Radiotherapy Quality Control Research Articles

Conformal radiotherapy, reduced boost volume, hyperfractionated radiotherapy, and online quality control in standard-risk medulloblastoma without chemotherapy: Results of the French M-SFOP 98 protocol

Between December 1998 and October 2001, patients <19 years old were treated for standard-risk medulloblastoma according to the Medulloblastome-Société Française d'Oncologie Pédiatrique 1998 (M-SFOP 98) protocol. Patients received hyperfractionated radiotherapy (36 Gy in 36 fractions) to the craniospinal axis, a boost with conformal therapy restricted to the tumor bed (to a total dose of 68 Gy in 68 fractions), and no chemotherapy. Records of craniospinal irradiation were reviewed before treatment start. A total of 48 patients were considered assessable. With a median follow-up of 45.7 months, the overall survival and progression-free survival rate at 3 years was 89% and 81%, respectively. Fourteen major deviations were detected and eight were corrected. No relapses occurred in the frontal region and none occurred in the posterior fossa outside the boost volume. Nine patients were available for volume calculation without reduction of the volume irradiated. We observed a reduction in the subtentorial volume irradiated to >60 Gy, but a slight increase in the volume irradiated to 40 Gy. No decrease in intelligence was observed in the 22 children tested during the first 2 years. This hyperfractionated radiotherapy protocol with a reduced boost volume and without chemotherapy was not associated with early relapses in children. Moreover, intellectual function seemed to be preserved. These results are promising.

461 oral Quality control of involved-field radiotherapy in patients with advanced stage Hodgkin's lymphoma (HL) enrolled on the EORTC trial 20884

461 oral Quality control of involved-field radiotherapy in patients with advanced stage Hodgkin's lymphoma (HL) enrolled on the EORTC trial 20884

Radiotherapy (RT) and concomitant and adjuvant temozolomide (TMZ) versus radiotherapy alone for newly diagnosed glioblastoma (GBM): Overall results and recursive partitioning analysis (RPA) of a phase III randomized trial of the EORTC brain tumor and radiotherapy groups and the NCIC clinical trial group

The standard initial treatment for patients with GBM after biopsy or surgical resection is post-operative radiotherapy. Chemotherapy was shown to have only a minimal impact on outcome. In a previous phase II trial, we have suggested that adding TMZ to RT might improve survival (Stupp et al. JCO 20:1375–1382, 2002). In EORTC 26981/22981 NCIC CE3 we compared the efficacy of concomitant and adjuvant TMZ and RT to RT alone. Patients with newly diagnosed and histologically proven GBM (WHO grade IV), PS (WHO) 0–2, age 18–70 were eligible. The randomization was between standard RT (60 Gy in 30 daily fractions of 2 Gy, with a GTV-CTV margin of 2–3 cm), versus the same RT with concomitant TMZ (75 mg/m2 daily 7d/week for 35–42 d), followed by up to 6 cycles of adjuvant TMZ (150–200 mg/m2, daily × 5 d, q 28 d). Patients were stratified for institution, age, PS and extent of surgery. Primary endpoint was overall survival (OS) and secondary endpoints were progression free survival (PFS), quality of life and full toxicity profile. Pathology was centrally reviewed and quality control for RT was assessed by individual case reviews. Between July 2000 and March 2002, a total of 573 patients were randomized by 85 institutions. Sixteen percent of patients had a biopsy only, and 84 % had either partial (44 %) or complete (40 %) surgical tumor removal. Median age was 56 years (19–70.5), 63 % were male. PS was 0, 1 and 2 in 39 %, 48 % and 13 % of patients respectively. There was no difference in the prognostic factors between the two treatment arms. RT was delivered as prescribed in 93 % of patients, concomitant TMZ was administered without interruption in 76 % and temporarily interrupted in 11 %. Adjuvant TMZ was given to 76 % of patients and 36 % completed all 6 cycles. With a median follow-up of 2 years, 436 patients have died, 241 (84 %) in the control (RT only) arm and 195 (68 %) in the experimental (RT/TMZ) arm. Median survival was 12 months (95% c.i. 11.2–13.2) in the RT arm and 15 months (95% c.i. 13.6–16.8) in the RT/TMZ arm (p < .0001), and 2 year survivals were 8 % (95% c.i. 4–12 %) and 26 % (95% c.i. 20–32 %), respectively (p < .0001). The difference between the two treatment arms remained statistically significant in RPA classes III-V. Additional results and detailed analysis of prognostic classes will be presented. Concomitant and adjuvant TMZ/RT significantly improves overall survival compared to RT alone in newly diagnosed glioblastoma, regardless of the prognostic class

