Permanent prostate brachytherapy: a century of technical evolution.

PURPOSE: To summarise the practical aspects of the development of techniques of interstitial permanent prostate brachytherapy (PPB) implantation. Prostate brachytherapy dates back to Pasteau's publication in 1913 describing the insertion of a radium capsule into the prostatic urethra to treat carcinoma of the prostate. Various implantation methods were employed but with unsatisfactory results until the development of the transrectal ultrasound in the 1980s. The subsequent two-stage Seattle technique allowed for a planned homogenous distribution of radioactive sources throughout the gland resulting in biochemical control comparable to surgical and external beam radiotherapy series. With the advent of advanced computer software and improved imaging, the technique has developed accordingly to a single stage procedure with on-table dosimetric assessment. The principles of targeting dose to the prostate while avoiding surrounding organs at risk remain as relevant today as nearly a century ago. There is an array of techniques to consider for the novice PPB provider. Whether the evolution of PPB techniques will translate into improved biochemical control is yet to be seen.

Using combined x-ray and MR imaging for prostate I-125 post-implant dosimetry: phantom validation and preliminary patient work.

Post-implantation dosimetry is an important element of permanent prostate brachytherapy. This process relies on accurate localization of implanted seeds relative to the surrounding organs. Localization is commonly achieved using CT images, which provide suboptimal prostate delineation. On MR images, conversely, prostate visualization is excellent but seed localization is imprecise due to distortion and susceptibility artefacts. This paper presents a method based on fused MR and x-ray images acquired consecutively in a combined x-ray and MRI interventional suite. The method does not rely on any explicit registration step but on a combination of system calibration and tracking. A purpose-built phantom was imaged using MRI and x-rays, and the images were successfully registered. The same protocol was applied to three patients where combining soft tissue information from MRI with stereoscopic seed identification from x-ray imaging facilitated post-implant dosimetry. This technique has the potential to improve on dosimetry using either CT or MR alone.

Iron-deficiency anaemia and delay in the diagnosis of colorectal cancer.

AIMS: Iron-deficiency anaemia (IDA) is a recognized complication of colorectal cancer (CRC) especially with right-sided tumours, and failure to investigate the anaemia in older patients may lead to a delay in diagnosis. The aims of this study were to establish the proportion of patients with CRC shown to have an IDA for more than six months before diagnosis and to establish the proportion of patients with IDA who subsequently prove to have CRC. METHODS: All patients presenting with confirmed CRC in a health district (catchment population 280000) in the 4 years 1996-9 were identified from the pathology database after ethical approval. The criteria for IDA were haemoglobin (Hb) < 10.1 g/dl plus mean corpuscular volume < 78 fl and/or mean corpuscular Hb concentration < 32 g/dl. The haematology data-base serving the same population was searched for evidence of: 1. IDA at diagnosis of CRC; 2. IDA more than 6 months and more than one year before the diagnosis of CRC; 3. The number of haematology referrals per annum in women over 55 and men over 50 years of age meeting the criteria for IDA. RESULTS: Of 440 patients with colorectal cancer, 166 (38%) had IDA at diagnosis and of the latter 54 (12%) were known to have IDA for more than six months before diagnosis and 26 (6%) had IDA more than one year before diagnosis. IDA was more common in right sided tumours (65%) than in those arising in the left side of the colon and rectum (26%). The annual incidence of IDA in the sampled population was 1366 in the stated age group. CONCLUSION: The investigation of iron-deficiency anaemia in older patients is important but in order to detect 26 patients with colorectal cancer a year earlier, the investigation of approximately 5000 patients would be required--a detection rate of less than 1%.