Verification films: a study of the daily and weekly reproducibility of breast patient set-up in the START trial

Determination of geometric accuracy of radiotherapy fields by port film and DRR using Matlab graphical user interface

The purpose of this study is to determine and verify the exact location of radiation therapy fields by using port-film and digital reconstruction radiograph (DRR) as a low-cost tool. Initially, an appropriate algorithm was written for the application of port film in the megavoltage beam irradiation. Detectable contrast was created for the image and then by using appropriate markers and developed written program by MATLAB as DRrPortRegistartion. Semi-automatic and automatic registration between port-film and DRR images were performed for pelvic and chest phantoms. Then, results were compared with electronic portal imaging device (EPID) images in similar conditions. By using this software, DRR and port film as treatment verification tools, the precision of treatment verification and the accuracy of radiation therapy fields were achieved in the extent of the millimeter. Validation results with EPID demonstrated that the mean absolute average error in angle is equal to 0.59 degrees, 1.70 mm in the X-direction, and 2.42 mm in the Y-direction. The results of this study illustrated that using this software and suitable low-cost hardware in the machines without EPID can increase the precision of treatment verification to the millimeter and it can be introduced as a suitable alternative for EPID in centers for increasing treatment accuracy. Graphical abstract ᅟ.

Practice-changing radiation therapy trials for the treatment of cancer: where are we 150 years after the birth of Marie Curie?

As we mark 150 years since the birth of Marie Curie, we reflect on the global advances made in radiation oncology and the current status of radiation therapy (RT) research. Large-scale international RT clinical trials have been fundamental in driving evidence-based change and have served to improve cancer management and to reduce side effects. Radiation therapy trials have also improved practice by increasing quality assurance and consistency in treatment protocols across multiple centres. This review summarises some of the key RT practice-changing clinical trials over the last two decades, in four common cancer sites for which RT is a crucial component of curative treatment: breast, lung, urological and lower gastro-intestinal cancer. We highlight the global inequality in access to RT, and the work of international organisations, such as the International Atomic Energy Agency (IAEA), the European SocieTy for Radiotherapy and Oncology (ESTRO), and the United Kingdom National Cancer Research Institute Clinical and Translational Radiotherapy Research Working Group (CTRad), that aim to improve access to RT and facilitate radiation research. We discuss some emerging RT technologies including proton beam therapy and magnetic resonance linear accelerators and predict likely future directions in clinical RT research.

Impact of the frequency of online verifications on the patient set-up accuracy and set-up margins

Purpose

The purpose of the study was to evaluate the patient set-up error of different anatomical sites, to estimate the effect of different frequencies of online verifications on the patient set-up accuracy, and to calculate margins to accommodate for the patient set-up error (ICRU set-up margin, SM).

Methods and materials

Alignment data of 148 patients treated with inversed planned intensity modulated radiotherapy (IMRT) or three-dimensional conformal radiotherapy (3D-CRT) of the head and neck (n = 31), chest (n = 72), abdomen (n = 15), and pelvis (n = 30) were evaluated. The patient set-up accuracy was assessed using orthogonal megavoltage electronic portal images of 2328 fractions of 173 planning target volumes (PTV). In 25 patients, two PTVs were analyzed where the PTVs were located in different anatomical sites and treated in two different radiotherapy courses. The patient set-up error and the corresponding SM were retrospectively determined assuming no online verification, online verification once a week and online verification every other day.

Results

The SM could be effectively reduced with increasing frequency of online verifications. However, a significant frequency of relevant set-up errors remained even after online verification every other day. For example, residual set-up errors larger than 5 mm were observed on average in 18% to 27% of all fractions of patients treated in the chest, abdomen and pelvis, and in 10% of fractions of patients treated in the head and neck after online verification every other day.

Conclusion

In patients where high set-up accuracy is desired, daily online verification is highly recommended.

Correction of systematic set-up error in breast and head and neck irradiation through a no-action level (NAL) protocol

PURPOSE

To quantify systematic and random patient set-up errors in breast and head and neck conventional irradiation and to evaluate a no-action level (NAL) protocol for systematic set-up error off-line correction in head and neck cancer and breast cancer patients.