Conformal radiotherapy, reduced boost volume, hyperfractionnated radiotherapy and on-line quality control in standard risk medulloblastoma without chemotherapy, results of the french M-SFOP 98 protocol

Conformal radiotherapy, reduced boost volume, hyperfractionnated radiotherapy and on-line quality control in standard risk medulloblastoma without chemotherapy, results of the french M-SFOP 98 protocol

Quality control in radiotherapy of brain tumors

(Conclusion) Radiotherapy techniques for brain tumors are complex and require precision in planning and giving radiotherapy programs. Continual application of quality control should enable achieving better treatment results with minimizing risk for late treatment-related complications. Introduction of uniform and precise parameters for the therapy planning, dose determining and patient's control, makes possible for optimal follow-up and comparison of treatment results between different therapeutic centers.

261 poster Evaluation of film measurement based dose distributions for conformal radiotherapy quality control

261 poster Evaluation of film measurement based dose distributions for conformal radiotherapy quality control

Formalisms for MU calculations, ESTRO booklet 3 versus NCS report 12

Although the relevance and importance of quality assurance and quality control in radiotherapy is generally accepted, only recently, methods for monitor unit (MU) calculation and verification have been addressed in recognized recommendations, published by the European Society of Therapeutic Radiation Oncology (ESTRO) and by the Netherlands Commission on Radiation Dosimetry (Dutreix A, Bjärngard BE, Bridier A, Mijnheer B, Shaw JE, Svensson H. Monitor unit calculation for high-energy photon beams. Physics for clinical radiotherapy. ESTRO Booklet No. 3. Leuven: Garant, 1997; Netherlands Commission on Radiation Dosimetry (NCS). Determination and use of scatter correction factors of megavoltage photon beams. NCS report 12. Deift: NCS, 1998). Both documents are based on the same principles: (i) the separation of the output factor into a head and a volume (or phantom) scatter component; (ii) the use of a so-called mini-phantom to measure and verify the head scatter component; and (iii) the recommendation to use a single reference depth of 10 cm for all photon beam qualities. However, there are substantial differences between the approach developed in the IAEA-ESTRO task group and the NCS approach for MU calculations, which might lead to confusion and/or misinterpretation if both reports are used simultaneously or if data from the NCS report is applied in the algorithms of the ESTRO report without careful consideration. The aim of the present paper is to discuss and to clearly point out these differences (e.g. field size definitions, phantom scatter parameters, etc.). Additionally, corresponding quantities in the two reports are related where possible and several aspects concerning the use of a mini-phantom (e.g. size, detector position, composition) are addressed.

A survey of radiotherapy quality control practice in the United Kingdom for the START trial

Background and purpose: This paper compares the quality control checks performed in departments in the United Kingdom with those recommended by the Institute of Physics and Engineering in Medicine (IPEM) in Report 81. Method: The data were gathered by the quality assurance team for the START trial, during visits to individual departments. Data are compared with the frequencies suggested in IPEM report 81. Where applicable, data are also analyzed with respect to machine manufacturer. Results: All departments with linear accelerators check the output at least weekly for both photons and electrons, however 11% of departments do not perform a constancy check of the output on a daily basis. The majority of departments check flatness at gantry zero on a monthly basis. However 27% of departments never check at non-zero gantry angles. In 51% of departments no fluoroscopy checks are performed on simulators on a daily basis. Conclusion: The majority of departments are following the frequencies suggested in IPEM report 81 although there are a number of discrepancies particularly for simulators. Accelerator type needs to be considered when designing quality assurance checks. In many departments more time than is currently allocated is needed on equipment, particularly simulators, to complete all of the checks suggested in Report 81.

Clinical governance: risks and quality control in radiotherapy

The professions involved in radiotherapy constantly strive to improve quality and to minimize errors and their effects. We are aware of our shortcomings but sometimes are powerless to take corrective action. We have seen that clinical governance requires some change in the medical culture but much has yet to be achieved in the standardization of medical processes. We would gain by sharing experiences of system failures, whether that be by reporting near misses or by disseminating details of litigation cases. In a specialty that depends on human processes and interactions, it is no surprise to find a measurable incidence of human errors. Sometimes this is also related to technological or design deficiencies and we rely too much on human interventions to overcome these. We would like to take positive steps to improve quality, such as those inherent in the new ISO9000 standards, but we are hindered by a variety of constraints--manpower, old technology, pressure to achieve high patient throughput. We need to make decisions for the future development of radiotherapy in the UK. We could settle for a system that is characterized by high throughput and high risk. Hopefully, we will receive the necessary encouragement and resources to strive for high standards of treatment and low risk.

