovarian cancer.

      Morgan, Robert David; Clamp, Andrew R; Zhou, Cong; Saunders, Geoff; Mescallado, Nerissa; Welch, Richard; Mitchell, Claire L; Hasan, Jurjees; Jayson, Gordon C; The Christie NHS Foundation Trust, Manchester, UK (2019)
      INTRODUCTION: Standard of care treatment for women who develop relapsed ovarian cancer includes sequential platinum- and/or paclitaxel-based chemotherapy, with reducing disease-free intervals. Once platinum resistance develops, treatment options become limited and dose-dense regimens may be offered. We report the efficacy and safety of dose-dense cisplatin with gemcitabine chemotherapy for relapsed platinum-resistant ovarian cancer. METHODS: A retrospective analysis of all patients with relapsed, platinum-resistant ovarian, primary peritoneal or fallopian tube cancer treated with cisplatin 35 mg/m2 of body surface area by intravenous infusion with gemcitabine 1000 mg/m2 of body surface area by intravenous infusion on days 1 and 8 of every 21-day treatment cycle between 1 January 2009 and 1 June 2017. RESULTS: Ninety-four eligible patients had received a median of three (range one-eight) prior lines of cytotoxic therapy for relapsed ovarian cancer. Sixty patients (64%) had received ? 1 prior dose-dense chemotherapy regimen. Dose-dense cisplatin with gemcitabine was associated with a median progression-free survival (PFS) of 4.4 months (95% CI 3.6 to 5.3) and overall survival of 7.6 months (95% CI 5.6 to 9.6). The median PFS for dose-dense cisplatin with gemcitabine as first- (n = 34), second- (n = 42), and third-line or later (n = 18) dose-dense therapy was 4.2 (95% CI 3.2 to 5.2), 5.0 (95% CI 3.5 to 6.5), and 4.2 (95% CI 3.3 to 5.1) months respectively. The RECIST objective response rate for first-, second-, and third-line dose-dense cisplatin with gemcitabine was 23%, 14 %, and 7 % respectively. The most common grade 3 - 4 adverse events were thrombocytopenia (20%), anemia (18%), and neutropenia (14%). DISCUSSION: Dose-dense cisplatin with gemcitabine provides modest efficacy whether it is used as a first- or subsequent line of dose-dense chemotherapy to treat relapsed platinum-resistant ovarian cancer and the toxicity is manageable with supportive measures.
    • Dose-escalated hypofractionated intensity-modulated radiotherapy in high-risk carcinoma of the prostate: outcome and late toxicity.

      Thomson, David J; Merrick, S; Swindell, Ric; Coote, Joanna H; Kelly, K; Stratford, Julia; Wylie, James P; Cowan, Richard A; Elliott, Tony; Logue, John P; et al. (2012)
      Background. The benefit of dose-escalated hypofractionated radiotherapy using intensity-modulated radiotherapy (IMRT) in prostate cancer is not established. We report 5-year outcome and long-term toxicity data within a phase II clinical trial. Materials and Methods. 60 men with predominantly high-risk prostate cancer were treated. All patients received neoadjuvant hormone therapy, completing up to 6 months in total. Thirty patients were treated with 57 Gy in 19 fractions and 30 patients with 60 Gy in 20 fractions. Acute and 2-year toxicities were reported and patients followed longitudinally to assess 5 year outcomes and long-term toxicity. Toxicity was measured using RTOG criteria and LENT/SOMA questionnaire. Results. Median followup was 84 months. Five-year overall survival (OS) was 83% and biochemical progression-free survival (bPFS) was 50% for 57 Gy. Five-year OS was 75% and bPFS 58% for 60 Gy. At 7 years, toxicity by RTOG criteria was acceptable with no grade 3 or above toxicity. Compared with baseline, there was no significant change in urinary symptoms at 2 or 7 years. Bowel symptoms were stable between 2 and 7 years. All patients continued to have significant sexual dysfunction. Conclusion. In high-risk prostate cancer, dose-escalated hypofractionated radiotherapy using IMRT results in encouraging outcomes and acceptable late toxicity.
    • Dose-escalating induction chemotherapy supported by lenograstim preceding high-dose consolidation chemotherapy for advanced breast cancer. Selection of the most acceptable regimen to induce maximal tumor response and investigation of the optimal time to collect peripheral blood progenitor cells for haematological rescue after high-dose consolidation chemotherapy.

