Ingested foreign bodies (FBs) present a common clinical problem. As the incidence of FBs requiring operative removal varies from 1% to 14%, it was decided to perform this study and compare the data with those from the world literature, as well as to outline an algorithm for management, including indications for surgery. We reviewed all patients with FB ingestion from 1973 to 1993. There were 542 patients with 1203 ingestions, aged 15 to 82 years. Among them, 69. 9% (n = 379) were jail inmates at the time of ingestion, 22.9% (n = 124) had a history of psychosis, and 7.2% (n = 39) were alcoholics or denture-wearing elderly subjects. Most foreign bodies passed spontaneously (75.6%; n = 410). Endoscopic removal was possible in 19. 5% (n = 106) and was not associated with any morbidity. Only 4.8% (n = 26) required surgery. Of the latter, 30.8% (n = 8) had long gastric FBs with no tendency for distal passage and were removed via gastrotomy; 15.4% (n = 4) had thin, sharp FBs, causing perforation; and 53.8% (n = 14) had FBs impacted in the ileocecal region, which were removed via appendicostomy. Conservative approach to FB ingestion is justified, although early endoscopic removal from the stomach is recommended. In cases of failure, surgical removal for gastric FBs longer than 7.0 cm is wise. Thin, sharp FBs require a high index of suspicion because they carry a higher risk for perforation. The ileocecal region is the most common site of impaction. Removal of the FB via appendicostomy is the safest option and should not be delayed more than 48 hours.
The peripheral dose outside the applicators in electron beams was studied using a Varian 21 EX linear accelerator. To measure the peripheral dose profiles and point doses for the applicator, a solid water phantom was used with calibrated Kodak TL films. Peak dose spot was observed in the 4 MeV beam outside the applicator. The peripheral dose peak was very small in the 6 MeV beam and was ignorable at higher energies. Using the 10 x 10 cm(2) cutout and applicator, the dose peak for the 4 MeV beam was about 12 cm away from the field central beam axis (CAX) and the peripheral dose profiles did not change with depths measured at 0.2, 0.5 and 1 cm. The peripheral doses and profiles were further measured by varying the angle of obliquity, cutout and applicator size for the 4 MeV beam. The local peak dose was increased with about 3% per degree angle of obliquity, and was about 1% of the prescribed dose (angle of obliquity equals zero) at 1 cm depth in the phantom using the 10 x 10 cm(2) cutout and applicator. The peak dose position was also shifted 7 mm towards the CAX when the angle of obliquity was increased from 0 to 15 degrees.
Lung cancer treatment is one of the most challenging fields in radiotherapy. The aim of the present study was to investigate what role helical tomotherapy (HT), a novel approach to the delivery of highly conformal dose distributions using intensity-modulated radiation fan beams, can play in difficult cases with large target volumes typical for many of these patients. Tomotherapy plans were developed for 15 patients with stage III inoperable non-small-cell lung cancer. While not necessarily clinically indicated, elective nodal irradiation was included for all cases to create the most challenging scenarios with large target volumes. A 2 cm margin was used around the gross tumour volume (GTV) to generate primary planning target volume (PTV2) and 1 cm margin around elective nodes for secondary planning target volume (PTV1) resulting in PTV1 volumes larger than 1000 cm3 in 13 of the 15 patients. Tomotherapy plans were created using an inverse treatment planning system (TomoTherapy Inc.) based on superposition/convolution dose calculation for a fan beam thickness of 25 mm and a pitch factor between 0.3 and 0.8. For comparison, plans were created using an intensity-modulated radiation therapy (IMRT) approach planned on a commercial treatment planning system (TheraplanPlus, Nucletron). Tomotherapy delivery times for the large target volumes were estimated to be between 4 and 19 min. Using a prescribed dose of 60 Gy to PTV2 and 46 Gy to PTV1, the mean lung dose was 23.8+/-4.6 Gy. A 'dose quality factor' was introduced to correlate the plan outcome with patient specific parameters. A good correlation was found between the quality of the HT plans and the IMRT plans with HT being slightly better in most cases. The overlap between lung and PTV was found to be a good indicator of plan quality for HT. The mean lung dose was found to increase by approximately 0.9 Gy per percent overlap volume. Helical tomotherapy planning resulted in highly conformal dose distributions. It allowed easy achievement of two different dose levels in the target simultaneously. As the overlap between PTV and lung volume is a major predictor of mean lung dose, future work will be directed to control of margins. Work is underway to investigate the possibility of breath-hold techniques for tomotherapy delivery to facilitate this aim.
The dose distribution near a non-radioactive gold seed under a 6 MV photon beam was measured using radiographic film, water equivalent bolus and solid water slabs. This type of small seed is typically used as a marker in target positional verification using a portal imager for conformal prostate treatment such as intensity modulated radiation therapy. A stack of three films was placed on top of the seed located on a soft bolus. Solid water slabs were then placed on top of the film. The films were exposed using a small 1x1 cm2 field. Then, using a similar experimental set-up and exposure, another stack of three films was placed under the seed, which was then covered by the soft bolus and solid water slabs. The cross-plane axial beam profiles at different depths, depending on the thickness of the film package, were measured. From the group of beam profiles above and below the seed, the dose distribution along a selected vertical line within the profiles was easily plotted. Compared to the dose with no seed at the isocentre and 5 cm of solid water, there was about a 21% increase in dose at 0.35 mm above the seed. On the other hand, there was about a 22% decrease in dose at the same distance below the seed. The dosimetry of the calibrated film was verified with a MOSFET detector. The change in dose due to the seed by varying the incident beam angles was also measured for this note.
Helical tomotherapy (HT) is a novel treatment approach where the ring gantry irradiation geometry of a helical CT scanner is combined with an intensity-modulated megavoltage x-ray fan beam. An inverse treatment planning system (TomoTherapy Inc., Madison) was used to optimize the treatment plans for ten randomly selected prostate patients. Five different sets of margins (2, 5, 7.5 and 10 mm uniform 3D margins and a non-uniform margin of 5 to 10 mm) were employed for the prostate (GTV2) and seminal vesicles (GTV1). The dose distribution was evaluated in targets, rectum, bladder and femoral heads. HT plans are characterized by a rapid dose fall off around the target in all directions resulting in low doses (less than 30% of the dose at ICRU reference point) to the femurs in all cases. Up to a margin of 5 mm for target structures, it was always possible to satisfy the requirements for dose delivery set by RTOG protocol P-0126. Using a 'class solution', HT plans require minimal operator interaction and result in excellent sparing of normal structures in prostate radiotherapy.
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