Real-time three-dimensional motion analysis for patient positioning verification

Background and purpose: This paper describes the technology and methods involved in a system for automatically checking the position of patients at radiotherapy units. This is proposed for improving the accuracy in the irradiation geometrical set-up, which is a crucial factor in radiotherapy quality control. Materials and methods: The system is based on real-time opto-electronics and close-range photogrammetry and detects multiple passive markers placed on selected patient skin landmarks. Patient alignment and position monitoring is carried out by comparing the current three-dimensional positions of the markers with those of an initial reference position acquired during the simulation procedure and/or the first irradiation session. The system was used to measure the accuracy of conventional laser centering techniques for patient repositioning. Inaccuracies due to breathing and random movements were also taken into account. Professional technicians were asked to reposition three volunteer subjects carefully using a traditional laser centering procedure. Results: The results revealed significant repositioning errors even in highly controlled conditions, affecting particularly body areas relatively far from the skin reference points used for laser alignment. Conclusions: The outcome of the experimental application of this technology confirms its potential as a tool for patient repositioning and automatic detection of any errors caused by breathing or other unpredictable movements. The real-time feedback on the patient's position given by the system provides operators with appropriate visual indices and allows them to take suitable countermeasures in case of significant failures. In addition, the use of the system output for automatic position control is envisaged.

Postoperative neoadjuvant chemotherapy before radiotherapy as compared to immediate radiotherapy followed by maintenance chemotherapy in the treatment of medulloblastoma in childhood: results of the german prospective randomized trial hit ’91

Purpose: The German Society of Pediatric Hematology and Oncology (GPOH) conducted a randomized, prospective, multicenter trial (HIT ’91) in order to improve the survival of children with medulloblastoma by using postoperative neoadjuvant chemotherapy before radiation therapy as opposed to maintenance chemotherapy after immediate postoperative radiotherapy. Methods and Materials: Between 1991 and 1997, 158 patients were enrolled and 137 patients randomized. Seventy-two patients were allocated to receive neoadjuvant chemotherapy before radiotherapy (arm I, investigational). Chemotherapy consisted of ifosfamide, etoposide, intravenous high-dose methotrexate, cisplatin, and cytarabine given in two cycles. In arm II (standard arm), 65 patients were assigned to receive immediate postoperative radiotherapy, with concomitant vincristine followed by 8 cycles of maintenance chemotherapy consisting of cisplatin, CCNU, and vincristine (“Philadelphia protocol”). All patients received radiotherapy to the craniospinal axis (35.2 Gy total dose, 1.6 Gy fractionated dose / 5 times per week followed by a boost to posterior fossa with 20 Gy, 2.0 Gy fractionated dose). Results: During chemotherapy Grade III/IV infections were predominant in arm I (40%). Peripheral neuropathy and ototoxicity were prevailing in arm II (37% and 34%, respectively). Dose modification was necessary in particular in arm II (63%). During radiotherapy acute toxicity was mild in the majority of patients and equally distributed in both arms. Myelosuppression led to a mean prolongation of treatment time of 11.5 days in arm I and 7.5 days in arm II, and interruptions in 35% of patients in arm I. Quality control of radiotherapy revealed correct treatment in more than 88% for dose prescription, more than 88% for coverage of target volume, and 98% for field matching. At a median follow-up of 30 months (range 1.4–62 months), the Kaplan-Meier estimates for relapse-free survival at 3 years for all randomized patients were 0.70 ± 0.08; for patients with residual disease: 0.72 ±0.06; without residual disease: 0.68 ± 0.09; M0: 0.72 ± 0.04; M1: 0.65 ± 0.12; and M2/3: 0.30 ± 0.15. For all randomized patients without M2/3 disease: 0.65± 0.05 (arm I) and 0.78 ± 0.06 (arm II) ( p < 0.03); patients between 3 and 5.9 years: 0.60 ± 0.13 and 0.64 ± 0.14, respectively, but patients between 6 and 18 years: 0.62 ± 0.09 and 0.84 ± 0.08, respectively ( p < 0.03). In a univariate analysis the only negative prognostic factors were M2/3 disease ( p < 0.002) and an age of less than 8 years ( p < 0.03). Conclusions: Maintenance chemotherapy would seem to be more effective in low-risk medulloblastoma, especially in patients older than 6 years of age. Neoadjuvant chemotherapy was accompanied by increased myelotoxicity of the subsequent radiotherapy, causing a higher rate of interruptions and an extended overall treatment time. Delayed and/or protracted radiotherapy may therefore have a negative impact on outcome. M2/3 disease was associated with a poor survival in both arms, suggesting the need for a more intensive treatment. Young age and M2/3 stage were negative prognostic factors in medulloblastoma, but residual or M1 disease was not, suggesting a new stratification system for risk subgroups. High quality of radiotherapy may be a major contributing factor for the overall outcome.