      Van Hoef, M E; Baumann, Irith; Lange, C; Luft, T; De Wynter, Erika A; Ranson, Malcolm R; Morgenstern, Godfrey R; Yvers, A; Dexter, T Michael; Testa, Nydia G; et al. (1994-03)
      BACKGROUND: In advanced breast cancer high-dose consolidation chemotherapy with haematological rescue has resulted in prolonged disease free and overall survival in a small percentage of patients. Maximal reduction of the tumor burden by intensive induction treatment preceding the high-dose chemotherapy may favor that outcome. The aims of this study were to find a rapid highly effective induction regimen with acceptable toxicity and to examine the optimal time for peripheral blood progenitor cell (PBPC) collection for haematological rescue. SUBJECTS AND METHODS: Twenty-four patients received 4 cycles of FAC chemotherapy (5-FU, adriamycin, cyclosphamide), each followed by 10 micrograms/kg/d of lenograstim (glycosylated rHuG-CSF) s.c. day 2 to 11. Chemotherapy was administered at 4 dose intensity levels with 6 patients including at each level (level 1: 500(F)/50(A)/500(C) mg/m2/3wk, level 2: 500/50/500 mg/m2/2wk, level 3: 500/75/500 mg/m2/2wk, m2/2wk, level 4: 500/75/1000 mg/m2/2wk d1 i.v.). In addition lenograstim (10 micrograms/kg/d s.c.) was administered for a period of 10 days before (period X) and after (period Y) chemotherapy. In 16 patients (4 at each dose intensity level) assessment of PBPC was performed during period X and Y as well as during cycle 1 and 4. A single apheresis to collect PBPC was planned during chemotherapy cycle 1. RESULTS: The best response was obtained at dose intensity level 3 (all 6 patients responded, 3 of them achieved CR) with acceptable toxicity. Peak circulating numbers of total CFC/ml blood were median 5819 (period X), 4635 (cycle 1), 3807 (cycle 4) and 3519 (period Y) and occurred concurrently with peak circulating numbers of CD34+ cells. The and median 3.76 x 10(6)/kg CD34+ cells. Three patients received high-dose consolidation chemotherapy with PBPC support. Recovery of ANC > 0.5 x 10(9)/l occurred on median day 11 and of platelets > 20 x 10(9)/l on median day 10. CONCLUSION: Dose intensity level 3 is the best usable induction regimen in this study. The optimal time for apheresis is either during lenograstim before chemotherapy treatment or during the first cycle of chemotherapy. Rapid haematological recovery was obtained by reinfusion of PBPC as sole source of support in the patients receiving high-dose consolidation chemotherapy.
    • Dose-finding study of fixed dose gemcitabine and escalating doses of ifosfamide given on days 1 and 8 in patients with advanced non-small cell lung cancer.

      Baka, Sofia; Manegold, Christian; Buchholz, Erika; Schott-von-Römer, K; Lorigan, Paul C; Nagel, Sylke; Blackhall, Fiona H; Ashcroft, Linda; Thatcher, Nick; Department of Medical Oncology, Christie Hospital NHS Trust, Wilmslow Road, Withington, Manchester M20 4BX, UK. bakasofia@hotmail.com (2006-08)
      This is a dose-finding study of fixed dose gemcitabine and escalating doses of ifosfamide, in chemo naïve patients with advanced non-small cell lung cancer. The purpose of the study was to determine the optimal dosage and the maximal tolerated dose (MTD) of a specified schedule of gemcitabine and ifosfamide. Patients received gemcitabine 1250 mg/m2 and ifosfamide between 1.6 and 2.2 g/m2, intravenously, on days 1 and 8, repeated every 3 weeks for a maximum of four cycles. RESULTS: Sixteen patients entered the study. Three patients were entered at the first dose level of ifosfamide (1.6 g/m2) and none experienced any dose limiting (DLT) toxicity. In dose level 2 (1.8 g/m2), two patients had grade IV haematological toxicities, but they reached 21 days without any other dose limiting toxicity (DLT). Three further patients entered at this level but they were withdrawn due to disease progression. The sixth patient entered without any DLT. Three patients entered dose level 3 (2.0 g/m2), without any grade IV toxicity. The first patient entered into dose level 4 (2.2 g/m2), had progressive disease within 21 days and was withdrawn and another three were entered and had no DLT during the first 21 days. Four (33%) of the patients had stable disease and 67% had progressive disease. CONCLUSION: The MTD of the ifosfamide gemcitabine combination was not reached in the present study, as no DLT was observed. This combination at the dose levels of this protocol has little or no activity in patients with advanced NSCLC.
    • Dose-rate considerations in the introduction of low-dose-rate afterloading intracavitary techniques for radiotherapy.

      Wilkinson, John M; Hendry, Jolyon H; Hunter, Robin D; Departments of Physics and Radiotherapy, and Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester M20 9BX (1980-09)
      An investigation has been made into the changes in total dose required as a consequence of proposed increases in dose-rate in low-dose-rate treatments of cancer of the uterine cervix. The relationship between total irradiation time and dose-rate has been measured using an assay based on mouse-tail radionecrosis, with irradiation schedules similar to existing and proposed human cervix treatments. This relationship, which is similar to that observed in other biological systems, predicts that the total dose for epithelial tolerance should be reduced by about one third when the dose-rate is increased from 1.0 to 3.5 Gy per hour. The clinical implications of this finding are discussed.
    • Dosimetric comparison of five different techniques for craniospinal irradiation across 15 European centers: analysis on behalf of the SIOP-E-BTG (radiotherapy working group).

