Download Penentuan Dose Reference Level (DRL)

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FISIKA MEDIS
LAPORAN PENELITIAN HIBAH BERSAING
TAHUN ANGGARAN 2011
Penentuan Dose Reference Level (DRL) pada Prosedur Diagnosis Kepala
Menggunakan CT-scan sebagai Upaya Proteksi Radiasi
kepada Pasien secara Nasional
Drs. Johan Andoyo Effendi Noor, M.Sc., Ph.D.
dr. Indrastuti Normahayu, Sp.R.
Dibiayai oleh Direktorat Jenderal Pendidian Tinggi, Kementerian Pendidikan Nasional, melalui
DIPA Universitas Brawijaya REV.1 Nomor: 0636/023-04.2.16/15/2011 R,
tanggal 30 Maret 2011 dan berdasarkan surat dari DP2M Dikti Nomor: 121/D3/PL/2011
tanggal 7 Februari 2011
UNIVERSITAS BRAWIJAYA
NOPEMBER 2011
RINGKASAN
Salah satu aspek penting yang sangat diperlukan oleh seorang dokter, khususnya
dokter
spesialis penyakit dalam, dalam melakukan diagnosis suatu penyakit adalah keberadaan
dari citra organ-organ dalam tubuh yang sedang didiagnosis. Dengan bantuan citra bagian
dalam tubuh tersebut seorang dokter dapat melakukan diagnosis dengan lebih cermat,
sehingga terhindar dari kemungkinan salah diagnosis.
Sejarah pencitraan medis berawal dari ditemukannya sinar-x oleh Wilhelm Conrad
Röntgen pada tahun 1895. Citra sinar-x pertama atas organ tubuh manusia adalah foto
sinar-x tangan istrinya. Oleh sebab itu sampai saat ini foto-foto yang dibuat dengan
menggunakan modalitas sinar-x sering juga disebut dengan foto Röntgen. Kemudian
seiring dengan kemajuan di bidang komputasi, baik dalam bidang perangkat keras maupun
perankat lunaknya, teknik pencitraan dengan sinar-x telah mengalami kemajuan dengan
munculnya teknik Computerised Tomography, yang dikenal dengan CT-scan, yang pertama
kali diperkenalkan oleh Sir Godfrey Hounsfield (Hounsfield, 1973) pada tahun 70-an.
Sinar-x merupakan sepenggal spektrum gelombang elektromagnetik yang terletak di
ujung energi tinggi spektrum gelombang elektromagnetik di bawah dan bersingungan
dengan sinar gamma. Sinar-x mempunyai kemampuan yang sama dengan sinar gamma
dalam mengionkan benda-benda yang dilaluinya, sehingga keduanya juga dikenal sebagai
sinar pengion. Jika proses ionisasi ini terjadi pada jaringan lunak organ maupun cairan di
dalam tubuh manusia, maka bisa mengakibatkan terjadinya kerusakan sel, mutasi gen,
terbentuknya radikal bebas, dan sel-sel kanker.
Proteksi radiasi di dalam praktik pencitraan diagnostik dimaksudkan untuk menjamin
bahwa keuntungan penggunaan sumber radiasi lebih besar dari risikonya terhadap individu
yang terlibat. Optimasi proteksi dan keselamatan dilakukan dengan prinsip “As Low As
Reasonably Achievable.” Penggunaan berkas pengion sinar-x di dalam praktek pencitraan
diagnostik telah mengalami kemajuan yang sangat pesat, baik dari sisi teknik pengambilan
data, kualitas citra yang dihasilkan maupun jumlah tindakan. Dalam aplikasi radiasi, dosis
efektif merupakan parameter yang digunakan untuk menyatakan dan membandingkan
dosis radiasi yang diberikan kepada pasien.
The International Commission on Radiological Protection (ICRP) telah
mengeluarkan rekomendasi dosis efektif yang aman bagi manusia yang bisa digunakan
sebagai standar acuan. Sehingga Pemerintah Republik Indonesia sangat perlu mempunyai
standar nasionalnya yang mengacu kepada standar internasional ini.
Penelitian pada tahun pertama ini dilakukan dengan mengukur, menghitung dan
menganalisis dosis efektif pencitraan sinar-x pada mesin CT-scan di Instalasi Radiologi di
tiga rumah sakit besar di kota Malang, yaitu Rumah Sakit Saiful Anwar (RSSA), Rumah
Sakit Tentara Soepraoen (RST), dan Rumah Sakit Panti Nirmala (RSPN), yang diambil
sebagai rumah sakit peserta. Pengukuran dosis dilakukan pada pasien yang menjalani
eksaminasi kepala di rumah sakit peserta. Parameter-parameter CT yang diambil antara
lain: tegangan tabung (dalam kVp), arus tabung (dalam mA), waktu pemindaian (dalam
detik), panjang pindai (scan length
dalam cm), lebar kolimator (dalam mm), CTDIvol (dalam mGy), dan Dose Length Product
(DLP dalam mGy.cm). Dari data-data tersebut kemudian dihitung besar dosis efektif yang
diterima oleh pasien dengan menggunakan program komputer perhitungan CTDosimetry
versi 1.0.4 (dengan program Microsoft Excel) yang dibuat oleh ImpACTscan Inggris.