MATERIAL AND METHODS

Verification electronic portal images of orthogonal set-up fields were obtained daily for the initial four consecutive fractions for 20 patients treated for breast cancer and for 20 head and neck cancer patients. The calculated systematic error was used to shift the isocentre accordingly on the fifth treatment day. From then until the end of the treatment course, pair orthogonal portal images of set-up fields were obtained weekly. To assess the impact of the protocol, pre- and post-correction systematic errors were compared and PTV margins were estimated before and after correction using published margin recipes.

RESULTS

Population systematic set-up error decreased in the breast cancer patient group after the implementation of NAL protocol from 4.0 to 1.7 mm on the x-axis, from 4.7 to 2.1 mm on the y-axis and from 2.8 to 0.9 mm on the z axis. The percentage of patients with individual systematic set-up error reduction was 80%, 90% and 80% on the x-, y and z-axes respectively. Population systematic set-up error decreased also in the head and neck cancer patient group from 2.3 to 1.1 mm on the x-axis, from 1.6 to 1.4 mm on the y-axis and from 1.7 to 0.7 mm on the z-axis. The percentage of patients with individual systematic set-up error reduction was 70%, 65% and 85% on the x-, y- and z-axes respectively. Margin reduction achievable with NAL protocol implementation on the x-, y- and z-axes was 6.3, 7.2 and 4.8 mm for breast cancer patients and 3.3, 0.6 and 2.8 mm for head and neck cancer patients.

CONCLUSION

NAL off-line protocol is useful for systematic set-up error correction and PTV margin reduction in conventional breast and head and neck irradiation.

Radiotherapy research activity and radiographer involvement in the UK

In the UK, radiotherapy research is being conducted at national and international levels which include multi-centre clinical trials. Local initiatives and trials are also ongoing where work is being performed to develop techniques or protocols for new technologies and service development. Active participation within these studies is now leading to a culture change with radiographers (radiation therapists) becoming an integral part of the research process. There are currently 70 radiographers in the UK participating in research. This accounts for 2.5% of the UK profession. With the extension of role diversification, research radiographers are undertaking many new roles; however, there is still scope for further development. The therapists’ role in working within this research environment is to ensure improved standards of care focussed on evidence-based practice.

Dosimetry and field matching for radiotherapy to the breast and supraclavicular fossa

PURPOSE

Early breast cancer radiotherapy aims for local disease control and reduced recurrence. Treatment is directed to breast or chest wall alone using tangential fields, or includes regional lymph nodes with a separate anterior field. The complex geometry of this region necessitates matching adjacent radiation fields in three-dimensions. Potential exists for overdosage or underdosage and cosmetic results may be compromised if fields are not accurately aligned.

METHODS AND MATERIALS

A study of dosimetry across the match line region using different techniques, as reported in the multicentre START Trial Quality Assurance programme, was undertaken. A custom-made anthropomorphic phantom assessed dose distribution in three-dimensions using film dosimetry.

RESULTS

Methods with varying degrees of complexity were employed for field matching. Techniques combined half beam blocking and machine rotations to achieve geometric alignment. Asymmetric beam matching allowed use of a single isocentre technique. Where field matching was not undertaken a gap between tangential and nodal fields was employed. Results demonstrated differences between techniques and variations for similar techniques in different centres. Geometric alignment techniques produced more homogenous dose distributions in the match region than gap techniques or those techniques not correcting for field divergence.

CONCLUSIONS

Field matching techniques during the START trial varied between centres. Film dosimetry used in conjunction with a breast-shaped phantom provided relative dose information. The study highlighted difficulties in matching treatment fields to achieve homogenous dose distribution through the region of the match plane and the degree of inhomogeneity as a consequence of a gap between treatment fields.

