Methods for improving the accuracy of glutamine lyoluminescence dosimetry

The dependence of the lyoluminescence (LL) yield on the mass of dissolved glutamine, the sample irradiation temperature and solvent temperature, and the storage time both before and after heat treatment (HT) was investigated. Results are presented for measurements in both pure water and in terbium(III) nitrate solutions. Terbium(III) ions enhance glutamine's LL yield. HT's of 114°C for 5 and 21 h were tried. Irradiation of glutamine produces two alkyl free radicals; one named Ṙ₁, more stable than Ṙ₁. It is believed that Ṙ₁ reduces the LL yield. The gradual decay of Ṙ₁ during storage of untreated samples results in an increased LL yield. The rate of this increase depends on dose. Heat treatment removes the dependence of the yield on storage time and increases the yield (by a factor of approximately 2). It is suggested that heat treatment reduces Ṙ₁ to the same final concentration in all samples given the same dose. The shorter heat treatment which resulted in a variation of 4% between samples stored for up to 87 days before HT and up to 86 days after HT, gave better results than the longer treatment. The yield of treated samples increases linearly with irradiation temperature (between 14 and 39°C) by 0.63 (±0.03)% and 0.65 (±0.04)% per °C above 22°C for LL readings taken in pure water and terbium nitrate solutions respectively. No such correlation was found for untreated samples. Limiting the range of (a) the mass of glutamine dissolved to ±0.5 mg and (b) the temperature of the solvent to ±0.1 °C reduces the variation in yield due to each factor to less than 0.4% using either water or terbium nitrate as the solvent.     

Radiotherapy skin care: A survey of practice in the UK

AimThe primary objective of the survey was to evaluate clinical skin care practice in radiotherapy departments across the United Kingdom.Methods and sampleA questionnaire containing sixty-one questions grouped into eight themed sections was developed and a link to an on-line survey, using the Survey Monkey? tool, was e-mailed to all radiotherapy department managers in the United Kingdom (N = 67). Each recipient was invited to provide one response per department.Key resultsFifty-four departments responded within the allocated timeframe giving a final response rate of 81%. Products and their use for skin conditions varied and some outdated and unfounded practices were still being used which did not always reflect the current evidence base. The amount of data routinely collected on skin toxicity was limited making it difficult to quantify the extent of skin morbidity following radiotherapy.ConclusionThe survey demonstrated variability in skin care practice in radiotherapy departments across the UK, with limited practice based on evidence or on skin toxicity measurement and monitoring.     

An update survey of UK in vivo radiotherapy dosimetry practice

A questionnaire was distributed in 2004 to 59 radiotherapy physics departments in the UK to determine whether in vivo dosimetry practice had changed since a similar survey conducted 10 years earlier. The number of centres carrying out central axis dosimetry had increased slightly from 17 centres in 1994 to 22 centres in 2004, with a diode alone being the most commonly used detector. Twice as many centres (43) carried out critical organ dosimetry compared with those carrying out central axis measurements, and this number had also increased slightly above the 1994 value (38). A diode was used by most centres carrying out central axis dosimetry and by about 50% of centres carrying out critical organ dosimetry. The action level adopted by each centre for central axis measurements varied from >+/-3% to >+/-10% difference between the measured and the prescribed dose, with >+/-5% being the most frequent value. It was concluded that there had been little change in in vivo dosimetry practice during the time between the two surveys, and that guidance on the method and applications for in vivo dosimetry is required before recent recommendations for its widespread adoption for routine use can be satisfied.     

International dosimetry: an evaluation of treatment planning in clinical trials.

A tissue-equivalent phantom containing thermoluminescent dosimeters was mailed in succession to Mount Vernon Hospital, Northwood, Middlesex, England, to Groote Schuur Hospital, Capetown, South Africa, and to Winnipeg General Hospital, Winnipeg, Canada, to determine the accuracy and consistency in treatment for carcinoma of the cervix under hyperbaric oxygen conditions. (Protocol of the Medical Research Council's Working Party on Radiotherapy and Hyperbaric Oxygen.) The data were analysed by the Radiological Physics Center, Houston, Texas, and substantiate uniformity at and between the participating institutions.     

Radiotherapy treatment of non-melanoma skin cancer: a survey of current UK practice and commentary

Objective:

In the ongoing absence of available trial data, a national survey was carried out to provide details on radiotherapy treatment strategy for non-melanoma skin cancer (NMSC).

Methods:

A survey of clinical oncologists treating NMSC was performed. The respondents were asked for basic information on workload as well as a proposed treatment strategy for various clinical scenarios for patients of varying fitness.

Results:

A total of 43 completed and 20 partially completed surveys were received. There was a wide variation in the workload and additional disease sites that respondents had responsibility for. Kilovoltage radiotherapy was available to 81% of responders. The respondents'' approach was affected by the fitness of patients, with longer fractionation regimes proposed for younger, fitter patients and shorter or non-standard fractionations more likely for the infirm elderly. Four daily fractionation regimes (18–20 Gy in 1 fraction, 35 Gy in 5 fractions, 45 Gy in 10 fractions and 55 Gy in 20 fractions) were most commonly suggested. There was a large degree of variation in non-standard fractions proposed with significant potential differences in radiobiological effect. Concern over the use of kilovoltage photons on skin over cartilage was apparent, as was a reluctance to use radiotherapy in areas of increased risk of poor wound healing.

