Categorizing patients on the basis of a semiquantitative approach resulted in significant differences in OS for both the scans before and during therapy. Future work on a larger number of patients is warranted to determine SUV(max) cutoff values which could be used for the early identification of patients with poor treatment outcome or perhaps other therapeutic approaches.

No abstract

Early detection of residual tumour tissue offers the possibility for rapid administration of adjuvant treatment. Single photon emission tomography (SPET) with 3-[123I]iodo-L-alpha-methyl tyrosine (IMT) offers the ability to detect recurrence. The aim of this study was to carry out a prospective evaluation of sequential IMT SPET before and after primary therapy and to determine the best timing for scanning in order to establish the response to treatment. Sixteen consecutive patients with histologically proven head and neck cancer (HNC), who underwent IMT SPET before therapy, within 1 week of therapy, and 1 and 3 months after completion of primary therapy were included. Images were classified, according to clinical evaluation, as indicating a high likelihood (HL), intermediate likelihood (IL) and low likelihood (LL) that residual tumoural tissue was present. The definitive clinicopathological diagnosis and follow-up was considered as the 'gold standard'. Based on the definitive clinicopathological outcome, 10 of 16 patients were diagnosed with evidence of local tumour and six without. Nine of 10 patients with evidence of local tumour presented with an HL IMT SPET image after 3 months, seven of whom were from within the first week. In this group, 1/10 patients was considered clinically HS the first week and eventually 4/10 patients became HL, of which there were three at 3 months. Of the six patients diagnosed without local evidence of tumour, with an average follow-up of 15 months, 6/6 were clinically LL in the first week. Three of six had a consistently LL IMT SPET from within the first week. The three other patients had an HL scan the first week, of which one became IL. It is concluded that IMT SPET assessed the response to primary therapy most accurately 3 months after completion of therapy. An IMT SPET image that indicates a high likelihood of residual tumoural tissue may allow earlier stratification of the patients for secondary treatment. If negative, an IMT SPET can exclude residual tumoural tissue from within the first week after completion of therapy.

No abstract

Background and Purpose: In helical tomotherapy the nature of the optimizing and planning systems allows the delivery of dose on the skin using a build‐up compensating technique (skin‐flash). However, positioning errors or changes in the patient's contour can influence the correct dosage in these regions. This work studies the behavior of skin‐flash regions using phantom and in‐vivo dosimetry. Material and Methods: The dosimetric accuracy of the tomotherapy planning system in skin‐flash regions is checked using film and TLD on phantom. Positioning errors of 5mm to 10mm in both directions are induced and the effect on the skin dose is measured. Further a volume decrease is simulated using bolus material and the results are compared. Results Results show that the tomotherapy planning system can does adequately calculates dose on skin regions within 2SD using TLD‐measurements. Film measurements show drops of dose of 2.8% and 26% for resp. a 5mm and 10mm mispositioning of the phantom towards air and a dose increase of 9% for a 5mm shift towards tissue. These measurements are confirmed by TLD measurements on phantom. A simulated volume reduction shows a similar behavior with a 2.6% and 19.4% drop in dose, measured with TLDs. Conclusion: The tomotherapy system allows adequate planning and delivery of dose using skin flashes. However, exact positioning is crucial to deliver the dose at the exact location and re‐evaluation could be in order when patients will reduce in volume during their treatment.