Hasil-hasil yang telah diperoleh memperlihatkan bahwa mesin CT scan di RSSA
(buatan General Electric Healthcare Inc. dengan tipe HiSpeed DX/i) memberikan dosis
efektif rata-rata sebesar 1,31 mSv untuk pasien laki-laki dan 1,19 mSv untuk pasien
prempuan, mesin di RST (buatan Siemens Healthcare System dengan tipe Somatom Spirit)
memberikan dosis efektif ratarata sebesar 1,38 mSv untuk pasien laki-laki dan 1,32 mSv
untuk pasien prempuan, dan mesin di RSPN (buatan Siemens Healthcare System dengan
tipe Emotion6) memberikan dosis efektif rata-rata sebesar 2,06 mSv untuk pasien laki-laki
dan 1,93 mSv untuk pasien prempuan. Tampak dari hasil-hasil tersebut mesin Siemens
Emotion6 memberikan dosis paling tinggi dan mesin CT GE HiSpeed DX/i memberikan
dosis efektif paling kecil. Secara umum, mesin yang menerapkan pencatuan arus adaptif
(GE) memberikan dosis yang lebih kecil dibandingkan dengan mesin yang arusnya dicatu
secara tetap/konstan (Siemens).
SUMMARY
One important tool required by a medical doctor, especially an internist, in
conducting a clinical diagnose is internal images of the body under investigation. The
images will help the doctor in diagnosing his/her patients more accurately to avoid any
misdiagnose.
The history of medical imaging started after the discovery of x-ray by Wilhelm
Conrad Röntgen in 1895. The first x-ray image of human body ever made was the image of
the hand of Mrs. Röntgen. The photography that utilizes x-ray beam to produce images is
called a Röntgen photography. In the wake of and advances in computing technology, both
in hardware and software aspects, the x-ray imaging technology follows by the invention of
the Computerized Tomography, also known as CT-scan, by Sir Godfrey Hounsfield
(Hounsfield, 1973) in early 70‘s.
X-rays lie in the high energy end of the electromagnetic spectrum just below and
overlap with the gamma-rays. Therefore, x-ray has the similar capability to gamma-ray in
ionizing matters they are passing through. This capability makes them be called ionizingrays. If the ionization occurs in soft tissues of the organs or to the electrolites in the body,
cell damage, gen mutation, free radical formation, dan cancer cells production may result in.
Radiation protection in diagnostic imaging practices is aimed to ensure that the
benefits of the use of ionizing radiation exceed the risk resulted in to the individuals
involved. Protection and safety optimization is conducted using a principle of ALARA (As
Low As Reasonably Achievable). The employment of ionizing x-ray beam in the diagnostic
imaging practices has been advancing very rapidly in the aspects of image acquisition
technique, image quality, and the number of procedures carried out. In the application of
radiation, the effective dose is a parameter used to express and compare the radiation
doses received by patients.
The International Commission on Radiological Protection (ICRP) has published its
recommendation on the effective dose safe to humans that can be used as the reference
standard. In the sake of public protection, the Government of the Republic of Indonesia
must establish a national standard by adopting the ICRP standards.
The research in the first year was carried out by measuring, calculating, and
analyzing the effective doses from examinations using CT-scanners at the Department of
Radiology of three main hospitals in Malang: Rumah Sakit Saiful Anwar (RSSA), Rumah
Sakit Tentara Soepraoen (RST), and Rumah Sakit Panti Nirmala (RSPN), that were taken
as the participant hospitals. The dose estimations was conducted from patients sent to the
departments for head examinations. The CT parameters taken were: tube voltage (in kVp),
tube current (in mA), scan time (in second), scan length (in cm), collimator width (in mm),
CTDIvol (in mGy), and the Dose Length Product (in mGy.cm). The effective dose of each
patient was estimated and calculated from the acquired data using a computer
programming CTDosimetry version 1.0.4 (in Microsoft Excel) written and distributed by the
ImpACTscan team of the UK.
The results reveal that the CT-scanner in RSSA (General Electric Healthcare Inc.
type HiSpeed DX/i) gave an average effective dose of 1.31 mSv for male patients and 1.19
mSv for female patients, the CT-scanner in RST (Siemens Healthcare System type
Somatom Spirit) exposed the patients an average of 1.38 mSv for male patients and 1.32
mSv for female patients, and the CT-scanner in RSPN (Siemens Healthcare System type
Somatom Emotion6) delivered an average dose of 2.06 mSv for male patients and 1.93
mSv for female patients. The calculations show that the Siemens Emotion6 delivered the
highest dose and the CT GE HiSpeed DX/i delivered the lowest. This reveals that the
system that employs an adaptive current supply (the GE) produces a lower radiation dose
compared to the machines that use a fixed current technique (the Siemens).
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