Practical aspects of implementation of helical tomotherapy for intensity-modulated and image-guided radiotherapy.
ABSTRACT Image-guided radiotherapy (IGRT) and intensity-modulated radiotherapy (IMRT) represent two important technical developments that will probably improve patient outcome. Helical tomotherapy, provided by the TomoTherapy HiArt system, provides an elegant integrated solution providing both technologies, although others are available. Here we report our experience of clinical implementation of daily online IGRT and IMRT using helical tomotherapy.
Methods were needed to select patients who would probably benefit. Machine-specific commissioning, a quality assurance programme and patient-specific delivery quality assurance were also needed. The planning target volume dose was prescribed as the median dose, with the added criterion that the 95% isodose should cover 99% of the target volume. Although back-up plans, for delivery on conventional linear accelerators, were initially prepared, this practice was abandoned because they were used very rarely.
In the first 12 months, 114 patients were accepted for treatment, and 3343 fractions delivered. New starts averaged 2.6 per week, with an average of 17.5 fractions treated per day, and the total number capped at 22. This has subsequently been raised to 24. Of the first 100 patients, 96 were treated with radical intent. Five were considered to have been untreatable on our standard equipment. IGRT is radiographer led and all patients were imaged daily, with positional correction made before treatment, using an action level of 1mm. A formal training programme was developed and implemented before installation. The in-room time fell significantly during the year, reflecting increasing experience and a software upgrade. More recently, after a couch upgrade in April 2009, the mean in-room time fell to 18.6 min.
Successful implementation of tomotherapy was the result of careful planning and effective teamwork. Treatment, including daily image guidance, positional correction and intensity-modulated delivery, is fast and efficient, and can be integrated into routine service. This should encourage the adoption of these technologies.
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ABSTRACT: There is much evidence for the detrimental effect on tumour control of missed treatment days during radiotherapy, amounting for example to approximately a 1.6% absolute decrease in local control probability per day of treatment prolongation in the case of head and neck squamous cell cancer. Various methods to compensate for missed treatment days are compared quantitatively in this article, using the linear-quadratic formalism. The overall time and fraction size can be maintained by either treating on weekend days (the preferred way (Method 1a), although with unsocial hours and at extra cost) or using two fractions per day to "catch up' (Method 1b). The latter might incur a small loss of tolerance regarding late reactions, when intervals of 6-8 h are used rather than 24 h, and there may be logistical/scheduling difficulties with larger numbers of patients in some centres when using this method. A second type of strategy retains overall treatment time, and also one fraction per day, but the size of the dose per fraction is increased. For example, this may be done for the same number of "post-gap' days as gap days (Method 2). However, with this method, calculated isoeffect doses regarding late reactions indicate a probable decrease in tumour control rate (Method 2a). Otherwise, isoeffective doses regarding tumour control result in an increase in late reactions (Method 2b). In addition, this method is unsuitable for short regimens already using high doses per fraction. To reduce this problem, overall treatment time can also be retained by using fewer fractions, all of greater size in the case of planned gaps (statutory holidays), or larger remaining fractions after unplanned gaps (Method 2c). The problem also with this method is that equivalence for tumour control gives an increase in late reactions. The least satisfactory strategy (Method 3) is to accept the protraction caused by the missed treatment days, and give either the same prescribed number of (slightly larger) fractions or the planned treatment followed by one (or more) extra fraction to compensate for the gap. This would retain the expected local control rate, but there would be an increase in late reactions. An example of this, using average parameter values, is that a 3-day gap (necessitating four extra days to complete treatment with one fraction of 2.4 Gy) might maintain a 70% local control rate for glottic carcinoma, but severe reactions might rise from 1% to 4% and minor/moderate reactions from 37% to 50%. In this example, the inclusion of an extra weekend would increase the required extra dose and hence may further increase the morbidity rates. A final point is that the effect of treatment interruptions for an individual patient is expected to be greater than that for a group of patients because of interpatient heterogeneity tending to flatten dose-response curves. Calculations show that the above value of 1.6% loss of local control per day for a group of patients may reflect values for individual patients that range around a median value of as much as 5% per day, so stressing further the importance of gaps in treatment. It is concluded that, wherever possible, treatment days should not be missed. If they are missed, it is important to compensate for them, preferably by one of the first of the above methods (1a or 1b), in order to keep as close as possible to the original/standard prescription in terms of total dose, dose per fraction and overall time.Clinical Oncology 02/1996; 8(5):297-307. · 2.86 Impact Factor
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ABSTRACT: BackgroundRadical radiotherapy is commonly used to treat localised prostate cancer. Late chronic side-effects limit the dose that can be given, and may be linked to the volume of normal tissues irradiated. Conformal radiotherapy allows a smaller amount of rectum and bladder to be treated, by shaping the high-dose volume to the prostate. We assessed the ability of this new technology to lessen the risk of radiation-related effects in a randomised controlled trial of conformal versus conventional radiotherapy.MethodsWe recruited men with prostate cancer for treatment with a standard dose of 64 Gy in daily 2 Gy fractions. The men were randomly assigned conformal or conventional radiotherapy treatment. The primary endpoint was the development of late radiation complications (>3 months after treatment) measured with the Radiation Therapy and Oncology Group (RTOG) score. Indicators of disease (cancer) control were also recorded.FindingsIn the 225 men treated, significantly fewer men developed radiation-induced proctitis and bleeding in the conformal group than in the conventional group (37 vs 56% ≥RTOG grade 1, p=0·004; 5 vs 15% ≥RTOG grade 2, p=0·01). There were no differences between groups in bladder function after treatment (53 vs 59% ≥grade 1, p=0·34; 20 vs 23% ≥grade 2, p=0·61). After median follow-up of 3·6 years there was no significant difference between groups in local tumour control (conformal 78% [95% CI 66–86], conventional 83% [69–90]).InterpretationConformal techniques significantly lowered the risk of late radiation-induced proctitis after radiotherapy for prostate cancer. Widespread introduction of these radiotherapy treatment methods is appropriate. Our results are the basis for dose-escalation studies to improve local tumour control.The Lancet 02/1999; · 39.06 Impact Factor
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ABSTRACT: The British government has recently stated its aim of reducing deaths from cancer by a fifth over the next decade, with contributions from prevention, early diagnosis, and better treatments. British cancer cure rates are poorer than those of continental Europe and North America,1 and under—resourcing of radiotherapy services contributes to this.2 The government target could be accomplished by providing adequate radiotherapy facilities to deliver proved clinical treatments.After surgery, radiotherapy is the most effective curative treatment for cancer. Between 30% and 40% of the population will develop cancer, and at least half require radiotherapy at some time in their illness. Of patients having radiotherapy about 60% are treated with curative intent, often in combination with surgery and chemotherapy. Improving the effectiveness of radiotherapy would thus have a substantial impact on cancer cures in the United Kingdom.Provision of adequate radiotherapy facilities would improve the outcome of cancer treatment through three main mechanisms. The first is reduction of the waiting …BMJ 02/2000; 320(7229):198-9. · 14.09 Impact Factor