The UK Standardisation of Breast Radiotherapy (START) Trial B of radiotherapy hypofractionation for treatment of early breast cancer: a randomised trial

BACKGROUND

The international standard radiotherapy schedule for early breast cancer delivers 50 Gy in 25 fractions of 2.0 Gy over 5 weeks, but there is a long history of non-standard regimens delivering a lower total dose using fewer, larger fractions (hypofractionation). We aimed to test the benefits of radiotherapy schedules using fraction sizes larger than 2.0 Gy in terms of local-regional tumour control, normal tissue responses, quality of life, and economic consequences in women prescribed post-operative radiotherapy.

METHODS

Between 1999 and 2001, 2215 women with early breast cancer (pT1-3a pN0-1 M0) at 23 centres in the UK were randomly assigned after primary surgery to receive 50 Gy in 25 fractions of 2.0 Gy over 5 weeks or 40 Gy in 15 fractions of 2.67 Gy over 3 weeks. Women were eligible for the trial if they were aged over 18 years, did not have an immediate reconstruction, and were available for follow-up. Randomisation method was computer generated and was not blinded. The protocol-specified principal endpoints were local-regional tumour relapse, defined as reappearance of cancer at irradiated sites, late normal tissue effects, and quality of life. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN59368779.

FINDINGS

1105 women were assigned to the 50 Gy group and 1110 to the 40 Gy group. After a median follow up of 6.0 years (IQR 5.0-6.2) the rate of local-regional tumour relapse at 5 years was 2.2% (95% CI 1.3-3.1) in the 40 Gy group and 3.3% (95% CI 2.2 to 4.5) in the 50 Gy group, representing an absolute difference of -0.7% (95% CI -1.7% to 0.9%)--ie, the absolute difference in local-regional relapse could be up to 1.7% better and at most 1% worse after 40 Gy than after 50 Gy. Photographic and patient self-assessments indicated lower rates of late adverse effects after 40 Gy than after 50 Gy.

INTERPRETATION

A radiation schedule delivering 40 Gy in 15 fractions seems to offer rates of local-regional tumour relapse and late adverse effects at least as favourable as the standard schedule of 50 Gy in 25 fractions.

The UK Standardisation of Breast Radiotherapy (START) Trial A of radiotherapy hypofractionation for treatment of early breast cancer: a randomised trial

Background

The international standard radiotherapy schedule for breast cancer treatment delivers a high total dose in 25 small daily doses (fractions). However, a lower total dose delivered in fewer, larger fractions (hypofractionation) is hypothesised to be at least as safe and effective as the standard treatment. We tested two dose levels of a 13-fraction schedule against the standard regimen with the aim of measuring the sensitivity of normal and malignant tissues to fraction size.

Methods

Between 1998 and 2002, 2236 women with early breast cancer (pT1-3a pN0-1 M0) at 17 centres in the UK were randomly assigned after primary surgery to receive 50 Gy in 25 fractions of 2·0 Gy versus 41·6 Gy or 39 Gy in 13 fractions of 3·2 Gy or 3·0 Gy over 5 weeks. Women were eligible if they were aged over 18 years, did not have an immediate surgical reconstruction, and were available for follow-up. Randomisation method was computer generated and was not blinded. The protocol-specified principal endpoints were local-regional tumour relapse, defined as reappearance of cancer at irradiated sites, late normal tissue effects, and quality of life. Analysis was by intention to treat. This study is registered as an International Standard Randomised Controlled Trial, number ISRCTN59368779.

Findings

749 women were assigned to the 50 Gy group, 750 to the 41·6 Gy group, and 737 to the 39 Gy group. After a median follow up of 5·1 years (IQR 4·4–6·0) the rate of local-regional tumour relapse at 5 years was 3·6% (95% CI 2·2–5·1) after 50 Gy, 3·5% (95% CI 2·1–4·3) after 41·6 Gy, and 5·2% (95% CI 3·5–6·9) after 39 Gy. The estimated absolute differences in 5-year local-regional relapse rates compared with 50 Gy were 0·2% (95% CI −1·3% to 2·6%) after 41·6 Gy and 0·9% (95% CI −0·8% to 3·7%) after 39 Gy. Photographic and patient self-assessments suggested lower rates of late adverse effects after 39 Gy than with 50 Gy, with an HR for late change in breast appearance (photographic) of 0·69 (95% CI 0·52–0·91, p=0·01). From a planned meta-analysis with the pilot trial, the adjusted estimates of α/β value for tumour control was 4·6 Gy (95% CI 1·1–8·1) and for late change in breast appearance (photographic) was 3·4 Gy (95% CI 2·3–4·5).