Localization and System Integration Tests as Quality Assurance for the Leksell γ-Unit

Quality control in stereotactic radiotherapy of brain lesions with the Leksell γ-unit or the LINAC-facility is a must, as missing the target is the most serious error that can occur in that kind of treatment. We developed a quality assurance program to reduce this risk. To evaluate the accuracy of the procedure, which defines the target, including all possible errors of the therapy chain, irradiations of phantoms were performed, using the so-called “known” and “unknown” target method. Accuracy is defined by the deviation of the irradiated target from the calculated target with digital images used for therapy planning. GafChromic MD-55 films, which have been irradiated by means of a special author-developed phantom, were applied for measuring the precision of the radiation unit. The results obtained for isocentric accuracy of the Leksell γ-unit were in good agreement with the measurements of the manufacturing company. The deviation measured with the 4-mm collimator helmet was up to 0.3 mm, including the CT images and the stereotactic frame less than 0.85 mm, respectively. The phantom designed for this purpose is useful in quality assurance measurements of this stereotactic therapy chain.

307 Impact of quality control on treatment outcome

Quality control in radiotherapy reinforces the quality established within the framework of general programs of quality assurance. The control applies to the most critical aspects of treatment, thus enabling the elimination of systematic and sometimes random errors. Can quality control have an impact on treatment outcome? In radiotherapy, the result is dependent on several factors, starting with the exactitude of the initial diagnosis and ending with the therapeutic follow-up. In the literature, data show that some loco-regional failure and, in certain cases, the decrease in survival can be attributed to treatment error. Quality control in radiotherapy enables the analysis. of various typical errors and their consequence, particularly with regard to target volumes, irradiation fields, dose, or errors in calculation. This knowledge can limit errors to a minimum. Various systems, more or less sophisticated, should be able to limit errors before or during the treatment. Quality control leads to the improvement of treatment outcome; some examples will be given. However, these results are not always obvious. Quality control has a role to play in certain clinical circumstances which are difficult to analyze without precise and objective information on patient outcome. It can be an important component in the treatment of localizations that have had mediocre results. Besides its contribution to the improvement of local control and survival, quality control can also be an essential means of improving and decreasing post-therapeutic complications.

Measurement possibilities using an electronic portal imaging device

A vital role in the quality control of radiotherapy is the use of portal imaging for verifying field size, shape, orientation and patient set-up. Coincidence of treated volume and target volume is imperative. Electronic portal imaging devices are effective at providing this verification. However, these devices are versatile enough to be used in other ways pertinent to the delivery of high quality, high precision radiotherapy. This paper examines two such ways: in assessing the reproducibility of a multileaf collimator system, and in determining exit doses in vivo. Configured as a dosimeter, the system shows a linear response with good dynamic range. Its high spatial resolution was used to show that leaf positioning was reproducible to within 0.5 mm for all tested gantry and collimator angles. Our preliminary results from this exit dosimetry technique demonstrate that, under specific conditions, doses can be determined to within 2.5% of that measured using silicon diodes or ion chambers.

Measurement possibilities using an electronic portal imaging device

A vital role in the quality control of radiotherapy is the use of portal imaging for verifying field size, shape, orientation and patient set-up, Coincidence of treated volume and target volume is imperative. Electronic portal imaging devices are effective at providing this verification, However, these devices are versatile enough to be used in other ways pertinent to the delivery of high quality, high precision radiotherapy, This paper examines two such ways: in assessing the reproducibility of a multileaf collimator system, and in determining exit doses in vivo. Configured as a dosemeter, the system shows a linear response with good dynamic range, Its high spatial resolution was used to show that leaf positioning was reproducible to within 0,5 mm for all tested gantry and collimator angles. Our preliminary results from this exit dosimetry technique demonstrate that, under specific conditions, doses can be determined to within 2,5% of that measured using silicon diodes or ion chambers.

