Advice

Clinical and technical evidence

Clinical and technical evidence

A literature search was carried out for this briefing in accordance with the interim process and methods statement. This briefing includes the most relevant or best available published evidence relating to the clinical effectiveness of the technology. Further information about how the evidence for this briefing was selected is available on request by contacting mibs@nice.org.uk.

Published evidence

This briefing summarises 4 studies, including 228 patients having over 2,000 individual radiotherapy treatment fractions. Table 1 summarises the clinical evidence as well as its strengths and limitations.

Overall assessment of the evidence

The evidence for AlignRT is limited to small, non-comparative, observational studies. Three of the studies were done in the US and 1 was done in Europe, so their generalisability to NHS practice is unclear.

The evidence shows that AlignRT plus controlled breath holding results in less inadvertent irradiation than free breathing. The effectiveness of this method strongly relies on the portion of the heart in the radiotherapy field. In 1 study (Zagar et al. 2015), no portion of the heart was left within the primary radiotherapy field and at 6 months, none of the patients assessed had post-radiotherapy cardiac perfusion. The study authors noted that in previous publications using similar technologies, rates of post-radiotherapy cardiac perfusion ranged from 1% and 50%, and the proportion of the left ventricle still in the radiotherapy field was between 1% and 10%. The study by Ferrara (2010) alluded to savings in radiotherapy suite time from the use of AlignRT, by reducing the time needed for other imaging procedures.

Table 1 Summary of selected studies

Gierga et al. (2012)

Study size, design and location

Observational study of 20 patients with breast cancer and unfavourable cardiac anatomy diagnosed using a CT scan (443 radiotherapy treatments; 2,398 individual breath holds). US study.

Intervention and comparator(s)

Patients had an initial planning CT scan and weekly MV imaging to guide the radiation treatment and accurately target the breast tissue. The radiotherapy was delivered in small fractions over several days and weeks. Patients also had a daily surface image scan with AlignRT. No comparator; study used AlignRT to assess patient movement using the voluntary breath-hold technique to avoid cardiac radiation exposure.

Key outcomes

The study showed that 22% of patients were outside of a 5 mm movement tolerance during the breath hold and these correlated with the volume of breast tissue.

Strengths and limitations

This study included a relatively small number of patients but involved numerous individual treatment sessions. It shows that daily surface imaging can be incorporated into radiotherapy workflows and assist in accurate patient alignment. The time taken in using this technique was not recorded.

Zagar et al. (2017)

Study size, design and location

Prospective observational study on DIBH to avoid cardiac radiation exposure assessed using AlignRT surface imaging. 20 patients (over 400 separate radiation treatment fractions) with left-sided breast cancer already planned to use DIBH. US study.

Intervention and comparator

No comparator. AlignRT was used at the start of each treatment to check alignment with the planning images. Patients had SPECT of the heart before radiotherapy and at 6-month follow-up to assess cardiac perfusion.

Key outcomes

No change in cardiac perfusion was detected at 6-month follow-up.

Strengths and limitations

This is a small study with no comparator group. It shows that AlignRT plus controlled breath holding during radiotherapy may minimise cardiac perfusion. It is uncertain if the surrogate marker for heart injury used in this study at 6 months would appropriately identify patients at risk of heart injury over the long term.

Tanguturi et al. (2015)

Study size, design and location

150 patients with left breast cancer prospectively enrolled in a US registry.

Intervention and comparator(s)

Patients had radiotherapy using either FB or DIBH, depending on their clinical condition. All DIBH patients had their position monitored by AlignRT.

Key outcomes

38 patients used FB and 110 used DIBH. The time taken for treatment was not statistically significantly different but there was more variability in the DIBH treatment times. 107 DIBH patients had >20 cGy lower mean heart dose of radiation. Paired comparisons with FB patients (paired based on RT plans) showed statistically significantly lower heart and lung radiation doses. Higher rates of mean heart dose were associated with younger patients of larger BMI and larger lung volume.

Strengths and limitations

This is a relatively large study but had no control group. It shows that a breath-holding technique, with AlignRT-controlled patient positioning, resulted in lower inadvertent heart and lung radiation exposure compared with free breathing, but with similar treatment times.

Ferrara et al. (2010)

Study size, design and location

38 patients with breast cancer as 1 arm of a randomised study on errors in patient positioning during radiotherapy. Italian study.

Intervention and comparator(s)

No comparator. AlignRT was used before treatment to measure error between a reference patient CT position and actual position.

Key outcomes

Mean setup time was 7.9 minutes (range 3 to 16) and there was no additional time needed for AlignRT measurements. 657 images were collected. Patient positioning and setup with AlignRT was consistent with usual positioning methods.

Strengths and limitations

This was a small study reported only as an abstract, but it shows that no extra time is needed to use AlignRT during radiotherapy treatment.

Abbreviations: DIBH, deep-inspiration breath holding; FB, free breathing; MV, megavoltage; SPECT, single-photon emission computed tomography.

Recent and ongoing studies