Stratified sampling procedure was employed to collect a total of 40 samples; 2 from each stratum, measuring an approximate dimension of 3.25 km(2) of the actual sample site. Appropriate volumes were then evaporated and transferred into clean stainless steel planchets (ISO 9696 and ISO 9697). An eight channel gas-flow proportional counting system connected to a microprocessor loaded with a spreadsheet programme (Quarttro-Pro) and graphic programme (Multiplan) initially calibrated for efficiency was employed to count the background and the prepared samples. A mean efficiency of 33.44 and 41.24 % for the respective alpha and beta sources was obtained. A low background activity was also observed with a mean of 0.165 Bq for alpha and 1.119 Bq for beta. The gross alpha and beta activity concentrations in the water were found to range from 80 +/- 0.05 to 2300 +/- 0.41 Bq m(-3) and 120 +/- 0.08 to 4970 +/- 0.78 Bq m(-3), respectively. This clearly indicate areas of elevated alpha and beta activity concentrations of 37.5 and 47.5 %, respectively when compared with the International Commission for Radiological Protection (1991) maximum acceptable values of 500 Bq m(-3) for alpha and 1000 Bq m(-3) for beta.
The objective of this study was to determine the gross alpha and gross beta activity concentrations from the different soil types found in the Kinta District, Perak, Malaysia. A total of 128 soil samples were collected and their dose rates were measured 1 m above the ground. Gross alpha and gross beta activity measurements were carried out using gas flow proportional counter, Tennelec Series 5 LB5500 Automatic Low Background Counting System. The alpha activity concentration ranged from 15 to 9634 Bq kg(-1) with a mean value of 1558±121 Bq kg(-1). The beta activity concentration ranged from 142 to 6173 Bq kg(-1) with a mean value of 1112±32 Bq kg(-1). High alpha and beta activity concentrations are from the same soil type. The results of the analysis show a strong correlation between the gross alpha activity concentration and dose rate (R = 0.92). The data obtained can be used as a database for each soil type.
Concentrations of uranium and thorium in seawater, sediment and some marine species taken from along the coastal areas of Malaysia were determined spectrophotometrically. The uranium and thorium concentrations in seawater were found to vary ranging from 1.80 to 4.1 and 0.14 to 0.88 microg/L, respectively. The concentration of uranium in sediment samples was reported to range from 3.00 to 6.60 microg/g while those of thorium were slightly lower ranging from 0.01 to 0.68 microg/g. The uptake of uranium and thorium in marine species was found to be rather low. Similar variations in total alpha activities in samples were also observed with the total alpha activities relatively lower than the beta activities in most samples.
Pterygium is a common external eye problem. It is more frequently seen in tropical areas regions where exposure to ultraviolet sunlight is high. Clinically, a pterygium is a wing shaped fibrovascular growth arising from the bulbar conjunctiva onto the superficial cornea. Complications of pterygium include decreased in visual acuity, dryness, foreign body sensation and persistent redness. Surgical management is the mainstay of treatment for this condition. Numerous surgical techniques have been described in the treatment of pterygium. They include the bare sclera technique, simple direct conjunctival closure, rotational conjunctival graft and conjunctival autograft. Additional treatment to some of these techniques may include the use of beta particle therapy and antimetabolite therapy. Despite the wide range of surgical procedures described for its treatment, the main concern from these procedures has been the recurrence, which could be as high as 30% to 70%. Recurrent pterygium is often accompanied by increased conjunctival inflammation and accelerated corneal involvement. Repeated surgical procedures often only worsen the situation, as loss of conjunctival tissue and scarring can result in obliteration of the fornices and mechanical restriction of extraocular movements, with clinically significant diplopia. In Hospital Tengku Ampuan Afzan, pterygium excision is the most common surgical procedure after cataract extraction. We reviewed patients who had undergone pterygium surgery in HTAA in order to determine the most effective surgical method that could minimize recurrence. PURPOSE: To compare success rates of various excision techniques performed for primary and recurrent pterygium in Hospital Tengku Ampuan Afzan, Kuantan, Pahang.
METHODS: The outcome of 47 cases of pterygia (44 primary and 3 recurrent) excised with various techniques between January 2004 to September 2004 was retrospectively reviewed. Six clinical specialists and four trainees performed the surgical procedures. Outcome was evaluated in terms of recurrence of pterygia onto the cornea. RESULTS: The mean follow up was 3.04 months (range, 1-7 months). All pterygia were morphologically graded as intermediate or fleshy type except one. Four types of pterygium excision techniques were performed. Twenty-four cases had bare sclera, seventeen cases had conjunctival autograft transplantation, six cases had direct conjunctival closure and one had amniotic membrane transplantation done. Recurrence of pterygia occurred in thirteen eyes. Twelve cases from primary pterygia group and one case from recurrent group recurred. Recurrence rate was noted to be higher in direct conjunctival closure (4 out of 6 cases) and lowest in conjunctival autograft transplantation (2 out of 17 cases). Recurrence rate for bare sclera technique was noted to rank second in this study (6 out of 24 cases). In five cases of recurrence, subconjunctival tissue invasions were more than 1 mm but further surgical interventions were not needed at the time of this review was done. CONCLUSIONS: Conjunctival autografting was found to have less recurrent rate when compared with other techniques. The bare sclera technique was quoted to be associated with higher recurrence rate in other literatures. Interestingly in our series, recurrence rate for direct conjunctival closure technique was higher when compared to the former technique. This may be related to inadequate excision of pterygia tissue, which led to direct apposition of abnormal tissue to the cornea in the direct conjunctival closure technique. Even though the bare sclera technique is associated with a higher recurrence rate, it is still the preferred excision technique. This could be because it is less time consuming and technically easier to perform. Based on this study, conjunctival autografting should be the surgical procedure of choice for pteryigum in order to minimise the risk of recurrence.