Quality control of radiotherapy during pelvic irradiation

For 20 patients undergoing pelvic irradiation, various set-up methods were compared for accuracy of field placement. The overall incidence of errors on 294 fields checked was lower ( p < 0.001) than that in a previous study. A standard deviation of 1.5 mm for lateral placement accuracy was ahtained.

Elapsed treatment days—A critical item for radiotherapy quality control review in head and neck trials: RTOG report

For all randomized trials since 1978, the Radiation Therapy Oncology Group has required the study chairman for radiation therapy to review the treatment given to each patient. The chairman scores the compliance of the treatment borders, total dose, fraction, and total elapsed time relative to the protocol prescription at the primary site, regional nodes, and any critical structure. The individual parameters are then considered together to derive an “overall” treatment score. For two RTOG head and neck studies in patients with moderately and very advanced carcinomas, the “overall” treatment was classified as unacceptable if the treatment at primary was scored unacceptable with respect to dose, fractionation, and field borders. However, prolonged elapsed treatment was not included. Analysis of these studies with 426 evaluable patients was performed to assess the relationship of unacceptable “overall” treatment compliance with outcome. Patients with prolonged treatment elapsed days (14 days beyond the protocol prescription) exhibited significantly poorer loco-regional control (13% vs. 27% at 3 years with p = .007) and absolute survival (13% vs. 26% at 3 years with p = .01). As a result, the criteria for unacceptable “overall” treatment were revised to include prolonged elapsed treatment days. Further multivariate analyses showed the revised criteria identified patients with significantly poorer loco-regional control and absolute survival even after adjusting for other prognostic factors.

Evaluation of a commercial diode monitor for mailed quality control of therapy units

A commercial diode dosimeter was evaluated for use in a mailed radiotherapy quality control package. The quality control package contained the commercial diode dosimeter and four thermoluminescent dosimeters to measure the given dose, and it also contained a photographic film to measure the light/radiation field coincidence. The film also served as a backup dosimeter. Twenty small Midwestern hospitals participated in field measurements; approximately half of the hospitals had a consulting physicist and the others had one full-time physicist. Each hospital was asked to deliver 1.5 Gy (150 rads) to the device, which was returned to our laboratory for evaluation. Reliable results were obtained from three measurements at each hospital at about 3-month intervals. The diode dosimeter was more precise than thermoluminescent dosimeters or film.

Quality control in radiotherapy: The reduction of field placement errors

A ‘blind’ study using treatment verification films has been performed on two series of patients to assess the accuracy of placement of complex infradiaphragmatic fields planned to include para-aortic nodes. Sequential verification films (VF) for each field on all patients studied were compared to determine variations in field position relative to the anatomy, especially lymph nodes, and the simulator plan. Nodes included in the plan but partially or completely missed by one or more treatments were identified, as were the error types involved. In series I, 21% of 157 VF showed a nodal miss, and after changes in practice designed to minimize the error types responsible for those, the figure was reduced in series II to 5.5% of 194 VF. In series II a 50% reduction in magnitude of the average systematic lateral shift and rotation of posterior fields is attributed mainly to the discontinuation of the practice of treating posterior fields through the couch. Apart from a prescribed width of <9 cm, three quantitative key factors were derived: >6 mm lateral shift, >7 mm field narrowing, 2 degree or more rotation of fields. The correction of these errors if identified on verification films, should eliminate the subsequent occurrence of node misses. The value of routine clinical treatment verification films at the start of treatment to identify and correct systematic errors is emphasized, as is the importance of precise and standardized technical practice.

The value of treatment portal films in radiotherapy for bronchial carcinoma

In 1985, thoracic irradiation was performed in 74 patients with lung cancer in our centre. For a total of 182 field set-ups, 142 portal films were taken and compared to the simulator radiograph. In 46 cases (33%), the portal films were at variance with the simulator film. Minimal differences, demanding no further correction were seen in four cases (2.9%). There were no errors due to misplacement of a transparent plastic plate on which the field (with central axis and blocks) is outlined. A slight patient malposition was found on eight portal films (5.6%). In 5.6%, the centre of the plastic plate did not match the field centre. Wrong block position was the most common type of error: 26 cases (18.3%). In 18 of these, the marking of treatment field edges and blocks on the plastic plate was incorrect. The tumour was even partially shielded in 16 of these. In the other eight cases, block placement was erroneous at treatment set-up. Even in the presence of careful simulation and field set-up, portal film remains an indispensable step in the quality control of radiotherapy for lung cancer.