      Seravalli, E; Bosman, M; Lassen-Ramshad, Y; Vestergaard, A; Oldenburger, F; Visser, J; Koutsouveli, E; Paraskevopoulou, C; Horan, G; Ajithkumar, T; et al. (2018-04-26)
      Conventional techniques (3D-CRT) for craniospinal irradiation (CSI) are still widely used. Modern techniques (IMRT, VMAT, TomoTherapy®, proton pencil beam scanning [PBS]) are applied in a limited number of centers. For a 14-year-old patient, we aimed to compare dose distributions of five CSI techniques applied across Europe and generated according to the participating institute protocols, therefore representing daily practice.
    • A dosimetric intercomparison of megavoltage photon beams in UK radiotherapy centres.

      Thwaites, D I; Williams, J R; Aird, E G; Klevenhagen, S C; Williams, Peter C; Department of Medical Physics and Medical Engineering, University of Edinburg, UK. (1992-02)
      A dosimetry intercomparison has been carried out for all 64 radiotherapy centres in the UK. Doses were measured with an ionization chamber in an epoxy resin water-substitute phantom of relatively simple geometry. Reference-point measurements were made for all MV photon beams. For 61 Co-60 beams, a mean ratio of measured-to-stated dose of 1.002 was observed with a standard deviation of 0.014, whilst for 100 MV x-ray beams, the corresponding figures were 1.003 and 0.015. 97% of beams lay within a +/- 3% deviation. One measurement was instrumental in discovering a large discrepancy. Doses were also investigated in two planned three-field distributions at one beam quality in each centre. One of these was in a homogeneous phantom, whilst the second included a lung-equivalent insert. Doses were measured at the central point and at four other points in the high dose volume. In both situations, the mean ratio of measured-to-calculated doses for all points was 1.008, with standard deviations of 0.027 and 0.035 for the uniform and non-uniform phantoms, respectively. Discrepancies over 5% were followed up. The work must be viewed in the context of other international intercomparisons and is an essential part of wider radiotherapy audit processes.
    • Dosimetric predictors of radiotherapy-induced lymphocytopenia in lung cancer

      Joseph, N.; Choudhury, Ananya; Ministry of Health, Colombo, Sri Lanka; Sri Lanka Cancer Research Group, Maharagama, Sri Lanka. (2021)
    • Dosimetry audit for a multi-centre IMRT head and neck trial.

      Clark, Catharine H; Hansen, Vibeke Nordmark; Chantler, Hannah; Edwards, Craig; James, Hayley V; Webster, Gareth J; Miles, Elizabeth; Guerrero Urbano, M Teresa; Bhide, Shree A; Bidmead, A Margaret; et al. (2009-10)
      BACKGROUND AND PURPOSE: PARSPORT was a multi-centre randomised trial in the UK which compared Intensity-Modulated Radiotherapy (IMRT) and conventional radiotherapy (CRT) for patients with head and neck cancer. The dosimetry audit goals were to verify the plan delivery in participating centres, ascertain what tolerances were suitable for head and neck IMRT trials and develop an IMRT credentialing program. MATERIALS AND METHODS: Centres enrolling patients underwent rigorous quality assurance before joining the trial. Following this each centre was visited for a dosimetry audit, which consisted of treatment planning system tests, fluence verification films, combined field films and dose point measurements. RESULTS: Mean dose point measurements were made at six centres. For the primary planning target volume (PTV) the differences with the planned values for the IMRT and CRT arms were -0.6% (1.8% to -2.4%) and 0.7% (2.0% to -0.9%), respectively. Ninety-four percent of the IMRT fluence films for individual fields passed gamma criterion of 3%/3mm and 75% of the films for combined fields passed gamma criterion 4%/3mm (no significant difference between dynamic delivery and step and shoot delivery). CONCLUSIONS: This audit suggests that a 3% tolerance could be applied for PTV point doses. For dose distributions tolerances of 3%/3mm on individual fields and 4%/3mm for combined fields are proposed for multi-centre head and neck IMRT trials.
    • Dosimetry for fractionated ZevalinTM treatment as an initial therapy of follicular lymphoma.

      Malek, E; Ferrer, L; Bardies, M; Bodet-Milin, C; Kraeber-Bodere, F; Huglo, D; LeGouill, S; Prangere, T; Robu, D; Tipping, Jill; et al. (2010-10)
    • The dosimetry of the radiation from californium-252.

      Greene, D; Major, D; Christie Hospital and Holt Radium Institute, Manchester (1974-07)