Interpretation

The data are consistent with the hypothesis that breast cancer and the dose-limiting normal tissues respond similarly to change in radiotherapy fraction size. 41·6 Gy in 13 fractions was similar to the control regimen of 50 Gy in 25 fractions in terms of local-regional tumour control and late normal tissue effects, a result consistent with the result of START Trial B. A lower total dose in a smaller number of fractions could offer similar rates of tumour control and normal tissue damage as the international standard fractionation schedule of 50 Gy in 25 fractions.

Radiation therapy using a simultaneously integrated boost for early-stage breast cancer

Evaluation of: van der Laan HP, Dolsma WV, Maduro JH et al.: Three-dimensional conformal simultaneously integrated boost technique for breast-conserving therapy. Int. J. Radiat. Oncol. Biol. Phys. 68(4), 1018–1023 (2007). Radiotherapy of 25 daily fractions of 2 Gy after breast-conserving surgery is effective in reducing the risk of a local recurrence. An extra boost dose of eight daily fractions of 2 Gy reduces this risk even further by a factor of 1.7. However, the extended treatment time is not patient friendly and is more labor intensive. With new, advanced equipment, it is now possible to use a so-called simultaneous integrated boost (SIB) technique to prevent these downsides. With this technique, the boost dose is integrated into the standard dose fractions, thus reducing the number of times a patient has to be irradiated. However, the initial implementation of this technique is very labor intensive and requires profound knowledge of the radiotherapy treatment planning system and treatment unit. In their article, van der Laan and colleagues present an SIB technique which is easier to implement than a sophisticated (inversely planned) SIB technique. Moreover, they are the first authors to present data on acute skin toxicity using this technique and fractionation schedule. Their work contributes significantly to the efforts of clinical physicists, radiation oncologists and radiation therapists worldwide to improve breast cancer patient care by the safe implementation of new, advanced radiotherapy technology. However, one has to realize that implementing such a technique still requires accurate knowledge of the target volume delineation and patient set-up accuracy in each institution. Also, boost volume changes may occur during treatment, which must be taken into account. Data are becoming available on this, and clinical trials investigating even higher boost doses or more conformal treatment techniques are being conducted.

Radiotherapy Treatment Verification in the UK: An Audit of Practice in 2004

AIMS

To audit current practice related to treatment verification undertaken in radiotherapy departments throughout the UK.

MATERIALS AND METHODS

A questionnaire was circulated to the radiotherapy service managers of 62 radiotherapy centres in the UK. This looked in detail at the department demographics, imaging equipment, site-specific verification protocols, and training and competency assessment of staff responsible for verification.

RESULTS

The response rate was 48% (30/62). All departments were using megavoltage imaging equipment in routine clinical practice. Twenty-four out of 29 (83%) departments that had electronic portal imaging capability were using image analysis software for verification. Twenty-nine out of 30 (97%) departments had site-specific written verification protocols. Twenty out of 30 (67%) treatment centres audited set-up errors within their department. Forty-three per cent of centres were using simulator image as the reference image of choice across all sites. Electronic portal imaging, alone or in combination with portal film, was being used for verification in 75% of the centres. Fifty-three per cent of centres used off-line correction strategies for measuring set-up errors across all sites. Radiographer-led interventions were primarily in the pelvis.

CONCLUSION

Presently in the UK, verification strategies vary widely at individual treatment sites and between departments. Dedicated departmental verification teams, with input from radiographers, physicists and clinicians, may assist in the effective implementation of evidence-based verification. The inclusion of comprehensive verification protocols within multicentre radiotherapy trials encourages standardisation across treatment centres.