Conclusion:

The survey results largely showed practice to be in line with available published evidence. The variation seen in some areas, such as non-standard fractionation, would benefit from the publication of local outcomes to achieve a more consistent approach.

Advances in knowledge:

This study provides information on national practices and identifies variations, particularly within widespread use of non-standard fractionation.Non-melanoma skin cancer (NMSC) is the most common malignancy in the UK. In 2010, around 100,000 people were diagnosed with NMSC, and there were 585 related deaths in 2011.¹ The vast majority of these lesions are basal cell carcinomas (BCCs) or, less commonly, squamous cell carcinomas (SCCs). Various treatment modalities can be utilized to manage this condition, with a potential for excellent local control and cosmesis, including topical therapies, surgical excision, electrocautery, cryotherapy and radiotherapy. The choice of treatment approach is influenced by the stage and location of disease, patient fitness and preference. For patients who are not fit enough to be considered for surgery or for disease in locations where excision would be cosmetically undesirable, the use of radiotherapy is commonly recommended.Various methods of radiotherapy delivery are available, including electron, kilovoltage and megavoltage external beam radiotherapy as well as brachytherapy, although there is variable access to these methods between centres in the UK. A lack of prospective trial data to guide treatment has led to the development of local practice regarding dose fractionation schedules, and it is unclear how much variation currently exists nationally. In the absence of likely forthcoming trials, there is little impetus for variable practice to change.To potentially streamline clinical practice, details on the most commonly used strategies employed in various clinical scenarios would be of interest as a basis for harmonizing dose/fractionation schedules.     

Publications on clinical trials with X-ray contrast media: differences in quality between journals and decades

The objective of the present study was to investigate the quality of clinical trial publications on X-ray contrast media by use of a simple criteria list with 11 items. The publication quality in the 1960s, 1970s and 1980s and in five radiological journals was compared. One hundred and three articles retrieved from the literature and published in Br J Radiol (British), Acta Radiol (Scandinavian), Radiology (American), R?Fo (German) and in Ann Radiol (French) were finally included. The adapted method seemed to be suitable for roughly assessing the quality of contrast medium publications. The present reporting standard has increased considerably since the 1960s, however a higher standard is still needed. Although the limited material gathered in our investigation does not allow unequivocal statements, the results indicate that the reporting standard of the 1980s in the selected American, British and Scandinavian radiological journals was somewhat better than in the German journal and better than in the French journal. Use of the present or other assessment methods is one tool to improve the reporting standard.     

Accurate dosimetry: an essential step towards good clinical practice in nuclear medicine

In nuclear medicine, an increasing number of radiolabelled agents are under investigation for future use in diagnostic imaging and for applications in radionuclide therapy. All these studies require large amounts of human data to allow for statistical comparisons with existing and well established diagnostic or therapeutic methodologies. In the framework of a good clinical practice environment, clinical trials should be carried out according to international guidelines and regulations as described in the Declaration of Helsinki. Studies involving ionizing radiation, as is the case in nuclear medicine, require special consideration to comply with the ALARA (as low as reasonably achievable) principle. Special publications of the International Commission of Radiological Protection and the World Health Organization deal with this topic in medical research. From the legislation point of view, the 97/43/EURATOM Directive represents the reference to clinical research using ionizing radiation within the European Union. In order to keep the radiation dose of (healthy) volunteers as low as possible, predictive dosimetry studies based on in-vivo animal biokinetics are essential. On the other hand, patients included in dose-escalation radionuclide therapy trials should be monitored individually with respect to dosimetry of the tumour and the critical organs. In this paper the importance and methodology of contemporary patient dosimetry in diagnostic and therapeutic nuclear medicine research are reviewed. It is concluded that reliable dosimetry is essential in performing scientific clinical studies according to the principle of good clinical practice.     

Radioimmunotherapy of B-cell non-Hodgkin's lymphoma: from clinical trials to clinical practice.

Radioimmunotherapy (RIT) is a new treatment modality for B-cell non-Hodgkin's lymphoma (NHL). Recent clinical trials have clearly established its efficacy in NHL patients refractory to standard chemotherapy or immunotherapy with the widely used unconjugated rituximab monoclonal antibody (mAb). The Food and Drug Administration has approved (90)Y-ibritumomab tiuxetan anti-B-cell NHL mAb as the first commercially available radiolabeled antibody for cancer therapy. This comes only a few years after the introduction of rituximab into clinical practice as the first unconjugated antibody for cancer treatment, underscoring the success of both immunotherapy and RIT in the treatment of NHL. With the approval of (90)Y-ibritumomab tiuxetan, and based on the results of numerous clinical trials with radiolabeled anti-B-cell NHL mAbs, RIT promises to become integral to nuclear medicine practice. In this article, the basic concepts of RIT are reviewed with important milestones in its development for B-cell NHL treatment and particular emphasis on phase II and III clinical trials establishing its efficacy in clearly defined patient populations. Finally, the prospects for the expected widespread clinical use of RIT in the management of B-cell NHL, alone or in combination with other more established therapies, are discussed. This article provides both investigative and clinical nuclear medicine physicians with a better understanding of RIT capabilities and limitations in B-cell NHL and their role as consultants in the care of NHL patients.     

Factors affecting accuracy of S values and determination of time-integrated activity in clinical Lu-177 dosimetry

Annals of Nuclear Medicine - In any radiotherapy, the absorbed dose needs to be estimated based on two factors, the time-integrated activity of the administered radiopharmaceutical and the...